PHIL 201-01




Philosophy Course Index



Course notes are at the bottom of the page, along with paper assignments, and tips for writing a philosophy paper.







                                                                                                            Course ID # 000179                                                          T H 12:30-1:50 PM

Winona State U.                       Spring 2018                         Minne 104


Instructor: Ed Slowik/325 Minne Hall/Office phone: 457-5663                                                                                                          


Office Hours:  T H 2:00-3:00 PM, and by appointment. I'm usually free in the late afternoon, but the best time to talk to me is just before or after class.



Required: Thales to Sextus, G. Thomson (Waveland).

Introductory Readings in Ancient Greek and Roman Philosophy, Reeve and Miller (Hackett).


Course Objectives:

This course covers Ancient Greek philosophy, from the Pre-Socratics through Plato, Aristotle, and a few later thinkers, with special attention placed on their metaphysics and epistemology.


Course Requirements:

One in-class midterm (25%), in-class final (25%), and two papers (25% each). The papers are 7-10 pages double-spaced, on a topic provided by the instructor. The midterm and final are of the short answer, short essay type. Dates for the midterm and final are as follows:


Midterm: Thursday, March 1; Final exam: Monday, April 30, 10:30 AM-12:30 PM.


The due dates for the papers are listed in the class schedule below.


Web Page:

Information on the course will be posted on my class web page. The information will pertain to: syllabus, class notes, description of the term paper assignment, and tips for writing a philosophy paper. The address is:



Schedule (tentative):

The primary readings will be fairly extensive, and the material difficult, but the lectures and class notes should help greatly. The readings listed below are from the Allen book, but readings from the other book will be assigned in class. I will announce the specific reading assignments for each upcoming week (and day) in class. I may give several (free) hand-outs in class: but don’t lose them, since I’ll charge you for replacements.


Week 1. Introduction, start Presocratics: Reeve & Miiler (R&M), pp. 1-44; Thomson, Introduction & Part I (Jan. 9, 11)


Week 2. Presocratics continued (Jan. 16, 18)


Week 3. Plato: R&M, pp. 44-245; Thomson, Part II (Jan. 23, 25)


Week 4. Plato continued (Jan. 30, Feb. 1), Paper#1 assigned, H, Feb. 1


Week 5. Plato continued (Feb. 6, 8)


Week 6. Plato continued (Feb. 13, 15), No Class, T, Feb. 13 (Assessment Day)


Week 7. Plato continued (Feb. 20, 22), Paper#1 due, H, Feb. 22


Week 8. Plato continued, Midterm (Feb. 27, March 1), Midterm, H, March 1


Week 9. Aristotle: R&M, pp. 245-305; Thomson, Part III (March 13, 15)


Week 10. Aristotle continued (March 20, 22)


Week 11. Aristotle continued (March 27, 29), Paper#2 assigned, H, March 29


Week 12. Aristotle continued (April 3, 5)


Week 13. Hellenistic and Roman philosophy, and Neoplatonism: R&M, pp. 352-459; Thomson, Part IV (April 10, 12)


Week 14. Hellenistic and Roman philosophy, and Neoplatonism continued (April 17, 19), Paper#2 due, H, April 19


Week 15. Hellenistic and Roman philosophy, and Neoplatonism continued (April 24, 26)


Final Exam: Monday, April 30, 10:30 AM-12:30 PM (same classroom)


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Take-Home Essay Assignments


Classical Philosophy 201  WSU, Spring 2018


Take-Home Essay Assignment #1   (7-10 pages, due Thursday, February 22)


Do four of the following questions:


1) Explain the theories of the Milesian philosophers, Thales, Anaximander, and Anaximenes, on the nature of the “one” that underlies change.


2) Explain the world view of the Pythagoreans, especially on mathematics and the soul.


3) Explain, compare and contrast, the views of Parmenides and Heraclitus.


4) Explain Zeno’s arguments against motion. What is their purpose? (You might want to use my notes from the “Space and Time” course on my web page).


5) Explain the views of the Pluralists, especially the Atomists.


6) What is Socrates defense in the Apology, and the reasons why he won’t escape Athens in the Crito?


7) Explain the theory that learning is recollection from the Meno.


8) Explain the theory of the Forms as presented in the Phaedo.














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Tips for Writing a Philosophy Paper

The main point of most undergraduate philosophy papers is to present positions backed by reasons and arguments. Even if you are simply giving a philosopher's views on an issue, you need to be able to present the arguments he or she relied on. Indeed, mere opinions, whether your own or those of a well-known philosopher, are worthy of a serious hearing only when backed by reasons.

Thus a philosophy paper is not just a series of opinions spouted by its author, nor a straightforward reporting of events, nor a “book report” or capsule summary of some famous person's views. It involves giving, and weighing, arguments. If this seems intimidating, you should know that there are some easily understood tips and techniques for writing philosophy papers. They do not eliminate the work involved in writing the paper—nothing will do that for you—but they can help you systematically approach your topic. And with enough practice, you will find yourself applying them almost automatically. (Incidentally, the plain fact is that most people who are good at this kind of thing were not born that way, but got that way by practice.)

Getting started.

A common mistake made by undergraduates is choosing a very large topic, one that calls for much more discussion than can be provided in a paper of six, eight, or even twelve pages. In general, it is better to say a lot about a narrow topic, than to say a little about each aspect of a broad topic. (Thus, for example, it is more productive to discuss in detail a single argument for the existence of God, like the Argument from Design, than to run quickly but superficially over the many different arguments for the existence of God.)

Once you have found a suitable topic, formulate to yourself a claim about it that you wish to defend. For example, if your topic is the Argument from Design, then your claim might be that this argument does not succeed in establishing God's existence. Or, if your topic is the distinction between primary and secondary qualities, your claim might be that Locke was right about this distinction, and that Berkeley, who disagreed with Locke, was wrong.

Once you have formulated your claim, try to think of arguments that support it, and also arguments that seem to undercut it. This sounds hard, but recall that, if your topic was discussed in your philosophy class in the first place, then probably there was also some discussion of arguments for it or against it. Moreover, it is perfectly acceptable to use arguments drawn from other philosophers. You must, however, show that you understand these arguments and are not just “parroting” someone, and you must acknowledge your source for the argument. Failure to credit sources properly is plagiarism, and will result in a failing grade for the course.

One of the most impressive things you can do in a paper, besides giving good arguments in support of your claim, is to anticipate objections (the “arguments that seem to undercut it,” mentioned above), and to show that they do not succeed. Moreover, it is a grave error to ignore or overlook undercutting arguments that have actually been presented in your class or in assigned readings. If you disagree with them, you should say why; but to simply omit them is to ask for a bad grade.

As for evaluating such supporting and undercutting arguments, that is a skill that cannot be imparted here in a paragraph or two. The way to learn it is to see how others do it (particularly in class, but also in philosophy books and articles), and to try to do it yourself. Some of the appropriate techniques are: (1) to assess whether the argument uses key terms properly; (2) to see whether the argument rests on one or more premises that are questionable; and (3) to see whether the argument, if accepted, leads to consequences which do not square with known facts or credible theories.

Showing understanding.

How do you show that you are not just “parroting” someone? The main way is to put things in your own words. It is all too easy to think that you understand something just because you can regurgitate some buzzwords. Real understanding typically goes hand in hand with formulating things for yourself, in your own words. Several rules of thumb are helpful here. One is to avoid jargon where possible; if you must use it, be sure to give a definition. Jargon, for our purposes, is wording that rarely or never arises in ordinary conversation, or that is being used in some non-ordinary way. Another rule of thumb is to write as if you were explaining something to someone who is intelligent, but is not a specialist in the subject, e.g. a favorite grandparent. Do not, in particular, write with jargon in the hope that your professor will like it better or will understand it better (even if you don't).

Another key technique for achieving, and showing, understanding is to come up with your own examples to illustrate key points. Many philosophical positions, though highly abstract and general, readily lend themselves to concrete illustrations. For example, Hume's ethical claim that no `ought' can be derived from an `is', comes alive when fleshed out as the claim that nowhere among the facts about what happens when I cut off Joe's head is there anything that tells me whether I ought not to cut off his head. (Hume himself knew this, of course; indeed, he gives even more hair-raising examples.)

Note, however, that examples illustrate and hence clarify, but that they do not take the place of arguments. Thus you still need to be able to explain the underlying principles in words—you still need to be able to explain why the example is an example.

Finally, do not leave things unclear or make sloppy statements and then say to the professor, “Aw, c'mon, you know what I meant!” Your professor can't read your mind, and will probably assume from previous experience with other students that you yourself do not know what you mean. The safest course is, naturally enough, to say just what you mean.

Writing with clarity.

It is crucial, not just to have something to say, but to say it effectively. The most effective presentation usually follows the old saying: “Tell 'em what you're gonna tell 'em; tell 'em; then tell 'em what you told 'em.” That is, begin with an introductory paragraph in which you say what you take yourself to be doing in the paper; then, after you have presented your case, close with a conclusion which says what you have done. If you do not say up front, in the introduction, what you will be doing in the body of the paper, your reader will probably conclude that you do not know what you are up to in your paper. (This is an all-too-frequent situation, especially for students who put off papers until the last minute.)

This does not mean that you must write your introduction first. On the contrary, it is typically better to launch into writing the body of the paper first, since the writing process often brings insights and changes of opinion that you didn't expect. So it is prudent to wait until you are happy with the body of the paper, and then go back and write an introduction that spells out in a nutshell what you are doing in the body. The same goes for the conclusion, of course.

You may be tempted to avoid “tipping your hand” at the beginning of your paper, so that your reader is led suspensefully and dramatically to the eventual unveiling of your key points. Avoid this temptation. It is much more difficult to pull off than you might imagine, and your reader will appreciate much more the up-front approach, pedestrian as it may seem.

A final point about introductions and conclusions is that they should not include grandiloquent phrases. Avoid saying things like, “Throughout history, people have struggled with the question of what makes an action good,” or “Aristotle was the greatest philosopher who ever lived, and his influence is still being felt today.” Your reader, far from being impressed, will be thinking, “Cut to the chase.” Remember, you're not actually writing for your grandparent; you should merely put things as clearly and simply as if you were.

Structure and grammar.

Proper structure at all levels of your paper will help immensely in getting your points across. Choose words in a way that avoids ambiguity. For example, if you use the word “it”, be sure that it is clear to which “it” you are referring. It can help to have a friend read your paper, looking for ambiguities that you might have overlooked. Likewise, you should avoid run-on sentences or incomplete sentences, which can be very confusing to read.

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Course Notes


Notes for Classical Philosophy (PHIL 201)

(Partially based on notes by Geoff Gorham, Macalester College, and Thompson’s Thales to Sextus.)


Background to Presocratic Philosophy.


The dominant viewpoint, prior to the Presocratics, was essentially mythical, supernatural, and anthropocentric (as opposed to scientific and objective). The principles and causes of the origin of the universe are personal: desires, purposes, emotions, sexual reproduction and so on (as in Hesiod). For the Milesians philosophers the distinction between philosophy and science is unclear, but what is important is that their approach to knowledge is naturalistic (lawlike) and rational, as opposed to mythical or supernatural.


The Milesians



We know of Thales (624-545) only from second-hand reports, such as Aristotle and Diogenes Laertis. He wrote nothing, but he was involved in science and mathematics, as well as philosophy. Water is the origin and material basis of all things. So here is a first form of matter theory: the attempt to explain the observable differences among things in terms of some underlying universal material principles. Aristotle says that Thales "probably derived his opinion from observing that the nutriment of all things is moist, and that even actual heat is generated there from, and that animal life is sustained by water." Clearly, water is changeable in a way that other things (such as earth) don’t seem to be.



Anaximander (610-545) pictured the structure of the universe as composed of four basic elements, earth, air, fire, water, but there was a deeper thing, the Unbounded, that lay underneath and comprised the four elements. 

The structure of the universe is governed by interaction of opposite principles embodied by material elements: (earth = dry) is opposed to (water = wet), and (fire = hot) is opposed to (air = cold). Change is constant, and so the action of the opposites is a sort of battle, which proceeds by a kind of eternal justice: e.g., summer to winter and back, wet to dry and back, etc. It is not clear whether this principle of justice transcends the world, but it seems necessary and non-personal. We have perhaps something of the notion of a “law” of nature here: there is a regular and necessary law for all natural changes.  All of these changes are some kind of constant modification of the Unbounded, also called Apeiron. One of the four elements could not be basic, since everything would be that element now: how could there ever be wet (water) from dry (earth), for example? The Apeiron is not bounded (though perhaps not infinite); it is eternal (since why and how could it have come to be?); and it has no parts (for what could distinguish one part from another?). He seems to think that the elements arise from the Apeiron by a kind of separation. It is eternal and divine, and “steers all things”, though, as in Thales, it is unclear how this works. Both thinkers seem to feel the need to endow the natural world with an agent of change – otherwise it would be dead. In biology, he held that all things came from the sea or moist earth by a kind of evolution.



A Student and younger contemporary of Anaximander, Anaximenes (580-502) rejected the abstract notion of an underlying substance, Apeiron (perhaps on the scientific grounds that it is unobservable or unfalsifiable). It is Air, not water, that is the basic thing that underlies the universe. It undergoes differences in density, and this explains how the four elements arise: condensation of air changes it to water and then earth; rarefaction changes air to fire. Thus, he explains how the fundamental material element can come to be in different ways. Air was also related by Anaximenes to the source of movement of the universe, it is “the breath of life”.


Pythagoras and the Pythagoreans


Pythagoras (570-497) was born in Samos, near Miletus but settled in Southern Italy (Croton). He wrote nothing and it is rather hard to distinguish his views from those of his many followers. His movement can be considered a religious/political cult, with secret doctrines, ceremonies, diets, etc. At various times they held significant political power, even ruling small kingdoms. He was very influential on Parmenides and Plato. He also certainly influenced some Renaissance astronomers such as Copernicus and Kepler (in part for his rejection of geocentrism but mainly for his mathematical orientation).


(1) World is Mathematical

They thought that, in some sense, the world is mathematical, but it is unclear what they may have meant. They may have simply believed that it is possible to offer a mathematical description of the world, or, they may have held the much more radical view that the world is itself made of (constructed from) numbers. Question: how did the Pythagoreans interest in music encourage such a view? Answer: the ratios between natural numbers that determine the octaves and musical harmonies are universal (independent of the instrument played). Certain mathematical proportions are also common to branches, leaves, and river systems. Objection: It is one thing to say that the physical word obeys certain numerical ratios, and something altogether to say (as Pythagorean may have claimed) that the world itself is numbers. That is, one can distinguish between the form or structure of something (which may be mathematical) and its matter or content (which is not a number). Most importantly, numbers do not seem to occupy space, so how can they spatial bodies be constructed out of them? Answer: the Pythagorean position might derive from their peculiar way of representing numbers as collections of points or units. They represented numbers by arrangements of dots or pebbles such as ten (tetracytus), which have a position in space, and so they may have thought that bodies were made up of numbers (units) in something like the same way. Odd and even numbers were associated with different properties in the world: even with the unlimited, female, many, dark, bad, etc.; odd with limited, male, one, light, good, etc. They were the first to develop abstract mathematics (along with theorems and proofs, etc.).


(2) The Soul

They were perhaps the first Greeks to develop the notion that the soul (psyche) was separate from the body and immortal. In earlier views, the psyche is the life-force which gives motion and life to the body, but is not strictly a separate thing. They seemed to regard our current embodied state as a bad thing, as a kind of prison which we would naturally hope to escape (and they also believed in reincarnation). There is nothing like these views in the Milesians. The Pythagoreans urged that we engage in mathematical and philosophical inquiry as a means of purifying our soul. Why would doing math and science purify our soul? Answer: The world, being mathematical, is inherently orderly. We can achieve a certain order in our own soul by studying math. The basic aim is a literal harmony with the world.




Heraclitus (540-475) was born a noble of the city of Ephesus, which is near Miletus. He was probably familiar with Pythagoras’ teachings and was certainly strongly influenced by the Milesian cosmologists. Perhaps owing to his high birth, he was contemptuous of democracy and of the broad masses of humanity generally. He wrote in a very obscure style and was a sort of mystic. “Logos” (literally, “word”, but maybe “plan”) is the first principle of things, and seems to stand for the unity of a process that governs the world by means of opposites (opposites that are in conflict, but in equilibrium at each moment: peace/conflict, one/many, etc.). Fire is associated with Logos, and seems to be the basic element of things. One of the most important aspects of Heraclitus’ worldview is that everything is in constant flux, i.e., everything constantly changes: his famous example is a river, since a river is never the same river at each moment (since the water in it keeps flowing, and so is never composed of the same water).


The Eleatics



Parmenides (510-445) was born in the city of Elea in Southern Italy. He was influenced by, but rejected the system of, Heraclitus. He may have been a Pythagorean while young, probably met Socrates and certainly influenced Plato. Despite his poetic style, Parmenides is the first philosopher to offer something like what we would recognize as arguments, where certain reasons are given which are intended to lead to or establish a conclusion. His approach resembles that of a modern philosopher, since it emphasizes precision, conceptual analysis, logic.

The central concept of Parmenides thought is that a world of plurality (i.e., many different things) and change is an illusion: there is only One Being, which is unchanging, uncreated, indestructible, timeless, and is shaped as a sphere. He believed in a world where the reality of things is different than how it appears to us (i.e., things appear to change, but they really don’t). Also, he seems to hold that all things happen by necessity, such that there is no chance or contingency in the world. Parmenides was also concerned with, what we would call today, “negative facts” or “non-existence”, such as “the present King of France” (this is a negative fact or a non-existent thing because there is no such person). The debate on this is hard to discern in Parmenides, but he seems to hold that we can only think about existing things. Take, for example, “WSU”: we cannot think “not WSU”, since that would be a contradiction. Why: because, if WSU does not exist, how can we think about it? This, needless to say, is problematic, because I can think of hypothetical or fictional beings, such as the “present King of France”. Parmenides seems to have based his philosophical view that change is impossible on his rejection of non-existence: on his reasoning, change requires either that something comes from nothing, or that something comes to not exist; but, this is impossible since the non-existent cannot be conceived. Hence, there can be no change.  



For more detailed analysis of his paradoxes, see the Zeno section (chapter 3) in my “notes on space” from my “Space and Time” class on the class web page.


Zeno (490-430) was a student of Parmenides who developed arguments that were intended to support Parmenides view that there is no plurality or motion/change. His basic strategy was the reductio ad absurdum argument: i.e., he tries to show that if one assumes plurality or motion, certain absurd consequences result. We will only cover some of these paradoxes.


Arguments Against Motion:


(1) The Stadium

This argument tries to show that any motion over a finite length of space is impossible. To move over a finite length, one must first cover half the distance, and then half of the remaining distance, and then half of the remaining distance again, etc. But, since the distance of this finite length can be continuously cut in half without running out of space to cut in half (since the division of any finite length is infinite), it is therefore impossible to traverse any finite distance.


(2) Achilles and the Tortoise

The slowest cannot be caught by the fastest, since during whatever period of time is required to catch the slowest, the slowest will have at least gone some distance. In the time it takes for Achilles to reach the tortoise’s position, the tortoise will move to another position, and so Achilles will always get closer, but never reach, the tortoise. Hence motion implies that the faster cannot overtake the slower. This is a variation of the Stadium argument, but with a moving endpoint for the finite distance traversed.


Aristotle's first response to these paradoxes: one can’t cover an infinitely big space, but one can, in the case of a finite distance, traverse an infinity of parts since there are an equal number of infinite temporal parts of the finite temporal period in which it takes to traverse that finite distance. Aristotle states that this response is weak, however, due to the fact that Zeno's paradox can also be applied to temporal units. Thus, appealing to time does not solve the problem because time also runs afoul of the paradox. Aristotle's second response is much better: the infinity of the finite spatial distance is only potential, and not actual, thus one can cover a potential infinity without problem (but not an actual infinity). That is, since the division of the finite distance is only a potential division, one does not need to make actual divisions of that finite length, which is a task that would never end. This response seems to imply that physical space is not the same as mathematical/geometric space, since the infinite geometric divisions of the space are not real (actual), but only potential.


(3) The Arrow

At any instant during the flight of an arrow, the arrow is either moving or at rest. But it can’t move in an instant (since it occupies only its own space at an instant). So it must be at rest. But if it is at rest at each instant, then it is never moving. So, how can an arrow that is at rest at every instant during its motion ever bring about real motion? Aristotle’s response is that a finite temporal period is not composed of durationless instants (just as a finite extended line is not composed of non-extended points). Points in time (like points of a line) are only potential, and not actual (since they constitute boundaries of extended durations/lengths). Hence, the paradox is resolved since the mere potentiality of instants of time does not necessitate that the arrow actually be at rest (or in motion) at an instant.  


(4)Arguments Against Plurality

If there are many things, there must be a definite number of things (such that they are no more or no less in number); but, they would then be both infinitely small (such that they have no size at all), as well as infinitely large. First, if they are definite in number, they would have to be infinitely small, that is, they would need to be indivisible units with no size. If they had size, then they would be infinite in number, through division, whereas we have assumed that are definite in number. But, this is impossible: they must have size or they would cease to exist. But, as just explained, if they have size, then they would then be infinitely large, since they would be infinitely divisible, and so you could aggregate these divisions of finitely-sized things into something infinitely large in size.


The Pluralists


Empedocles (492-432) and Anaxagoras (500-428) are the main members of this school (although the atomists are often included in this category as well). Both of these philosophers put forward views which are reminiscent of the naturalistic conception of the world that one finds in the Milesians, although there is much uncertainty about various aspects of their philosophy, which often seem more supernatural or mythical. Empedocles concept of the natural world centered on the four elements (called “roots”), earth, air, fire, and water, which he regards as the basic, indestructabe things that comprise the universe. For Anaxagoras, the basic stuff that comprises the world, which he calls “seeds”, is unclear, but it may simply be all of the different types of material things that we encounter in the world (e.g., bones, flesh, flowers, etc.). Like Parmenides, both accept that their respective basic stuffs cannot go out of existence, but both reject Parmenides’ argument that there can be no change. For Empedocles, change occurs when the basic elements (which are indestructable) recombine to form different things (much like the atomists, see below). For Anaxagoras, who thinks that “in everything there is a portion of everything” (i.e., that any object is a mixture of all the basic types of stuff, see above), change apparently occurs when the proportion of one type of stuff (say, bone) becomes the dominant ingredient in an object. That is, since any object contains all of the basic stuffs, if the proportion of one of those stuffs becomes the predominant stuff in that object, then the change of that object (say, from flesh to bone) is explained. The atomists accept the argument that change is possible, too, although they posit that atoms (and the void) are the basic stuff of the world. Unlike the atomists, as will also be explained below, there are processes or forces in the world that are responsible for change: For Empedocles, it is Love/Strife, or attraction/repulsion; for Anaxagoras, it is Mind (Nous). These processes can be interpreted as somewhat like laws of nature, which drive the changes in the world by operating on the basic elements or stuff of the world, but there is also a decidedly mind-like (or soul-like) aspect to this philosophy, such that the process appears to be similar (in an anthropomorphic way) to a person’s desires or will (e.g., a mind drives these changes).


The Atomists


Leucippus and Democritus

Both were fifth-century BC philosophers who accepted the existence of the void, that is, non-being or the non-existent, which might be empty space. Thus, they reject the view of Parmenides, who thought that non-being, or the non-existent, was a contradiction. They argued that “non-Being exists as much as Being” (but there is no void in atoms). The atomists posited the existence of atoms, of course, which are very small, unobservable, indestructible material particles of various sizes that move about randomly in the void, and ultimately join together to form larger material aggregates (i.e., the material objects that we experience, and that would include humans and other living things). And, the atomists seem to have accepted Zeno’s argument that an infinitely divisible material thing leads to a paradox, hence, their atoms are not divisible. For the atomists, the atoms and the void constitute the universe; so, the four basic elements (earth, air, fire, water) are composed of atoms and void, just like everything else. Since the universe consists of atoms that combine to form all of the things that we experience in the universe, they are the unchanging “one” that underlies all of the changes in the world. The atomists also seem to have claimed that all events happen in the universe by reason and necessity. The atoms are geometrical in nature, changeless, and are not mind-like: that is, certain properties of things, like colors and tastes, are not in atoms, but are caused in us by atoms through their combined interactions with our sensory organs. Aristotle claims that shape, arrangment, and position are central to the atomist’s picture as regards how things come about from atoms. The atomists apparently did not accept that atoms have an internal source of motion; rather, the atoms have always been moving (since the universe is infinitely old), and they collide with each other and thereby change their states of motion (and they also move in large circling pools, or vortices, to form different worlds, or systems of planets, in the one universe). Most philosophers of that time period thought that the natural state of material objects was a state of rest, but the Atomists did not accept this view. In this way, they seemed to foreshadow the concept of inertia (that objects are indifferent to rest or uniform motion). In short, the Atomists were a forerunner to modern science, e.g., the orientation of their thinking about nature is quite mechanistic, as is their idea that certain sensory properties (color, tastes, etc.) are only appearances caused by a quite different type of entity (atoms) that interact with our sensory organs. Whiile Leucippus came first, most of the views described above come from Democritus (460-360), Leucippus’ student.


The Sophists


The Sophists were a group of 5th century BC intellectuals and teachers who presumably taught virtue and ethics, but are usually associated with teaching rhetoric (the art of persuasion) for those wealthy Athenians who wanted to advance in the public life. Plato and Aristotle depict them in a negative way, as relativists (i.e., the view that all truth is relative to individuals or cultures, and thus there are no objective truths which are the same for all), and, more damagingly, as only concerned with winning arguments, regardless of the truth. This interpretation of the Sophists, as intellectual charlatans who did not care for the truth but only for persuading people, is probably unfair, but little has survived of their writtings, and thus it is difficult to judge their goals or accomplishments. Protagoras (490-420), one of the most famous of the Sophists, famously wrote that “man is the measure of all things”, but it is unclear how to interpret this claim: it could be an expression of a relativism about truth (such that truth is entirely relative to each person’s beliefs and judgments), or merely an observation that different cultures or individuals have different customs, religions, social practices, etc. Overall, the sophists were skeptical of religions (many were atheists or agnostics), and they were aware of the differences among cultures. Accordingly, this skepticism of the gods and their understanding of the variability of social arrangments may have been interpreted by some as potentially dangerous to the established Athenian social order. One earlier philosopher (6th century BC) who should be mentioned in this context is Xenophanes (570-475), who argued that the nature of the gods is relative to culture, and anthropomprhic (based on human qualities). He was not a sophist, but his many claims about religion (e.g., that if horses believed in gods, then their gods would have the shape and qualities of horses) sound very sophistic (although, it should be added, he apparently accepted the existence of gods). Socrates, who was the teacher of Plato, was sometimes associated with the sophists; e.g., in the famous play, The Clouds, Aristophanes describes him as one of the leading sophists. However, unlike the sophists (or many of them, at least), Socrates did not charge his students, and Socrates defended objective truth and values.       




He wrote almost exclusively in dialogue form (and Socrates is the central figure in almost all of the dialogues). Many of them (including the Phaedo and the Symposium) are regarded as literary as well as philosophical masterpieces. His dialogues are usually divided into three periods:


Early Period (short, concerned with definition, virtue, no definite metaphysical conclusions reached): Crito, Euthyphro, Laches, Protagoras, Meno


Middle Period (the first appearance and subsequent development of the theory of forms): Phaedo, Symposium, Republic, Phaedrus


Late Period (includes extended metaphysical discussions which are self-critical in many respects): Parmenides, Theatetus, Sophist, Timaeus


Little is known of Plato’s (427 – 348) personal life, less even than that of Socrates (470 - 399). He never married or had any children. He established the Academy, the first institue of higher learing, on the outskirts of Athens, and Aristotle was his most famous student. Although he was philosophically opposed to democracy, which was the from of government in Athens for much of his life, he was more opposed to the only real alternative, oligarchy (rule by a select few).


Plato wrote about many things. The dialogues are concerned in various ways with a number of interrelated metaphysical doctrines. We will largely confine our investigation to: the theory of forms, the doctrine of recollection (anamnesis), and the doctrine of the immortality of the soul. 


The Apology

This work describes the trial of Socrates, Plato’s teacher. Socrates explains that the Oracle of Delphi (a priestess at a famous temple who presumably channeled the opinions of the god’s) had stated that he (Socrates) was the wisest person (or, more accurately, that no one was wiser than Socrates). Socrates did not believe this, and so he tried to show that the Oracle was wrong by finding a person who had more wisdom and knowledge than he did. What he discovered, however, is that everyone he interviewed thought they knew many things, but, in fact, did not. Hence, Socrates discovered that he was indeed the wisest man because he knew one thing that all of the learned Athenians that he had interviewed did not know, namely, that he did not have knowledge about the things in the world, thus making him wiser. One of the charges brought against Socrates at his trial was that he was corrupting the youth of Athens with his remorseless questioning, a questioning that people interpreted as trying to embarrass or damage leading intellectuals and statesman. Hence, Socrates defense is that he was not doing this philosophical questioning with the intention to harm people, but merely to determine if the gods were correct in claiming that he was the wisest person. Whether or not Socrates’ defense was based on an actual event, or just a story to appease the jury, remains unclear.



In this work, Socrates argues that it would be unjust to flee Athens and try to escape his punishment (of taking poison). Since he freely accepted all of the laws of Athens during his life, and took part in all of the benefits and privileges that these laws of Athens had to offer, it would be unjust to the state to run away once those very same laws now rule against him.



The Meno is concerned with virtue in large part, but our attention will focus on Plato’s theory of recollection. Plato describes what can be called his “paradox of inquiry”: How can you learn anything if you don’t already know what it is? For if you don’t know what it is, then you won’t know when you have found it. On the other hand, if you do know what it is then there is no point in inquiring (80 d-e). Solution: the soul is immortal and “All Inquiry and all Learning is but recollection” (81e). Therefore, the soul has already learned everything, which it now only recollects: in effect, there is no learning, only recollection. Plato demonstrates this with his “slave boy example” (82b – 85d). Through asking a series of questions (the Socratic method), he gets the boy to realize that his former opinions of a certain geometrical property (how do you construct a square with double the area of a given square?) are wrong, and then he gets the boy to acknowledge the correct answer. In the end, Socrates says that the boy has learned the correct answer without his “teaching” the boy anything, that is, by asking questions and drawing out what the boy “already knows”. It is true, of course, that the boy is prompted by Socrates questioning (in other words, he doesn’t get the knowledge all on his own), but Socrates doesn’t tell him the answer either. Overall, it seems unwarranted to conclude that the boy knew the answer all along, and is just remembering what he already knew. In fact, how can you tell if you knew something rather than having recollected it? Wouldn’t it be good enough merely to have the disposition to recognize the correct answer (a view that Aristotle seems to hold)? But, in that case, immortality is not required.



The Phaedo presents Plato’s theory of the Forms, where, put roughly, Forms are abstract concepts (such as “human”, “red”, “square”, etc.) that exist as real entities in a timeless realm beyond the material world (so they are sort of like minor deities). They are eternal, perfect and changeless, and are the basis of our knowledge by recollection.

Socrates explains that philosophers despise the body, that is, the pleasures and needs of the body. The philosopher should concern himself with the care of the soul alone (64e). For the body is an obstacle to gaining knowledge since (i) the senses are often mistaken (65b), and (ii), the desires of the body distract us (65c). We approach knowledge only in pure reasoning (65b). Along with beautiful things and good things there is the Beautiful itself and the Good itself. For example, all things that are beautiful are beautiful because the “partake” in (share in, are images of) the Form of the Beautiful. Likewise, all red things are red because they “partake” in the Form of Red, etc. The Forms explain why objects are similar (e.g., why all red things resemble each other in their redness), and how we acquire conceptual knowledge (e.g., redness as a concept, which we can think about in the absence of any red thing). The Forms are understood by the mind (soul) itself, not the body (65d-68d).


Is the soul immortal? Cebes suggests that maybe the soul dies with the body. Socrates argues that immortality is based on opposites coming to be from one another (70a-72e). In short, all things with opposites come to be from their opposites (larger from smaller, cool from hot, waking from sleep, for example). Living is the opposite of dying so living and death come from each other. So, our souls must have existed before we were alive: “the souls of the dead must be somewhere whence they come back again”. Part of Plato’s justification for this argument is that something cannot come from nothing, and if things proceeded only from life to death, then now everything would be dead. Replies: The opposite of living is not dead, but not-living (not-existing), so the living can come and go from non-existence. Also, these concepts might be conceptually interdependent, but that does not mean that actually require one another in actuality. For example, someone could stop being awake by going into a coma or dying.


Recollection of the Forms is also used to prove immortality (72e–77a; these arguments are different from the slave boy example in the Meno): since recollection implies previous knowledge, hence the soul must exist prior to the body. Plato argues that we know that all equal material things are deficient in some way, and so there must be an Equal that we learned before. A better example might be a chair that we have never seen before, but which we immediately know is a chair upon first seeing. How do we know this? Plato’s answer: we have knowledge of the Form of the chair. Plato argues that knowledge of the Forms was gained before birth and lost at birth (rather than having always been possessed). But what about life after death? Simmias suggests (77b) that perhaps the soul is scattered after death, even if it exists before. Socrates first answer is to repeat the idea that life comes from death and death from life. But, he goes on to argue that if there are two worlds, then the soul must be at home in the world of the Forms, not the world of particular things. The Forms are unchanging, unperceived, and eternal. Particular (material) things are changing, perceived, and temporary. He now argues that the body is more akin to the world of particulars, whereas the soul is more akin to the world of the Forms.



There is much in the Republic, but we will only investigate the divided line and the allegory of the cave.


Divided Line: Plato uses the divided line to compare types of knowledge and types of objects (Being). At the bottom, moving to the top we have: for knowledge, (a) opinions and illusions, (b) beliefs about material things, (c) mathematical reasoning and theoretical science, (d) philosophical understanding; for Being, (A) shadows and reflections of physical objects, (B) physical objects, (C) abstract mathematical objects, (D) Forms (especially the Form of the Good, which is the basis of all of the other Forms). For the line, (a) is linked to (A), (b) to (B), etc.


The Allegory of the Cave: Socrates describes a scenario in which a cave is inhabited by prisoners who have been chained and held immobile since childhood, so that they can’t move their heads and are thus compelled to gaze at a wall in front of them. Behind the prisoners is a fire, and a stage upon which objects are placed that cast shadows on the wall that the prisoners must watch, and which they don’t know are mere shadows. Socrates suggests the prisoners would take the shadows to be real things, since these are the only experiences they have ever had. Socrates then supposes that a prisoner is freed and eventually leaves the cave, and experiences the real world as it really is (especially the sun). Eventually, he returns to the cave, but he cannot describe the world as it really is (because the prisoners have no idea of what he is talking about, of course), and the rest of the prisoners therefore make fun of him. Plato uses the allegory of the cave to describe the plight of the philosopher, who can grasp the truths of reality through the soul’s use of reason (which is analogous to the freed prisoner leaving the cave and seeing things as they really are), but is powerless to describe the truth to the people who haven’t reached the same point of enlightenment. It unclear how to interpret all of the aspects of this story, but the sun might represent the Forms (especially the Form of Good), whereas the shadows represent material objects.



This very complex and enigmatic dialogue puts forward a number of difficulties with Plato’s theory of the Forms. One problem raised involves the “participation” of the Forms in material objects. How does this work? Plato argues that the Form is totally present in each object: e.g., the From of Red is completely present, as a whole, in each red object—but how can that be? How can the whole of Red be in many separate red things at the same time? Parmenides suggests that maybe only a part of Red is in each red thing, but this raises problems of its own. If the Form of Large was in many large things at the same time, then some of these large things will likely be larger than others, but than a part of Large would be larger than another part of Large: yet, how can the Form of Large be larger than itself? That seems like a contradiction. The biggest problem raised, however, involves the regress problem (called the “third man regress” in modern discussions). The difficulty seems to be based on the basic reasoning that underlies the theory of the Forms: if many different things are similar in a certain way, then it must be because these separate things share a common thing, which is a Form, and this Form is the basis for the similarity that we observe among those many, different things. But, one could then go on to generate a new similarity between the many similar things and the Form itself (that supposedly explains the similarity of those things), and, by repeating this process, one could generate a new Form over and over again (to infinity). For example, if many large things are large because they share a common feature, Largeness, than one could take the Form of Large, call it Large(1), and place it alongside the many large things—Large(1) and the many large things would now share a feature, call it Large(2), since, according to the basic reasoning underlying the theory of Forms, similarities are explained through the use of Forms. Hence, Large(2) explains why Large(1) and the many large things are similar. But, then one could place Large(2) alongside Large(1) and the many large things, and so this new similarity must be explained by invoking a new Form, Large(3), etc. Conclusion: Plato’s theory of the Forms leads to an infinite regress of Forms without, supposedly, ever fully explaining why the many large things are similar. It is unclear what conclusion we should draw from this dialogue: towards the end, Parmenides (the character in the dialogue, that is) seems to hint that the theory of Forms can still be defended or upheld, and thus some have reasoned that the criticisms of the Forms in this dialogue do not represent the rejection of this theory by Plato, yet, others have drawn that very conclusion (i.e., that Plato had turned away from this theory of the Forms).



This is probably a late period work, and gives a unique theory of the creation of the world. The Timaeus brings together parts of Plato’s theory of the Forms with ideas that resemble some of views of the earlier Presocratics, and even the Pluralists. We will focus on the three-part division of Plato’s cosmos, however, since this is one of the major contributions of this dialogue.


Plato’s 3 part division in this dialogue is as follows: (i) The material world, or that which “comes to be”; (ii) that in which the material objects "come to be”—which is space, or the “Receptacle”, as Plato calls it; and (iii) the Forms, since all material objects are imitations, or copies, of the Forms. (That is, the Forms are eternally existing “beings” which are, essentially, perfect concepts that exist in a world outside of space and time and are the perfect “models” by which all objects are made to resemble, but they are not perfect copies.) It could be argued that the Receptacle is the “place” of all objects (i.e., a container in which all material objects exist), and it also functions as the “one” thing which underlies all change (and so this brings us back to the concerns that motivated the Presocratics). The reasoning seems to be the following: since everything that exists must exist in some place, the Receptacle (i.e., space) is the collection of all places. But, Plato’s theory actually suggests that matter is not separate from space: objects are “formed out of” the Receptacle, and he gives the example of putting a seal into hot wax (so that the image of the seal is contained in, or exhibited by, the wax). Space is thus like a thing or substance from which the copies of the Forms are made. But, Plato says the copies do not possess the properties of the Forms: it receives and makes the copies, but does not become like the Forms themselves (for example, the Forms are eternal but the copies of the Forms in the Receptacle are not). Hence, the example of the seal in the wax is quite accurate, since the wax (like the Recepticle) can take on many different shapes. By this process, the Receptacle functions like the “one” that underlies change (and Plato gives examples of the elements, earth, air, fire, and water, coming to be and passing away in the same parts of the Receptacle). Plato also suggests that the Receptacle and the things in the Receptacle can interact in some way: the copies of the Forms cause motions in the Receptacle, and this motion of the Receptacle causes, in turn, motions of the copies (such as the basic elements of matter). The Receptacle also sorts out the motions of the elements into their natural regions in the cosmos. 

Part of the Timaeus’ plan is to give a cosmological story of the creation of the world. God, which is called the “Demiurge” in some translations, comes across a world of chaotic flux. The Demiurge puts order and structure into this chaotic world by using the Forms as a model for the creation of the things (elements, bodies, etc.) in the Receptacle. By this means, the Demiurge orders the cosmos.




Aristotle (384 – 322 BC; forty years younger than Plato) was the most famous student of Plato, becoming a leader in Plato’s Academy, and eventually opened his own school, called the Lyceum (and he also tutored Alexander the Great). Aristotle’s influence on philosophy is as great, and likely greater, than Plato’s. His approach to philosophy provided the background to how philosophy would be done, up to the present day, in fact (even if many of his particular ideas have long been discarded). Comparison to Plato: more empiricist; less dualist; less literary; more analytical; less dogmatic; more naturalistic, but still theological.


On the Soul (De Anima)

The early Greek thinkers (Presocratics) tended to think of the soul as the source of life, the vital force of things, rather than as a sort of independent thing or substance. Indeed the Latin word for soul (anima) is the root of our words for life (animate). That changes with the Pythagoreans and certainly with Plato, who in the Phaedo begins with the traditional conception of the soul as “the source of life” and then provides a philosophical argument that such a thing is necessary deathless and indestructible. But Aristotle seems to return in some ways to the more traditional, less transcendent, viewpoint. Indeed, he thinks that study of the soul “turns out to be a task for the student of nature” (403a27). Thus, he approaches the problem of the soul at least in part as problem for empirical psychology and biology. The goal of “On the Soul” is to figure out the nature of the soul, for example, whether it is a substance (thing) or attribute, matter or form, potentiality or actuality, simple or divisible into parts, and whether there are different kinds of souls for different kinds of beings (402b5). And we need to determine which functions of the soul belong to it distinctively (e.g., understanding) and which belong to it only as related to a body (e.g., sensation, emotions). He seems to think the soul is “separable” if and only if the soul has distinctive functions or affections, i.e., not related essentially to body (403a15). He also seems to think emotions (such as fear, pity, joy, loving, hating) require a body because “whenever we have them the body is affected in some way” (403a17). He says we should say that the person feels pain and thinks by the soul, not that the soul thinks or feels pain (408b10). He suggests that although things like perception and recollection end or begin in the soul, they do involve the whole human being. Aristotle does not think of the soul as a single, indivisible substance, as would Descartes; rather, there are a variety of kinds of souls and parts of the soul. So we need to treat each of these kinds and parts specifically. Nevertheless, he says that the soul can be thought of generally as what makes some chunk of matter a living thing. His account of this is based on his theory of things as being composites of form and matter. Since the body is matter, the soul must be what makes this body a certain kind of living body. Thus, he says, at 412a20, that “the soul is the form of a body that is potentially alive”. The soul makes this potentially living body actually a living body. So, a living body is a compound of soul (form) and matter. It follows that dogs, cats, worms, plants, and people all have souls since they are all living bodies (412b5). Are the soul and body one?: They are one in the same sense that the wax and seal are one (or the copper and the statue) (412b7). And, as such, the soul is not separable from the body any more than sight can be separated from the eye. “Soul is not a body. . . but requires a body” (414a20). One would be making a big mistake, according to Aristotle, to say that the soul just is the body considered as matter, since the form is not just the matter that it informs. To say that the soul is the body would be like saying the house is the pile of bricks or that the “seal is the same as the wax” (412b8). And also, we would have no way of explaining the difference, he would say, between a living and a dead body.


As noted above, Aristotle seems to have accepted that some forms are separable from bodies, such as geometrical objects which can be separated by abstraction from bodies. What about souls? His answer is that souls are not separable. For certain of their “affections” (such as emotions, fear, hate) require some body and faculties (perhaps this is more obvious in the case of nutrition, movement and sensation) (403a20). Furthermore, a living animal of certain kind has parts which are the actualities of certain organs (the seeing eye)—the soul is not separable from the body anymore than my house is separable from its bricks and wood. In short, Aristotle links the soul to the body, and thus he rejects Plato’s view that the soul can exist apart from the body.


Since there are many different kinds of living things, with many different faculties, just as there are many different figures with different numbers of sides, Aristotle concludes that there are many different kinds of souls (414b27-30).


The Nutritive Soul: This, he says, is the mostly widely shared part of the soul since it is what makes all living things alive. Its main functions are generation (growth) and nourishment. Generation is the most natural function since living things aim to produce another that is the same as itself in order to share in the everlasting and divine (415a28 – 415b7). As regards causation (see the discussions below in the Metaphysics): the soul is formal cause (the reason this is a living thing); final cause (the living body is for the sake of the soul); and efficient cause (soul is cause of motion, alteration, change) (415b10-20).


The Perceptive Soul: What distinguishes plants from animals? A first guest might be locomotion (self-movement). Aristotle does think that there is a locomotive soul, but he rejects this as a definition of animals because things like oysters and scallops don’t move (and, furthermore, some plants seem to move). Again, some animals have imagination in the sense of mental images not gotten directly from sensation – like dreams). Rather what all animals have is some power of sensation (not all of the senses, but at least of touch). Aristotle is the first philosopher to give serious attention to the problem of how a living thing could perceive the world. This is a very difficult problem that continues to be of concern to philosophers today.

What is perception? How do we explain how I or an animal can somehow reflect or represent the external world? Aristotle has a very straightforward theory. Consider how it is that a picture or photograph represents a part of the world (such as an apple). Basically, it does so by actually taking on some of the properties of the apple, such as its shape, color, etc. Aristotle proposes a similar account of the soul’s ability to sense. When perceptive soul perceives the redness and circularity of an apple, it is affected (moved) by that apple. Before the perception, it is not like the apple, but is only potentially like the apple; but after the perception it is actually like the apple in these ways (418a5). The idea is that the soul comes to perceive the apple by somehow coming to resemble it, to share its features, much as a picture would represent the apple. In sensation the sense organs actually take on the “perceptible forms” of the apple, but not the matter (424a 1-20). The perceptible form is not the form of the apple, but the things we perceive in the apple: color, shape, etc. Problems with this conception: (1) bodies aren’t really red, loud, etc., since they vary with perceivers. (2) red, for example, doesn’t fly through the air to our sense organs; (3) my sense organs don’t literally become red.


The Intellectual Soul (Nous): appearance is not the same as perception since we have appearances in our dreams and imaginings; some animals have perceptions but not appearances (bees and grubs don’t dream; perceptions are true but some appearances are false) (428a10). Appearance is not the same as belief since belief requires conviction and, hence, persuasion and reason (he says you cannot believe something unless you find it convincing) (428a20). Appearances are not beliefs combined with perceptions, since our appearances can be false while our beliefs are true (based on the same perception; e.g., the sun appears only a foot across) (428b4). Appearance = ‘a kind of motion that only things that have perceptions can have’ (428b10). He says appearances are a kind of motion, presumably a motion in the brain, but doesn’t really solve the problem of their relation to perceptions (428b11). Besides sensing the world, we also know it. Whereas sensing involves the soul taking on, in some manner, particular properties of things (“sensible forms”: particular shapes, colors, this man, etc.), knowledge involves understanding general concepts or universals or “intelligible forms” (redness, apple, triangularity, humanity) (417b20). The ability to reflect on general concepts is what distinguishes humans from animals, and this is the role of the intellectual soul.  Now this difference suggest to Aristotle some important distinguishing features of the intellectual soul, as compared with the sensitive soul, which seem to suggest that the intellectual soul is more likely to be separable from the body. (1) The senses are restricted to their proper and common objects, while the intellectual soul can know “all things”. It is pure potential (429a20) and so does not have an organ, or it would take on some of the organs properties. In this sense the intellectual soul is “the place of forms”. (2) Sensation depends on specific sense organs. We need eyes to see and ears to hear. But we don’t need these to think about shapes or whatever. In this sense, intellection is not so dependent on the body; it is not mixed with body (429a25). That is why the sensitive soul can be damaged by intense sights or sounds, while the intellectual soul is not damaged by thinking about difficult concepts; on the contrary it is made more intelligent (429b5). (3) The sensitive soul perceives only this or that particular color or shape. But the intellectual soul apprehends redness or triangularity, which are universals and not reducible to any particular thing. So the intellectual soul is not the form of any particular body. In this way it is also not so closely tied to the body (429b10-20). In what sense exactly is the intellectual soul separable from the body? In general there is a difference between flesh and being flesh, the straight and being straight, etc. We use the sense organs to discriminate the former, and the intellect to discriminate the latter. As the straight is separable from objects, so the intellectual soul is separable from the body (429b23). His view seems to be that the intellectual soul is separable from the body in a purely conceptual sense: since we can think of being straight (as a form or essence) apart from the straight (straight objects), so the intellectual soul which becomes these things can be thought of (as a form) apart from the body it is the form of. But notice this is purely a conceptual distinction: he would not say redness is really (spatially) apart from red things, or that the house is really apart from the bricks, and he would not say the intellectual soul is really apart (as a substance) from the body. At 430a5-25, he distinguishes between two parts of the intellectual soul: one is passive (which we have just been talking about) since it becomes the things it thinks about. That is, before understanding “the straight” it that soul is pure potential, like a blank writing tablet (430a1). The other is productive in two senses: (i) it is the source of the universal forms which are gotten by abstraction from perception of individual objects and which the passive intellect receives; (ii) it can act in the sense of bringing about changes in its thoughts and choosing to think about this or that. Now, Aristotle argues that only the active intellect is really immortal and truly separate from the body. For it is a creator and unaffected, while the passive intellect is acted upon. Also, it does not rely on the existence of any ideas for it to be what it is, i.e., pure actuality in thought. Therefore, since it depends on nothing and is affected by nothing, it alone is immortal. However, this is hardly a consolation for those who want to survive personally after death. For, as Aristotle says, the active intellect will not remember anything after the body is gone, for it does not receive ideas of things, but acts upon them (what the active intellect really is, in the afterlife, is unclear: it may be one great mind or something). What is the soul’s relation to God? How is it distinguished from other active intellects? This was a major issue for medieval philosophers. (Practical) intellect does not move anything without desire (433a24). But desire can be in accordance with intellect or mere appetite or appearance (the former is never wrong but the latter sometimes is, 433a28). Reason and appetite can be in conflict only in the case of beings with a sense of time: reason draws us to what is to come while appetite draws us to what is present (433b7). The ultimate object of desire is the first mover since it moves without being moved (433b12). Animals with reason and deliberation are able to compare appearances and pursue the good (whereas non-rational animals have appearance but not reason or deliberation) (434a10).



Book One (Alpha): He opens the Metaphysics with the optimistic declaration that “All human beings desire by nature to know” (980a21). That’s why vision is our favorite sense.


Experience: Animals have perception, appearance and memory to varying degrees, but only humans have “experience” (by which he seems to mean inductive memory: we can see this particular as similar to this). For example, a certain person has considerable experience as a medic, a day-care provider or attorney (981a1). Craft (techne): knowledge characteristic of a craft, and (demonstrative) science, arises when experience results in a “universal view about similar things” (981a6). For example, we can know by experience that this medicine benefited a particular person, but by craft we know it benefits anyone with a certain sort of disease. Craft involves a “rational account” and knowledge of the “causes” of things, and so it is judged to involve “understanding” and wisdom more than experience. That’s why we take ability to teach as a sign of knowledge (981b7).


First Causes (982a-b): Wisdom is the knowledge of first causes or principles, i.e. universal science, which is: most universal, most difficult (most removed from sensation), most exact (dependent on fewer assumptions), valued primarily for its own sake (e.g., philosophy vs. business; math vs. engineering), most basic (other sciences derived from them), and concerned with the end or purpose of things.

Philosophy is the most divine, because philosophy is the most “free science”: it alone exists for its own sake, perhaps it is really beyond human capacity (982b28). In fact it is divine in two ways: (i) gods themselves are causes and (ii) so they would be the most likely to be interested in causes (983a10).


Aristotle’s account of causation involves four types of causes: He gives the example of a bronze statue (say, a statue of a particular person), and considers the four causes with respect to this object. (1) The material cause, which is what it is made of (this piece of bronze). (2) The formal cause (as form or essence), which would be the shape of the statue, i.e., the shape that resembles the person. Importantly, Aristotle’s “forms” are not Plato’s “Forms”, since Aristotle’s forms exist only in the object(s), and they do not exist in a sort of heaven outside the material world, as they do for Plato. (3) The efficient or agent cause, which would be the sculptor that makes the statue (and would be the principles of motion/change in natural objects). (4) The final or end cause (as in purpose, or teleology), which would be the purpose that the statue serves (such as a monument to the person, or decoration, etc.).


Aristotle against the Pre-Socratics and Plato: Aristotle is the first real historian of philosophy, and, like any historian, his historical account is in terms of terms of his own system, in this case the four causes (for these are the fundamental principles of things).


Aristotle explains that the Presocratics attempted to explain everything in terms of one or more material causes or principles (water or fire or air, which remains fundamentally the same through all change, as Socrates remains the same when he comes to be good; 983b8). But they failed to explain why things come to be just as they are: they can explain what the world is made of, but they can’t explain why a world of this sort came to be (983a20). That is, they don’t provide the efficient cause of change. Anaxagoras and Empedocles attempted to explain the cause of change in terms of non-material principles (mind and love/strife, respectively), and so this was an advance over the earlier thinkers because they mentioned two of the main causes (material and efficient). All these philosophers lack the notion of a formal cause. i.e., the reason something is what it is. That is what Plato discovers, as represented by his theory of Forms. Aristotle’s attitude toward Plato’s theory of the Forms is often rather dismissive, but his debt to Plato is enormous and they certainly had more in common with each other than either had with the Presocratics. Plato agreed with Socrates about the need for universal definitions of things and wanted to extend this from the moral realm to everything (and he says that Socrates’ was strictly interested in ethical issues). The problem is that Plato also accepted the doctrine of that the material world continuously changes, and ideas or concepts apply to another, unchanging, sort of thing (i.e., the Forms) (987b5). Aristotle was similar to Plato in being anti-materialist. That is, they both rejected any view which said the world could be explained strictly in terms of matter and some principle of change (as efficient causation). Furthermore, they agreed that what was needed was a notion of the form or essence of a things: one needed to appeal to something other than matter and particulars to understand how things can be a type of thing (such as a human, dog, doctor, etc., which are types of things), and not just a lump of matter. The atomists, for example, argues that things are made of atoms, but Aristotle would claim that this explanation is not sufficient, since something must explain the unity and function of the object (i.e., the object is more than just a collection of atoms, but a whole or unified thing that can gain/lose atoms over time but still remain a whole thing, e.g., a man). For Aristotle, the form (essence) is that unifying aspect of a thing. But, Plato and Aristotle disagreed about what precisely forms are: Plato made them entities that exist apart from material world in some kind of Platonic heaven, but Aristotle concluded that they can only exist in matter (although there are a few exceptions, such as God or anything else that does not depend on matter). In short, Plato’s view was unacceptable to the scientific mind of Aristotle. Of course, Aristotle has the problem of understanding how something that is concrete and particular (an apple) could have something that is abstract and general (the form of apple, or apple-ness). Nevertheless, Aristotle’s conclusion that forms only exist material things (except for God) would seem to equivalent, in modern times, to claiming that they are “properties” of bodies.   


Against Plato’s Forms: for Plato, Forms are formal causes (an apple is what it is because it “participates” in, or imitates, the Form of Apple). But Aristotle complains that the Pythagoreans, and perhaps also Plato, “left it to others” to explain the nature of this participation (987b14). Aristotle offers several problems: Plato’s theory of the Forms implies that there can be a Form of “negations” (such as donut holes); Forms of things that have perished or have never been (unicorns, etc.); Forms of “relations”, such as “beside the door”, or “sister of x”, etc., and he also mentions the Third Man argument discussed above (990b18). Aristotle also argues that Forms do not really explain why things come to be (991b3-10).


Book IV (Gamma): Philosophy as knowledge of objective reality. Debates about relativism, whether there are objective standards of knowledge, truth and values, are as old as philosophy. Aristotle attempts to refute relativism in this part of his work. He mentions Protagoras, the Sophist who supposedly said: “Man is the measure of all things.” Plato was also opposed to relativism, and such a view (i.e., objectivism, which opposes relativism) has been characteristic of Western Philosophy (with occasional exceptions, such as Postmodernism).


The Principle of Non-Contradiction (PNC): one way of stating relativism is to say “if X believes P is true (or if X’s culture regards P as true), then P is true”. In other words, there are no independent requirements for truth other than conviction or perhaps general agreement. Example: if I believe the earth is flat, then it is flat, and it is also flat for everyone else in the world (i.e., it is really flat: it is not just flat in appearance to me, since that would mean that its true shape may be unknown to me). Now, Aristotle argues that such a view leads immediately to the abandonment of the principle of non-contradiction (PNC): it is impossible for a thing to have a property and lack it at the same time and in the same way (or, for any statement P, it cannot be the case that both P and not-P are true). Given relativism, if I believe X, and you believe not-X, then X and not-X are both true, which violates the principle of non-contradiction (PNC). Aristotle gives a number of arguments to show that PNC must be true, and that it is one of the most basic principles, so that one cannot reject PNC without absurd consequences (thus relativism is false, since relativism rejects PNC). One arguments he offers is that if someone rejects PNC, then the person is like a “vegetable”, since they cannot communicate with you (i.e., provide information to you): everything they say would be both true and false, and so they cannot communicate with you at all. Also, you couldn’t survive if you deny PNC: e.g., there is a bus coming down the road, but it’s also true that there isn’t a bus coming down the road, so you walk out into the street and get killed! Aristotle also argues that one cannot prove the PNC, since any attempt to prove it must also use it in stating the argument, so the PNC cannot be proven in the same way that other things can be demonstrated to be true. At best, all Aristotle can do is to demonstrate that the denial of the PNC leads to absurdities; but, also, that anyone that tries to deny PNC must assume it, and so they contradict themselves: i.e., if someone tries to make an argument that the PNC is false, then they will have to use words and make statements in a clear and non-contradictory way in attempting to make their case, but that means that they will need to make statements that have only one meaning, say “P”, and not “P and not-P” at the same time and in the same way; hence, in order to argue against the PNC, a person needs to assume the PNC in order to make their case against it, which is a contradiction.       


Appearance: like Plato, Aristotle is concerned to refute the view that reality is sensory appearance. Such a view would lead to relativism since sensory appearance obviously varies across people and with time. He says people have defended this view because they have wrongly assumed that what is known is simply appearance. His reply begins with a lecture about relativism (1010a) and how it can discourage philosophy. But his main point is that the view depends on a mistaken view about knowledge: knowledge is not of perceptible things but of universals (his concept of forms, not Plato’s Forms) and ultimately about the ends of god (unmoved mover). Furthermore, even it is true that nature is continuously changing, it does not follow that nothing is “real”. For to say that X changes presupposes that X remains across the change. He seems to think that “everything changes” actually makes no sense (1010a20). He also says that change is not as ubiquitous as is often assumed and that in any event there is an unmoved mover. He also supplies other arguments against the skeptics (1010b). Some argue for relativism since things appear different to different perceivers (healthy, sick; distant; near). Reply: but the senses cannot be wrong if they stick to their proper objects (e.g., if we only say what a color is on the basis of sight, not with respect to anything else); and, even if there is disagreement about colors, sounds, etc., this is only about the subjects (matter), not the form (1010b 20-25). How do we know we aren’t dreaming? Reply: but people don’t act as it they regard their dreams as true.


Book VII (Zeta): “Being” is spoken of in many ways: but the primary being is substance (what it is) rather than quality, quantity, relation (what is true of it), since all other things are beings only because this is being (1028a30). The basic ideas seems to be that all other ways of being are aspects of things (while substances are basic), and none of these other ways of being, i.e., qualities, quantities, flourishing, walking, etc., can be separated from substance. Substances are thus primary (i) in nature; (ii) in explanation, since its account is involved in the account of all other things; and (iii) in knowledge, since we know most when we know what a thing is rather than its qualities or quantities (1028a35). So the science of Being effectively reduces to the science of substance. It seems that substance should be matter since it seems that everything else that exists (except gods) depends on modifications of matter; but matter in its own right is what has no qualities or quantities or any other properties (1029a22), and so it impossible for matter (in this sense) to be substance because substance seems to be primarily “a this” (a separable thing) (1029a28). That is, if matter in itself has no properties at all, then it’s hard to know what remains left that one could point to as a separable thing.


The essence of F (where an essence is a form) is what F is in its own right (1029b14). But, not all things that belong to a thing in its own right are essences, e.g., the paleness of a surface, because being a surface is not the same as being pale. That is, even if all and only surfaces are both pale and smooth, being pale is not the same as being smooth. Also, consider a composite property, like “pale man”: there is no essence corresponding to such a composite (1029b30). More fundamentally, a pale man is not essentially a “this”. Furthermore, essences correspond to things that are not “said of” other things, i.e., they are primary. Essences  belong primarily to substances and only derivatively to things like qualities. Definitions in the primary sense are of things that are one, but not merely by continuity or composition (like the Iliad or the pale man). Aristotle concludes that the individual thing is identical with its essence.


Book XII (Lambda): Substance as Divine Intellect. Around 1071b 1-10, Aristotle argues that there was always motion since there was always time. That is, since time is the measure of motion, if there is no motion, then there is no time; Aristotle thinks that this is a contradictory outcome (so any view that holds that time could go out of existence must be rejected). Also, only substances move, so, if there are no substances that move, then there is no time. Now, since substances (other than god) are a mixture of potentiality and actuality, and potentialities may never occur, Aristotle concludes that the ultimate source of change must reside in a substance that is all actuality (i.e., god, which is also the unmoved mover) because all the beings that contain potentiality could go out of existence, and thus there would be no world or time. Plato’s Forms cannot be the source of this motion since they do not seem to initiate change. The source cannot be material, since motion is everlasting, and material things are not everlasting (also, he argues that the final sphere of the heavens, which is an everlasting material thing, cannot be moved by another material thing, since there are no other material things beyond the final sphere of the world). So, Plato and the atomists are incapable of explaining the source of motion and change (1071b33). Rather the ultimate source of motion is the first or unmoved mover (1072a15). But the first mover moves without being moved itself (for if it was moved, the question as to what moves it, or its parts, would arise). So how does it move? Answer: the first cause moves the world as an object of desire or love or understanding/thought (1072a27), since, as we know with respect to our own mental states, our own thoughts move our bodies but our thoughts are themselves not motions. The mover is in a state of permanent actual knowledge/thought (1072b15). So the unmoved mover is the final cause of motion (at least in the heavens). What is the unmoved mover’s activity? Answer: It is clearly not sense perception or knowledge (even of universals) since these involve matter or at least passivity or potentiality, and are dependent on other things (also, the unmoved mover is all actuality, and has no potentiality, as noted above). Furthermore, god would not think about things which are not worth understanding, so god must think about thinking (1072b25-30), or, god’s thoughts concern god alone. What does this mean? Is god merely examining his own life, as any good philosopher should (i.e., the unexamined life is not worth living), or is god just self-absorbed and narcissistic? Is this a concept of god that resembles in any way the Western conception of God?


Hellenistic Philosophy

This period in ancient Greek philosophy coincides with the Hellenistic period, which starts with Alexander’s death and the rise of Greece as an empire, roughly 3rd century BCE to 2nd century CE. The period is marked by the development of new schools in Athens and various changes in perspective brought about by the changing fortunes of Greek society and politics. 



Epicurus (341-270) adapted the atomist picture of the world for his own unique philosophy, which is aimed at pleasure (which he identifies with the absence of pain). He retained many of the beliefs of the atomists, such as the view that everything that exists is comprised of atoms, i.e., there are an unlimited number of indestructible, eternal atoms of various shapes and sizes that are always moving and combining in an unlimited void to produce the visible world. Like some of the earlier atomists, Epicurus believed that there are soul-atoms dispersed throughout our bodies (so the soul is material). He thought that this world view, and the study of nature in general, brings calm to life more than any other approach. He accepts as a basic principle that nothing comes from nothing, and that the universe is a closed system (i.e., nothing extra can come into the universe to change things). The universe is infinite in time and space (but containing many finite worlds, a view that was denied by Aristotle). His approach was also empiricist, since he held that sense experience is certain in itself, whereas atoms are known only by analogy from experience. On issues related to ethics and the meaning of life, Epicureanism was often accused of supporting a self-indulgent hedonistic life-style, but, as noted above, the Epicureans were really motivated to search for a life free of pain. In fact, they, thought that only some desires are natural and necessary (eating, drinking, sleeping), whereas other desires are natural and unnecessary (fine food and wine, sex), and other desires are empty or groundless (immortality, divine reward, fame). Hence, in order to avoid pain, passionate pleasures should be avoided. Like Socrates in Plato’s Apology, Epicurus holds that death is nothing to fear (since, when death comes, we won’t be around to feel pain anymore). He believes that the gods exist, but they are material beings, and they do not concern themselves with humans, thus we don’t need to worry about the gods.



Zeno of Citium (333-260 BC) is the founder of this school, along with Cleanthes (330-230 BC) and Chrysippus (280-206 BC). The Stoics believed that everything that exists is corporeal (matter), but they also held that the material world is like a living being that is both rational and has a divine active principle (soul or pneuma): matter is itself passive, so the active principle (soul) provides the activity of the being (much like Aristotle believed). They reasoned that, since something that is non-material cannot act, hence the soul must be material (for it acts on passive matter). They hold that the four elements make up the world, but, at least for later Stoics, the divine active principle generates the four elements (although some view the element, fire, as the active principle). The active principle is deterministic (or fatalistic), so that nothing happens in the world by chance (moreover, the world is governed by deterministic laws). The world is also a finite sphere in an infinite void (hence they accept the existence of the void in addition to matter). The relationship of a human soul to its body is like the relationship of the world’s active principle (soul) to the world, furthermore. Turning to ethics, the Stoics believe that the “good” is living a life according to nature; and, for humans, that means that we should live our lives according to reason (since reason is central to their conception of the soul, or divine natural principle). A life lived according to reason is virtuous and happy, whereas unhappiness follows if we don’t live a life according to reason. Since everything happens in the world according to divine necessity, we should accept the things that happen in our life over which we have no control with equanimity, i.e., a noble indifference to the vicissitudes of life (which is one of the ways we define the word, “stoic”, today). Therefore, it is important to strive to live a life that is self-sufficient and does not depend on external things or circumstances that are outside of our control. Hence, since virtue (justice, temperance, courage, wisdom) is within our control, moderation and avoidance of extreme passions and desires is important for happiness.



This school of philosophy, initiated by Plotinus (205-270 AD), was heavily influenced by Plato, but also exhibits the influence of other ancient philosophers, especially the Stoics and Aristotle. Since it includes many features that are different from Plato, it later came to be called “Neoplatonism” (i.e., new Platonism). The main feature of Neoplatonism is its acceptance that everything that exists is a manifestation (in different ways) of the “One”, which is God, although it is described as “beyond being”, and is thus unknowable. The One is the ultimate cause of all other beings. The One is similar to the Form of the Good in Plato (since Plato believed that the Form of the Good is the basis of all of the other Forms). The first “emanation” of the One (i.e., entity that arises from, or is generated by, the One) is Nous (or Intelligence), which seems similar to a conception of God as the intellectual part of an immaterial soul. Nous is both being and thought, and is somewhat similar to the Forms in Plato (but not the Form of the Good). Nous also makes the world perceivable and intelligible for humans. The next emanation, which is the product and the image of the motionless Nous, is the World Soul (or Soul), which is also immaterial. The Soul is closely connected to the material world: it governs the material world but is also related to human souls. The Soul also generates the material (or phenomenal) world. For the Neoplatonist, matter is an inferior type of existing thing, and, absent soul or ideas, is evil (and evil is defined as the absence of good, or as non-being: e.g., darkness can be viewed as the absence of light). The Neoplatonists thought that humans could obtain happiness and perfection in the world, but they also accepted that the human soul is immortal (like Plato believed).       


(Notes completed, 4/26/2016)