Phil 211: Introduction to Epistemology

Oct 15: Introduction to Epistemology

 Last Day

  1. Introduction; why am I here?
  2. Religion; an easy answer? the wrong answer? a different answer?
  3. Worth; intrinsic or earned?
  4. Time and meaning; a world without us
  5. Sisyphus and creativity
  6. Greatness; philosophical elitism

To do for next class - 1) Read chpt. 1, we will discuss it two classes from now. 2) What differences do you expect there to be between metaphysics and epistemology? What similarities?

  1. Descartes; meditations; method of doubt
  2. Rationalism and empiricism; responses to Descartes; continental vs. Anglo-American
  3. Liebniz and rationalism
  4. Hume and empiricism
  5. Kant's synthesis and resolution of the debate

To do for next class - 1) Read pp. 21-30 2) Exercise 3 on p.19.


As a simple starting point, we can consider philosophy as a study of two main things: 1) The universe 2) Human nature. All of our preceding discussions in metaphysics can be put into one of these two categories. And, a good metaphysic should have answers for both 'What is there?' and 'How are we related to what there is?' (i.e. What are we?). Though not all philosophers seek unity, most see this as a desirable end. In fact, unifying theories have been the mainstay of philosophy for most of its history. So, it is not surprising that philosophers have often offered theories which are purported to explain both human nature and the universe. But there is more than one way to answer both these questions at once.

The Stoics

The Stoics (founded by Zeno 250BC on his porch) were the first to proposed a simple extension of their cosmological theory to include human nature. They believed (as many do today) that all that is real is material and that this 'matter' was guided by God (or rationality or logos or force) to conform to natural laws. The same fiery reason which pervaded all matter was also thought to be in mankind, as all members of that class are material as well. Thus, in a very real sense everyone has a bit of God (a spark) in them. In fact, that spark is what causes them to move, speak and think. Applying this somewhat mechanistic view of people to the moral realm, they felt that our existence was like that of an actor in a drama. In some sense determined, but still under our control insofar as we could be a good or bad actor. There was a tension in their philosophy such that everything should be determined by 'providence' (the plan of logos or God) yet people seem free to act. Perhaps, they explain, our unique knowledge of the natural law allows us to conform to it and be happy (apathy).


Epistemology (Greek - episteme: to know; logos - study) is the field of study of 'theories of knowledge'. This was the second way in which human nature and the universe can meet in a single philosophy. Epistemology was practiced since Plato's, Socrates' and Aristotle's day, but only gained that title in the 17th and 18th centuries. Despite the antiquity of its problems, it is still on of the most hotly debated areas of philosophy. In the seventeenth and eighteenth centuries, a group of philosophers from Europe began this influential branch of philosophy. You many recognize many of them, including Kant, Descartes, Locke, Hume, and Berkeley. The believe that, since every fact, hypothesis, conjecture, etc. about the universe is something produced by us, perhaps, by studying ourselves and how we come to know these things, we could come to know the universe for us. This is the study of the way in which we know rather than what we know. Unlike Socrates, these epistemologists did not think the study of our nature was just primary, but rather that it was necessary to understanding what parts of the universe were accessible to us. This means questions like: Can we know anything at all? Can we know about things we don't perceive? Can we know about necessary and possible things? Can we know were are not the only mind? Can we know we aren't being continually fooled by a little demon?

There were two central schools of epistemologists, the rationalists and the empiricists. In general, the former were found on the European continent (hence Continental philosophy) and the latter were from the British Isles. Rationalists (Continental philosophers) held that we can know some things just through the appropriate thinking processes. Empiricists, in contrast, held that we can only know things via the evidence from our senses. Many have tried to apply this distinction retroactively to philosophers such as Plato (rationalist) and Aristotle (empiricist) with interesting results. In fact, the distinction often seems pervasive through the history of philosophy. However, it is not clear how it would apply to fields such as ethics, philosophy of art, and philosophy of religion. For others, this distinction is a fundamental methodological one between the sciences and the humanities (discuss).

The epistemological view has led some to posit that there is nothing in the universe except what is perceived by us (Berkeley, William James). Berkeley put it as esse est percipi "to be is to be perceived" (Dr. Samuel Johnson: "I refute him thus"; G.E. Moore - trains). This anti-realist position is, for some, a logical consequence of strict empiricism. Since empiricists claim that all we know comes through our senses, then they are committed to the view that all we know there is is perceptible (But what about all there is - realism is a modal claim: Things would exist even if we didn't percieve them). If something is imperceptible, we have no way of knowing it exists so it doesn't (in any interesting or consequential or non-arbitrary way). For Berkeley it is impossible to conceive of the imperceptible (because you perceive it by conceiving it) thus, all that exists is all that is perceptible (for James, 'pure experience').

So, what kinds of questions do epistemologists ask? (What do I know? How can I know anything? What can I be certain of knowing? What are the limits of my knowledge? What is it to know something? Where can knowledge come from?) Can you name a few different kinds of knowledge? (A priori, a posteriori, propositional, non-propositional, procedural knowledge) What are some examples?

So, what are the two methods to unifying questions of the universe and human nature? (start with universe or start with human nature).

Descartes' meditations

Descartes is perhaps the most often quoted philosopher. We have all heard the pithy "I think, therefore I am". Of course, Descartes never actually wrote that in the Meditations, where he argues most strenuously for it. Nevertheless, it is an accurate portrayal of a central conclusion of his - a conclusion which supports his belief that we can have certain knowledge. Descartes is also famous outside of philosophy for his 'Cartesian' coordinate system which is the standard in much of mathematics. In fact one of his great ambitions was to provide a mathematical foundation for all of science. He was also a teacher of Queen Christina of Sweden (who woke him up to early and caused his death). But for our purposes, it is Descartes method of doubt and his conclusion (the cogito) which are of interest.

Descartes' method

Descartes asks a question: What can I surely know? What can I be certain of if I doubt absolutely everything? Does this question strike you as strange? How would you respond if some one told you everything you experience is just a dream? These questions probably seem less 'far out' nowadays than they did in Descartes day. We know precisely how amazing the human mind can be, how real hallucinations seem and how disorienting virtual reality is (30 mins to change physics models). Nevertheless the questions are odd. Who really doubts that we are different people standing on the planet earth? Well, Descartes tried to. He thought that if he could doubt everything that was at all doubtable whatever was left would be certain knowledge. Once you have certain knowledge, you have unimaginable power to build up a convincing philosophical and scientific system. That was Descartes' ultimate goal.

His method is not simply one of doubt. It is also one of inquiry. He is trying to find something out - what is certain knowledge. He is assuming that there is something we want to know that no one else already knows. Furthermore, his "method of doubt" is not simple doubt, it is absolute doubt. We can not just think "maybe what I'm seeing is an illusion", we have to assert "everything I ever see is illusory" -- and see what we are left with. Anything we can possibly doubt must be doubted. Can you think of something it is impossible to doubt? Perhaps the best way to conceive of absolute doubt is to assume there is an evil demon (a Cartesian demon) whose sole purpose it is to trick you (a grand conspiracy). The evil demon is extremely powerful and so can alter all of your perceptions to make anything look like any other thing. This sounds weird? Well, Descartes imagined this exact situation.

What did Descartes do with this situation? He doubts everything. Absolutely everything? What did he find it impossible to doubt? His own existence. Cogito ergo sum (the cogito). Translated: "I am thinking, therefore I exist". Did Descartes do a good job of doubting? Is it possible to doubt even more? What were the results of Descartes position? (Solipsism; Subject of knowledge is more important than the object).

What is the epistemological turn? (The change in focus from ontology to epistemology instituted by Descartes.) Why is it important? It is important because for 2000 years before Descartes, questions of what exists were seen to be fundamental to all other questions (metaphysics took precedence over epistemology). (Wolff introduces the 'car' analogy with a logical engine). Using Descartes' method, questions of being must be set aside until questions of knowing have a satisfactory resolution. We must not, according to the method, stipulate anything. Nevertheless we must achieve absolute certainty. For many, strict adherence to this method results in absolute skepticism - the belief that we can't know anything. However the purpose of this method (and the resulting skepticism) is not to get us to stop believing (like the skeptics - wagging finger) but rather for us to ponder the relationship between justification and our beliefs. And consider this before we could make claims about metaphysics.

Responses to Descartes

Descartes himself sets up a distinction which runs clearly through many of the responses to his argument. What two kinds of knowledge does he distinguish? (knowledge through the senses, and knowledge from abstract reasoning). Descartes himself comes down on the side of the latter. He uses a thought experiment with wax to show how we are capable of abstraction - an ability which seems to show to him the powers of rational thought. We could imagine everything brought to us by sense being changed, nevertheless we could identify this as the same piece of wax (an intuition of the mind). This is a position of the rationalist.


Rationalists (continental philosophers) agreed with Descartes that logic and math were the models for true knowledge. They felt that all valid knowledge claims rested on the powers of human reason.


Empiricists (British philosophers) disagreed with Descartes and felt that all knowledge comes through the senses. This lead them to a skeptical position in which the felt that no knowledge could meet Descartes certainty criteria. For the empiricists, reason played a role of organizer, not the role of a producer of new knowledge.

Note that we are mostly dealing with the problems of certainty and skepticism. Epistemology, however, is far more vast that this. In fact, it is often broken into sub-divisions of certainty, identification of kinds, justification conditions, truth conditions, belief conditions, and skepticism.


Descartes had offered psychological tests of truth and certainty, Liebniz offered logical criteria. He proposed that the law of contradiction (both a statement and its opposite can not be true) along with the law of excluded middle (a v ~a) is a means to discovering some kinds of truth. He called these truths of reasoning (note: LEM is not accepted by intuitionists). Truths that cannot be so justified are called truths of fact (causal truths?). This second kind of truth can only be established by positing a God - through the principle of sufficient reason, as we have seen (notice the meeting and intimate relation between metaphysics and epistemology).

The tradition of logic had long been associated with philosophy (Aristotle was its inventor) and was the basis for the rationalist claims to certain through reason. Truths of logic are rather compelling, and do not seem to rely on sensory experience for the compellingness - they are, in fact, all tautologies. We need few axioms to get a great many claims. (Short history of logic - Aristotle (& early Hindus), syllogism, Kant presumed it was finished, turn of 20th century new boon, symbolic = sentential + predicate, principia mathematica, set theory, arithmetic, nonmonotonic/fuzzy, boolean ('just an exercise'), logic as the way we think & the way we should think).


Hume followed in the footsteps of Locke by examining the source of our knowledge rather than just the knowledge claims directly. Locke's theory of the tabula rasa (blank slate, usually wax) was intended as an analogy to the state of an infants mind. It is experience that fills the slate up with the materials of knowledge. What does this kind of theory do to our conception of God? (it render's 'God' meaningless) What is wrong with the anti-religious argument? (But we have a concept of God, where does that come from? If we can show there to be an idea there, then tabula rasa is false - reductio ad absurdum. So one thing must give why not tabula rasa?).

Hume took Locke's ideas and made them explicit in his creation of a Newtonian description of mind. What were the 3 main components to his theory?

  1. White paper/tabula rasa from Locke
  2. Copy theory of ideas - How did this work? (impressions vs ideas = immediate, first encounter with sensory input vs. remembered/synthesized/internal perceptions. simple vs complex perceptions - atomic sense impressions vs. combinations thereof (or ideas). Note that all simple impressions correspond to simple ideas (and vice versa) but complex impressions and ideas are not exact copies and we can have ideas that have no corresponding impression).
  3. Atomic theory (as from above) - What consequences are there of this theory? (We can separate the atoms in our imagination).

What are some examples of each of these categories? What examples show the differences that Hume is claiming? What do you think of this analysis? Are there any assumptions Hume is making that aren't explicit?

What does Hume go on to do with this simple theory? (wipes out metaphysics, natural science, and common sense beliefs about the world). How? He attacks our notion of causation. He says no one ever proves that all things must have a cause, they just assume it. But, Hume's powers of doubt are greater than those who hold this position seem to suspect. By applying his theory he thinks we should be able to find such a proof - if it exists. He thinks that we are looking for unalterable relations between ideas, and hope to find causation there (among resemblance, proportions, etc.). However, he claims we can't prove the necessity of causes. Why? He says we can clearly think of things popping in and out of existence without a cause; because this is conceivable, it is actually possible and does not imply a contradiction. Because there is no contradiction, we cannot refute this separation from our ideas. (Notice the structure of his argument... thesis, argument, possible refutations and replies). Why is this denial of causality so important? (so many beliefs are causal, we (and science) assume causal connections to make predictions).

Kant's resolution of the debate

Kant, about a hundred or so years after the debate had begun, attempted a resolution which would dissolve the strong skepticism of the British empiricists. He began similarly to Descartes by positing: "I am conscious". Now Wolff tells us that "introspection reveals and logical analysis confirms" that my consciousness is unified. However, some prominent philosophers of mind believe that this is demonstrably wrong (Dennett). Keep this in mind as we evaluate Kant's discussion. Kant states his starting premise as: "It must be possible for the "I think" to accompany all my representations."

Kant argued that this unity could not be given by experience but must rather be derivative of the mind itself, by its very composition or nature. This identification of a pre-experiential nature of mind Kant divided into several categories. These were ways the mind worked, fundamental rules it followed for unifying experience. For Kant, these categories include things like cause (and effect, unity, plurality, possibility, etc). This is a transcendental argument, and it shows the impossibility of life as an endless dream - by positing something about reality. In fact, Kant denies Descartes' claim that subjective knowledge is primary. Kant says we need the categories before we can have subjective knowledge.

What is the price of this argument? (We can never see things in themselves) Why? (The categories are our innate filters).

Contemporary debates and virtual reality

Brains in vats (Putnam). What do you think? What do you think of Dennett's attack (inferences in bizzare situations)?

To do for next class

1) Read pp. 21-30 2) Exercise 3 on p.19.

If you have any questions, feel free to email me at

Last updated Oct 98