Microsoft Word - Tripartite theory of knowledge.docx

Michael Lacewing The tripartite definition of knowledge What is knowledge? In this handout, we discuss the claim, deriving from Platos dialogue Theaetetus, that knowledge is a belief that is both true and justified. This claim was widely accepted until 1963, when Edmund Gettier published a very strong objection. Types of knowledge First, we need to clarify some terminology. There are different types of knowledge. The first is acquaintance knowledge. This is knowledge of someone or some place. For example, I know Oxford well. The second is ability knowledge, knowing how to do something. For example, I know how to ride a bike. These first two types of knowledge are very interesting, and raise some important philosophical puzzles, but we will be concerned only with a third type of knowledge, propositional knowledge. Propositional knowledge is knowledge that some claim a proposition is true or false. A proposition is a declarative statement, or more accurately, what is expressed by a declarative statement, e.g. eagles are birds. Propositions can go after the phrases I believe that and I know that. So I know that eagles are birds. From now on, our question is, what is it to know that a proposition is true or false? The tripartite definition of knowledge The tripartite definition of knowledge claims that knowledge is justified, true belief. It claims that if you know some proposition, p, then the proposition p is true; you believe that p; your belief that p is justified.

And if you have a justified true belief that p, then you know that p. Necessary and sufficient conditions The tripartite definition aims to provide a complete analysis of the concept of propositional knowledge. Its three conditions, taken together, are intended to be equivalent to knowledge. So if someone knows some proposition, they should fulfil exactly those three conditions. And if they fulfil those conditions, then they know the proposition. The conditions are necessary and sufficient conditions for their knowledge that p. Necessary and sufficient conditions are related to conditional statements, which take the form if x, then y. Such statements relate the truth of two propositions, e.g. it is raining and I am getting wet, e.g. If it is raining, then I am getting wet. The conditional asserts that if the first statement (known as the antecedent) is true, then the second statement (the consequent) is also true. Suppose the conditional is true: if it is raining, then I am getting wet. It follows that if the antecedent is true (it is raining), then the consequent is true (Im getting wet). It also follows that if the consequent is false (I am not getting wet), then the antecedent is false (it is not raining). The tripartite definition of knowledge claims that if all the three conditions it lists are satisfied if you have a justified true belief that p then you know that p. You dont need anything else for knowledge; the three conditions, together, are sufficient. It also says that if you know that p, then you have a justified true belief that p. There is no other way to know that p, no other analysis of knowledge. So, it claims, each of the three conditions is necessary. If p is false, or you dont believe that p, or your belief that p is not justified, then you dont know that p. So the definition puts forward two conditionals: if all three conditions are satisfied, then you know that p; and if you know that p, then all three conditions are satisfied. This means whenever you have one, you have the other. Knowledge and justified true belief are the same thing. Justified true belief is necessary for knowledge (you cant have knowledge without it), but it is also sufficient for knowledge (you dont need anything else). Are the conditions individually necessary? We can raise two kinds of objection to the tripartite definition of knowledge by searching for counterexamples. The method of finding counterexamples is important in philosophy. If a theory makes a general claim, such as all propositional knowledge is justified true belief, we only need to find a single instance in which this is false to show that something is wrong with the theory. (Of course, we then have to find out what is wrong with it.) First, it may be that one of the conditions is not necessary for knowledge can we have knowledge without justified true belief? Second, it may be that all of the conditions together are still not sufficient for knowledge can we have justified true belief without knowledge? We will discuss the first question in this handout, leaving the second question for a separate handout on Gettiers objection and responses to it. Justification is not a necessary condition of knowledge Why think that justification is necessary for knowledge? Could knowledge be just true belief? The difficulty with this suggestion is that people can have true beliefs without having any evidence or justification for their beliefs. True beliefs can be formed or held on irrational grounds. For example, someone on a jury might think that the person on trial is guilty just from the way they dress. Their belief, that the person is guilty, might be true; but how someone dresses isnt evidence for whether they are a criminal! Or again true beliefs can just be lucky. For example, there is a lot of evidence that astrology does not make accurate predictions, and my horoscope has often been wrong. Suppose on one occasion, I read my horoscope and believe a prediction, although I know there is evidence against thinking it is right. And then this prediction turns out true! Did I know it was right? In both examples, it is counter-intuitive to say that the belief counts as knowledge, because the person has no reason, no evidence, no justification, for their belief. Knowledge, then, needs some kind of support, some reason for thinking that the proposition believed is true. This is what is meant by saying that knowledge needs to be justified. (Some philosophers have thought that another difference between knowledge and belief is certainty. Knowledge must be certain; beliefs dont have to be. If a belief is certain, then it cant count as knowledge.) We can object that sometimes we use the word know just to mean believe truly, without worrying about justification. If I ask, Do you know who wrote the Meditations?, Im only interested in whether you have the true belief that it was Descartes. But we could reply that this is just a loose use of the word know; strictly speaking, unless your belief is justified, it isnt really knowledge. Alternatively, we could say that true belief can count as knowledge (at least sometimes) in this sense; but there is another, stronger sense of knowledge, which is what we are interested in here. Truth is not a necessary condition of knowledge Could knowledge be simply justified belief? There are two very different possibilities here. First, perhaps we can know what is false. Second, perhaps we shouldnt talk about truth or falsehood at all. People can believe propositions that arent true. For example, someone may claim that flamingos are grey, and think that they know this. But they are mistaken: flamingos are not grey, but pink. Of course, they believe that flamingos are grey, they may even be certain that flamingos are grey. But beliefs can be false, and if they are, then they are not knowledge. You cant know something false. What if many people, perhaps a whole society, share a particular belief and have good reasons for doing so? For instance, almost everybody used to believe that the Earth is flat. It does, after all, look that way. Should we say that people used to know that the Earth is flat? Or should we say that they didnt know it, they only believed it? Another puzzle arises with how specific we make the claim. One of the most important revolutions in scientific thinking was the shift from Newtonian physics to Einsteins theory of relativity. Now, our everyday experience is very accurately described by Newtonian physics (because we are not moving at speeds close to the speed of light). However, strictly speaking, Newtonian physics is false. So do we know the claims of Newtonian physics, which after all, we rely on and use all the time, very successfully? One response is to note that the claims of Newtonian physics are roughly true, or true enough in the context of everyday life. So rather than saying we dont know them, because strictly speaking they are false, we can say that we do know them, roughly speaking. This response rules out the opposite claim regarding the flat Earth it is not even roughly true that the Earth is flat, so people only believed, but didnt know, that it was flat. Doing away with truth? Thomas Kuhn argues that science repeatedly involves large shifts in thought, such as the shift from Newtonian to Einsteinian physics (The Structure of Scientific Revolutions). One way of thinking, which Kuhn calls a paradigm, is replaced by another. When this happens, Kuhn claims, we cant compare the two paradigms in such a way as to say that one is true and the other is false, because paradigm shifts involve changes in the concepts that we use to understand and explain reality. And there is not just one right set of concepts that matches reality. It is natural to think that a scientific theory (paradigm) can be evaluated as true or false, or at least better (more true) or worse (more false), by comparing its claims with evidence derived from observation. But, argues Kuhn, there is no theory-neutral way of describing the world which we can use to compare and judge between two paradigms. How scientists describe what they observe depends on the concepts they use. The main concepts of a paradigm acquire their meaning in relation to the paradigm as a whole. Therefore, a different paradigm, even if it uses the same term, interprets the concept differently, because it plays a new and different role. Therefore, different paradigms are talking about different things. There is no neutral way of describing the world. Therefore, we cannot compare different paradigms claims to say that one is more correct or true than another, as they could both be correct in their own terms.

If we insist that knowledge involves truth, then it will be difficult to talk of scientific knowledge. So we should say that knowledge is justified belief. We can object that if we do not assume that scientific theories are getting closer to the (objective) truth, we cannot explain the success of science. Technology has advanced considerably the best explanation for this is that the scientific theories which underpin technology are more accurate than before. Kuhn responds that there is progress, including the solving of problems, but he argues that the idea that we are getting closer to the truth makes no sense. Science responds to the challenges it faces at any particular time; this does not mean that there is an ultimate goal truth towards which it is moving. A different objection is to argue that there have been no revolutions as Kuhn describes them. Changes in scientific theory involve considerable continuity and overlap, e.g. in beliefs about methodology and evidence. If there have been no Kuhnian revolutions, then scientific theories exhibit enough similarity for us to compare them and judge which is better. A third objection accepts that we cant talk about Truth (with a capital T), how the world really is independent of our concepts or experience or way of thinking about it. But we can still argue that within each way of thinking, there are true (small t) and false beliefs. And only those beliefs that are true, using the concepts available within that paradigm, can count as knowledge. Knowledge is not justified True belief, it is justified true belief. Belief is not a necessary condition of knowledge There are two strengths of the objection that belief is not necessary for knowledge. The weak objection is that sometimes it is possible to know something without believing it. The strong objection is that knowledge is never a form of belief. The weak objection: suppose John is sitting an exam, but hes very nervous and has no confidence in his answers. Suppose when answering Which philosopher wrote the Meditations?, he writes Descartes. Hes right, and the answer isnt a lucky guess he has remembered what he learned. So it is plausible to say that John knows the answer, he knows more than he thinks hes just unconfident. But because hes unconfident, we should say that John doesnt believe that the answer is Descartes. So he knows the answer without believing it. We can defend the tripartite definition by replying in one of two ways. We can say that John doesnt know the answer, e.g. because he cant produce a justification for giving that answer. Or we can say that John does believe that the answer is Descartes, although this belief is unconscious or tacit. This unconscious belief amounts to knowledge. Knowledge is not a form of belief Timothy Williamson argues that knowledge is not a form of belief, but an entirely different mental state (Knowledge and Its Limits). Either you believe something or you know it; but you dont know something by believing it. We can understand this by comparing knowledge and perception. We only see that the tea is on the table if the tea is on the table. If we hallucinate this, that is an entirely different kind of mental state. Perception is not hallucination + added conditions (e.g. that what appears to you is how things are). Perception is a factive mental state you can only be in a perceptual state, such as seeing something, if the world is the way you perceive it to be. Knowledge is the same. You can only know that p if p is true. Belief, by contrast, is a mental state that can be true or false you can have a belief that p whatever the world is like. Knowledge is factive, belief is not. The tripartite definition explains this difference by saying that knowledge is belief with additional conditions (truth, justification). But every attempt to spell out the conditions has met objections. This is a reason to think that knowledge is not a kind of belief at all. Knowledge is unanalysable there are no necessary and sufficient conditions that accurately describe what knowledge is. (If some analysis of knowledge is convincing, this theory loses much of its motivation.) Williamson argues that knowledge is the most general factive mental state. What this means is that any factive mental state is a way of knowing. So seeing is factive a way of knowing something is to see that it is the case. Another example is remembering. You dont remember something if what you think you remember is not actually true. So remembering is a way of knowing (about the past). And so on with other factive states. Williamson argues that we should understand belief in terms of knowledge. To believe that p is to take p to be true. You cant believe that elephants are grey while also believing that your belief that elephants are grey is false! Put another way: to believe that p is to treat p as if you know that p. We can only understand what beliefs are if we first understand what knowledge is. One objection to Williamsons theory points to those occasions on which we make mistakes. Suppose I think I know something, but it turns out I didnt. We would usually say that I had, nevertheless, believed it. I believed it, but I thought I knew it; this shows that we can mistake belief for knowledge. If knowledge isnt a kind of belief, this would be puzzling. But Williamson can reply that just because belief and knowledge can be subjectively indistinguishable does not tell us anything significant about what knowledge is.