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Ryerson University
PHL 550
Christopher Gore

Plato defines knowledge as justified belief and if this belief is true, then it can be justified by some facts or evidence. The JTB theory of knowledge attempts to offer a set of sufficient and necessary conditions wherein an individual can be believed to know something.According to the JTB theory of knowledge, is an individual S has a belief P, if P is in fact true, and if S is justified in believing P, then S knows that P. (Chrucky) I believe, for example, that I have two eyes, I actually do have two eyes, and I can justify my belief in having two eyes because I’m making use of my eyes to watch while I am writing. This means that according to JTB theory of knowledge, I know that I’ve two eyes. There are three conditions to the JTB theory of knowledge, which make this theory justified, true and sufficient for knowledge. The JTB theory of knowledge states that S knows that P if (i) P is true, (ii) S believes that P, and (iii) S is justified in believing that P. The JTB theory of knowledge was challenged by Edmund Gettier who questioned whether knowledge is the true belief that is justified. Gettier devised two counterexamples in order to illustrate that knowledge cannot be effectively defined as justified true belief. Gettier came up with two cases in which the subject intuitively achieves a justified true belief that doesn’t prove that it’s knowledge. His counterexamples provide a situation wherein a person has a belief which is true and it has evidence as well, but it is still not knowledge. Gettier’s counterexamples have resulted in a re-evaluation of the JTB theory.Alot of attempts have been made to modify the JTB theory in order to account for Gettier’s counterexamples such that they’ll not be defined as knowledge. (BonJour 2000) I think the JTB Theory of knowledge could be modified by adding an additional necessary and sufficient fourth condition to the theory, which could be “S has sufficient evidence that P.” 2 The traditional view of knowledge is justified true belief. Plato’s dialogue Theaetetus, defined knowledge as justified true belief. A leading epistemology textbook states knowledge as, “It is reasonable to say [that] some version or other of the traditional conception of knowledge was taken for granted by virtually all philosophers seriously concerned with knowledge in the period from the time of Descartes until the middle of the twentieth century.” (BonJour 2001: 43) This view about knowledge was accepted until Edmund L. Gettier, challenged Plato’s view in an article: Is Justified True Belief Knowledge? Gettier came up with two counterexamples to challenge the standard view about knowledge that strictly held the three JTB conditions for knowledge. JTB theory of knowledge has three conditions, namely the truth condition, the belief condition and the justification condition. The first condition (p is true) is uncontroversial as a lot of epistemologists think it is true that if something is false, it cannot be known. Truth is essential for knowledge and according to the truth condition; a person cannot know that a claim is true if it is actually false. For example, if our planet isn’t flat, then I don’t know that the earth is flat. I don’t think that anyone would have an objection to the truth condition. The second condition is that S believes p, and is hence known as the belief condition. This condition is also widely accepted, however this condition is controversial compared to the truth condition. Belief condition can be challenged on the grounds that believing and knowing are not compatible (Plato, Duncan-Jones 1938). But I think that knowing not only involves believing but it should be backed up by something like sufficient or adequate evidence. This is why these two conditions cannot be considered necessary and sufficient for knowledge. And this is where the justification condition comes in, according to which, S is justified in believing that p. A person must have substantial ground for believing p. For example, if someone predicts the existence of 3 animals based on a coin toss, then that person could have grounds for believing their actions. But these grounds are poor and untrustworthy to be considered for knowledge. For someone to have knowledge, it is very important that their belief is in some epistemic sense appropriate or proper: and it should be justified. (Bird: 81–110) The JTB theory of knowledge was accepted by many until after Edmund Gettier questioned if knowledge is the true belief that is justified. Gettier came up with counterexamples in order to illustrate that knowledge cannot be effectively defined as justified true belief.According to Gettier, his counterexamples showed that a justified true belief was not sufficient for knowledge. Gettier’s counterexamples are aimed at proving that knowledge is not equal to justified true belief. This is why the Gettier problem should be solved in order to effectively define knowledge. Here is a Gettier example where a particular individual’s belief that p is justified (or appears to be justified), but does not represent a genuine case of knowing that p: Jenny sees a person walking down the streets who appears like her brother Mike. She sees that a man who is just like her brother is coming towards her house and just by that, she concludes that her brother Mike is coming over to her house. When
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