Plato views about knowledge

Plato proved that, Knowledge is constructed out of perception and perception alone “empiricism”. Plato's purpose is to salvage as much as possible of the theories of Protagoras and Heracleitus. Plato's strategy is to show that these theories have their own distinctive area of application, the perceptible or sensible world, within which they are true. However, the sensible world is not the whole world and so these theories are not the whole truth. We get absurdities if we try to take them as unrestrictedly true. To avoid these absurdities it is necessary to posit the intelligible world (the world of the Forms) alongside the sensible world (the world of perception). When this is done, Platonism subsumes the theories of Protagoras and Heracleitus as partial truths. On this reading, the strategy of the discussion of the first assumption is to transcend Protagoras and Heracleitus so as to explain their views by showing how they are, not the truth, but parts of a larger truth. In the process the discussion reveals logical pressures that may push us towards the two-worlds Platonism that many readers such as Ross and Cornford, find in the Republic and Timaeus.

On the Revisionist reading, Plato's purpose is to refute the theories of Protagoras and Heracleitus. He thinks that the absurdities those theories give rise to, he came not from trying to take the theories as unrestrictedly true, but from trying to take them as true at all even of the sensible world. Anyone who tries to take seriously the thesis that knowledge is perception has to adopt theories of knowledge and perception like Protagoras' and Heracleitus'. But their theories are untenable. By modus tollens this shows that first assumption itself is untenable. On this, the strategy of the discussion of first assumption is to move us towards the view that sensible phenomena have to fall under the same general metaphysical theory as intelligible phenomena. Plato made three assumptions when he trying to prove his argument;

Firstly, knowledge could be simply identified with perception where by Knowledge is nothing other than perception. Plato's strategy in the critique of the first assumption highlights two distinctions:

·         A distinction between the claim that the objects of perception are in flux, and the claim that everything is in flux.

·          A distinction between bare sensory awareness, and judgment on the basis of such awareness. Perceptions alone have no semantic structure. So if this thesis was true, it would be impossible to state it.

Certainly it is easy to see counter-examples to the alleged entailment. Take for instance the thesis that knowledge is awareness or take the thesis that to know is to perceive things as God or the ideal observer, perceives them and that we fail to know (or to perceive) just insofar as our opinions are other than God's or the ideal observer's. These theses are both versions of first assumption. Neither entails him, the claim that “man is the measure of all things” nor the Protagoreanism that lies behind that slogan.So how, if at all does first assumption entail all the things that Socrates apparently makes? And does Plato think it has all these entailments? Evidently the answer to that depends on how we understand the first assumption. In particular way, it depends on the meaning of the word aesthesis, “perception” in first assumption. If the slogan “Knowledge is perception” equates knowledge with what ordinary speakers of classical Greek would have meant by aesthesis, then first assumption does not entail Protagoras' and Heracleitus' views. In the ordinary sense of aesthesis, there are (as just pointed out) too many other possible ways of spelling out the first assumption for the move to him to be logically obligatory. But if the slogan “Knowledge is perception” equates knowledge with what Protagoras and Heracleitus meant by aesthesis, first assumption does entail Protagoras' and Heracleitus' views. Of course it does, for then first assumption simply says that knowledge is just what Protagoras and Heracleitus say knowledge is.

Secondly, knowledge can be defined as true belief, where beliefs are supposed to be semantically-structured concatenations of sensory impressions. Against this Plato argues that, unless something can be said to explain how impressions can be concatenated so as to give them semantic structure, there is no reason to grant that the distinction between true and false applies to such beliefs any more than it does to perceptions. Perception seems to mean “immediate sensory awareness” at other times it seems to mean “judgments made about immediate sensory awareness”. The proposal that “Knowledge is immediate sensory awareness” is rejected as incoherent, “Knowledge is not to be found in our bodily experiences, but in our reasoning about those experiences”. The proposal that “Knowledge is judgment about immediate sensory awareness” raises the question how judgments, or beliefs, can emerge from immediate sensory awareness. Empiricists claim that sensation, which in itself has no cognitive content, is the source of all beliefs, which essentially have cognitive content—which are by their very nature candidates for truth or falsity. So unless we can explain how beliefs can be true or false, we cannot explain how there can be beliefs at all. Hence Plato's interest in the question of false belief. What Plato wants to show, is that there is no way for the empiricist to construct contently belief from contentless sensory awareness alone. The corollary is that we need something else besides sensory awareness to explain belief. In modern terms, we need irreducible semantic properties. In Plato's terms, we need the Forms.

The first proposal about how to explain the possibility of false belief is the proposal that false belief occurs when someone misidentifies one thing as another. To believe or judge falsely is to judge for some two objects that first object equal to the second object. How can such confusions even occur? Plato presents a dilemma that seems to show that they can't. The objects of the judgement, first object and second object must either be known or unknown to the judger x. Suppose one of the objects, first object is unknown to x. In that case, first object cannot figure in x's a thought at all since x can only form judgements using objects that he knows. So if first object is not an object known to x then x cannot make any judgement about first object. Then x can make no false judgement about first object either.

Finally, he made an attempt to meet this challenge, and present some explanation of how semantic structures can arise out of mere perceptions or impressions. The proposed explanation is the Dream Theory, a theory interestingly comparable to Russellian Logical Atomism, which takes both propositions and objects to be complexes “logically constructed” out of simple sensory impressions. On this conception, knowledge will come about when someone is capable not only of using such logical constructions in thought, but of understanding how they arise from perception.

If what Plato wants to tell us is that he no longer accepts any version of third assumption, not even his own version, then it is extraordinary that he does not even mention his own version, concentrating instead on versions of third assumption so different from Plato's version as to be obviously irrelevant to its refutation. Indeed, Plato's strategy is to refute what he takes to be false versions of third assumption so as to increase the logical pressure on anyone who rejects Plato's version of third assumption. In particular way, he wants to put pressure on the empiricist theories of knowledge that seem to be the main target. What Plato wants to show is not only that no definition of knowledge except his own but also third assumption is acceptable, but also that no version of third assumption except his own is acceptable.

Therefore, the fundamental problem for empiricism as we saw is how to get from sensation to the content or in other way we can say that the problem of how we could start with bare sense-data, and build up out of them anything that deserved to be called meaning. Plato thinks that there is a good answer to this though it is not an empiricist answer. Sense experience becomes contentful when it is understood and arranged according to the structures that the Forms give it. So to understand sense experience is in the truest sense “to give an account” for it.

The empiricist cannot offer this answer to the problem of how to get from sensation to content without ceasing to be an empiricist. What the empiricist can do is propose that content arises out of sets of sense experiences. We get to the level of belief and knowledge only when we start to consider such sets before that we are at the level only of perception. Our beliefs couched in expressions that refer to and quantify over such sets, will then become knowledge;

        i.            When they are true.

      ii.            When we understand the full story of their composition out of such sets.

To differentiate knowledge of an object from true belief about such object, then what it adds is a diagnostic quality of that object. If there is a problem about how to identify an object then there is a problem about how to identify the diagnostic quality too. This launches a vicious regress.

One way of preventing this regress is to argue that the regress is caused by the attempt to work up a definition of knowledge exclusively out of empiricist materials. Hence there is no way of avoiding such a vicious regress if you are determined to try to define knowledge on an exclusively empiricist basis. The right response is to abandon that attempt. Knowledge is indeed indefinable in empiricist terms. In those terms, it has no logos. In those terms, therefore, knowledge itself is unknowable. For this reason, we still do not know how to define knowledge even on the most skeptical reading; this does not mean that we have not learned anything about what knowledge is like. And as many interpreters have seen, there may be much more to the ending than that. No true beliefs alone can even begin to look like they might count as knowledge. Perhaps it is only when we, the readers, understand this point (which epistemological success in the last resort depends on having epistemological virtue-that we begin not only to have true beliefs about what knowledge is, but to understand knowledge).