In the Theaetetus, Plato investigates the nature of knowledge. The interlocutors of this dialogue are Socrates and two mathematicians – Theaetetus and Theodorus. Theaetetus tells Socrates that the various arts and sciences – geometry, astronomy, the art of cobbling, etc. – constitute knowledge. Socrates refutes Theaetetus’ argument by demonstrating that Theaetetus has merely provided examples of knowledge. If Socrates asked, “What is color?” and Theaetetus replied, “Color is red, blue, orange, etc.” his answer is clearly inadequate. Socrates seeks a precise definition of what these various types of knowledge have in common.
Theaetetus expresses his difficulty in forming a definition of knowledge. Socrates explains that Theaetetus is experiencing discomfort because Socrates is helping him give birth to an idea. Socrates claims to be a sort of midwife for the soul. This metaphor reminds me of the assertion made by Cicero (or some other philosopher, hopefully someone can provide me with the correct author’s name in the comment section) that births of the soul are more valuable than births of the body. Thus, friendship is better than sexual love because friendship cultivates noble creations of the soul, while the other passion merely produces children.
Next, Theaetetus proposes that knowledge is perception. Socrates restates Theaetetus’ definition using a doctrine of Protagoras – “man is the measure of all things.” In other words, if a wind appears cold to a man, then the wind is cold for that man. Socrates’ first objection is that if every is a measure for truth, then no man can be wiser than another. The followers of Protagoras would respond that some are wiser than others because they enable others to perceive “better.” These wise men teach others to perceive sorrowful events as occasions for happiness.
Socrates then argues that the doctrine of Protagoras is self-refuting. For example, many people believe that there are false opinions. If all opinions are true according to Protagoras’ doctrine, then there are false opinions. If not all opinions are true, then there are false opinions. Either way, there are false opinions, which refutes the doctrine of Protagoras. Another form of this argument of self-refutation runs thus: Protagoras asserts that all opinions are true. His opponents do not believe that all opinions are true. Protagoras accepts their disbelief as true, which renders him a disbeliever in his own doctrine. The contradiction is plain.
Finally, Socrates argues that some knowledge is not derived from perception, but rather solely from the soul/reason. Mathematical concepts are instances of knowledge attained independent of perception.
The third definition of knowledge that Theaetetus proposes is that knowledge is true belief. Socrates rejects this definition with a courtroom analogy. He asserts that a jury which is persuaded that a man is guilty does not know that the man is guilty – though the man may very well be so – but rather they are merely persuaded to hold a particular opinion. If that opinion accords with truth, then it is fortuitous, but this type of opinion clearly does not constitute knowledge.
Finally, Theaetetus proposes that knowledge is true belief with an account. To give an account of something may mean to enumerate the elements of a complex thing or identify the characteristics which distinguish a thing from all others. Socrates rejects this reasoning as begging the question because it essentially defines knowledge as a true account with knowledge of distinguishing characteristics.
The dialogue ends in aporia – a state of doubt – as to the nature of knowledge. However, like all Socratic dialogues, the interlocutors and the reader at least know what the subject of the dialogue is not. To summarize, knowledge is not the sciences, arts, perception, true belief, or true belief with an account. Plato’s dialectical writing style is worthy of emulation. Philosophy can be insipid at times, especially when reading bland authors like Kant, but writers such as Plato who add dramatic elements to the text can pique a reader’s interest and thus render the material easier to comprehend and retain.
“Human nature cannot know the mystery of an art without experience.”
“You cannot rightly call anything by any name, such as great or small, heavy or light, for the great will be small and the heavy light-there is no single thing or quality, but out of motion and change and admixture all things are becoming relatively to one another, which “becoming” is by us incorrectly called being, but is really becoming, for nothing ever is, but all things are becoming.”
“Wonder is the feeling of a philosopher. Philosophy begins in wonder.”
“As our time is equally divided between sleeping and waking, in either sphere of existence the soul contends that the thoughts which are present to our minds at the time are true; and during one half of our lives we affirm the truth of the one, and, during the other half, of the other; and are equally confident of both.”
“Is truth or falsehood to be determined by duration of time?”