I am reading "Ancient Philosophy" by Anthony Kenny (Vol 1 of his "A New History of Western Philosophy", OUP, ISBN 0–19–875273–3).
I was intrigued by the following statement (p.176):
"However, ancient epistemology is bedevilled by two different but related fallacies. Both of them are generated by a misunderstanding of the truth that whatever is knowledge must be true. One of the fallacies haunts classical epistemology, up to the time of Aristotle; the other fallacy haunts Hellenistic and imperial epistemology."
For the sake of limiting the scope of discussion, my question is about the first fallacy. Here's how Kenny describes it:
"The first fallacy is this. ‘Whatever is knowledge must be true’ may be interpreted in two ways.
(1) Necessarily, if p is known, p is true or
(2) If p is known, p is necessarily true.
(1) is true but (2) is false. It is a necessary truth that if I know you are sitting down, then you are sitting down; but if I know you are sitting down it is not a necessary truth that you are sitting down; you may get up at any moment. Plato and Aristotle, over and over again, seem to regard (2) as indistinguishable from (1). Given the necessary connection between knowledge and truth, they seem to think, only what is necessary can be known. From the acceptance of (2) there flows the construction of the theory of eternal and immutable Ideas, and there flows the impossible ideal of Aristotelian science." (p.176-177)
My question is, what exactly is Kenny saying about Plato's and Aristotle's epistemological views?
I mean, it seems that he's talking about contigent vs. necessary truth, and that Plato & Aristotle thought of all truth as necessary -- but I don't understand what that really means in terms of their theories. Is it being claimed that if Aristotle saw a blue unicorn, he'd assert that all unicorns are necessarily blue? I.e. that he would not be able to conceive of (the truth of) the color as being contingent on the particular unicorn? Or is it being claimed that he'd consider the blue-ness of a specific unicorn to be something less than truth, precisely because this blue-ness is not necessary of other unicorns? Or something else?
Kenny closes by making a strong claim about the "impossible ideal of Aristotelean science". I think here he ascribes to Aristotle the theory that science should be a deductive (via syllogisms) process, producing only "necessary" truths. But is calling it an "impossible ideal" really justified, especially in the sense of Aristotle committing some kind of clear fallacy..? After all, didn't the logical positivists take up exactly this line of thinking about truth, and haven't they come up with some interesting/useful/influential arguments about what science is, even if other approaches have become more popular..?