In the past entry we introduced Plato’s model of the degrees of knowledge, ‘the simile of the line’, according to which the primordial difference between ‘science’ and ‘mere opinion’ is not so much about the ‘methods’ employed to reach one or the other (as will be assumed in modern times), but about the nature of the entities that are ‘known’ in each case: perishable, mutable, imperfect things that are perceived by our senses in the case of ‘opinion’ (dóxa), versus immutable, eternal, and perfect entities directly captured by our intellect in the case of science (epistēmē). We just cannot really know (in the deepest sense of ‘true knowing’) about material things or worldly events, because they are imperfect copies of the essentially and intrinsically ‘knowable’ objects of the true sciences, those that deal with entities that are immaterial and unchanging, entities that populate a separate realm, different from the empirically given natural world. This, as we saw, has an immediate disgraceful consequence: the fact that, according to the Platonic conception, there cannot exist something like a ‘natural science’ properly speaking, for, as we might say, “knowledge of imperfect things is always imperfect knowledge”.
We can conjecture that this unhappy result of Plato’s view of science had its roots in his identification of the notion of ‘science’ with the best developed science of his time (and, actually, the only really ‘developed’ one): mathematics, or geometry more exactly. The Pythagorean theorem, for example, is universally true (‘universally’ in the sense that it is true of all ‘true’ right triangles, and that its truth does not depend on circumstances like location or time… at least in the Euclidean space, we know), perfectly true (the equality it expresses is not ‘approximated’, but absolutely exact), as well as certainly true (there is no possible doubt about whether a right triangle obeys it or not). Its truth, furthermore, is not captured by the senses (we do not learn it by just observing many right triangles, nor by measuring and comparing their sides), but by our intellect or reason, hence it is an intellectual truth; remember that, according to the simile of the line, sense perception can only offer us pístis (“belief”), but not sure knowledge (epistēmē). Plato was convinced that scientific knowledge should always be at least of the kind we have about the Pythagorean theorem, and that everything falling short of that didn’t deserve to be considered ‘scientific enough’. And since some examples of that kind of knowledge were available in his times, why not assume that we had opened the road to the ‘noblest’ kind of knowledge, and that we might discard all that is of ‘inferior’ quality? Mathematical knowledge (and -do not forget it- that kind of science that for Plato was the supreme of all: the ‘dialectical art’ that allowed us to capture the logical relations between all possible ideas) can of course be ‘applied’ to material, concrete, mundane things, but in this case its outcome is always uncertain and debatable: perhaps we have not taken accurate enough measurements, perhaps we have not taken into account important facts, or perhaps someone has deceived us with the data. This is, hence, the reign of sophistry, that we saw exemplified in our second entry, not that of real science.
But let us return to the point that, in my view, is the most important to understand Plato’s cogitations: the fact that the difference between better or worse kinds of knowledge depends basically on the fact that some entities are more perfect than others. This brings us to the important aspect of the simile of the line we did not discuss in the previous entry: the role of ‘the sun’ and ‘the good’. According to Plato, the most characteristic property of the sensible things is… well… that they can be perceived by the senses, and most specifically, that they can be seen. And what is what allows us to see the visible things? Of course, it is light. And what is the ultimate and more powerful source of light? Obviously, it is the sun. Hence, the sun is in some (not totally metaphorical) sense what makes visible things visible, it is the ‘cause of visibility’. Understanding knowledge (even intellectual knowledge) on the model of perception (in the sense that, for Plato, all knowledge reduces to ‘grasp’ something), he assumes that something in the intellectual realm must be playing a role that is analogous to that the sun (or light) plays in the physical realm; i.e., there must be something that is what makes intellectually cognizable things ‘graspable’ by our minds (or ‘rational souls’), something that causes their ‘graspability’ or ‘intelligibility’. (By the way, if you are wondering what conclusion would Plato have reached if, instead of sight, he had taken another sense, like hearing, smell or touch, as its main model of sense perception, you are advancing a very pertinent conundrum, which I will not try to ask here).
Obviously, ‘the Good’ (or the ‘Form’, the ‘Idea’, or the ‘Aspect of the Good’), or more exactly, ‘Goodness itself’, is according to Plato what plays such a role. For, in the same way as visibility is the most characteristic feature of material things, perfection is the most essential aspect of intelligible things, as we have stated above. Hence, what allows our rational minds to understand the intelligible (or ‘understandable’) is the combined fact that they are perfect and that our minds capture the essence of perfection, the knowledge of what perfection is. Geometrical right angles are ‘perfect’, whereas the ones you more or less clumsily draw on paper are not perfect; and in recognizing this difference, you reveal that you have an implicit understanding of the Idea of Perfection itself. Actually, this was probably for Plato his most important ‘philosophical discovery’.
In another of his dialogues, Phaedrus, he depicts Socrates telling that in his youth he was a fan of Anaxagoras’ theory of nature, because he had heard that, contrarily to other ‘naturalist’ pre-Socratic philosophers (or ‘physiologues’, as Aristotle would name it a generation afterwards), the latter attributed the ultimate role in his explanation of Nature to what he called ‘the Noûs’ (Intellect). Unfortunately, once Socrates started examining the details of Anaxagoras’ theory, he found that all his explanations were in the end very ‘mechanical’, like those of most other pre-Socratic (and most explicitly, those of the atomists, like Democritus, that Plato does not even deign to mention), for all natural processes were rationalized by Anaxagoras as mixtures of different natural substances (of which, contrarily to the atomists, or to those defending the theory of ‘four elements’, like Empedocles, he, Anaxagoras, thought were almost infinite in variety); even noûs was conceived in that theory as a kind of fluid impregnating everything! So, nothing really intelligible had any working role in those explanations… what allows us to see that, for Plato, and probably for Socrates before him, ‘intelligibility’ had to be essentially connected to what we now call teleology: the world had to respond to a plan, a conscious, deliberate plan, in order to be truly intelligible. We can understand Plato’s philosophy of science, hence, as the attempt to fulfil that Socratic dissatisfaction, so that his ‘Idea of the Goodness’, as the intuition that the world must have a rational explanation, in the sense that it must somehow be the outcome of a process of reasoning, became the very nucleus of his worldview. Needless to say that this ended having profound, and not always fortunate consequences in the development not only of western philosophy, but of science itself. (By the way, if you are wondering why Plato was driven mad by a physical theory -i.e., a theory about nature, or physis– lacking an explicit role for ‘deliberate goals’, but was very delighted instead with a mathematical theory that was happily unconcerned with any reference at all to something like goals, plans or ends –téloi– in the proofs of its theorems, you are again advancing a very pertinent conundrum, whose answer might have something to do with what I will tell in the next entry).