Rand once claimed that, “ Nothing is self-evident except the material of sensory perception.” However, the Objectivist “axioms” are also regarded as self-evident, even though it is not clear in what sense these axioms can be regarded as “material of sensory perception” (or even what “material of sensory perception” is supposed to mean!). In dealing with the Objectivist metaphysics, “we must speak by the card, or equivocation will undo us.”
David Kelley defined an axiom as “a self-evident principle that is implicit in all knowledge.” How is an axiom “self-evident”? What does this self-evidence rest on? Objectivists resort to a rather strained argument that convinces only those who wish to be convinced. “An axiom is a proposition that defeats its opponents by the fact that they have to accept it and use it in the process of any attempt to deny it,” explained Rand [emphasis added]. In other words, according to Rand, an axiom is true and self-evident because you cannot refute it without assuming its validity. However, is this notion of how an axiom is true and self-evident also self-evident? And if it is not, how can Rand claim that her axioms are self-evident?
Here’s one problem: Rand claims that every one of her axioms are assumed in the attempt to deny them. How does she know this? Is she familiar with all the potential arguments that can be essayed against them? Of course not: she can’t be familiar with every attempt to deny them. Therefore her assertion is based on a kind of inference—namely, an inductive inference. Now whatever Rand or anyone else thinks of induction, such inferences can hardly be reckoned as self-evident. Therefore, her very belief that her axioms can only be denied by assuming them does not carry with it the stamp of self-evidence, which her axioms require to pass muster.
There’s another problem as well. It seems that Rand did not really understand extreme skepticism, that she may very well have been guilty of confusing the necessary presuppositions of her own philosophy with those of the skeptic. As Santayana noted,
The sceptic is not committed to the implications of other men’s language; nor can he be convicted out of his own mouth by the names he is obliged to bestow on the details of his momentary vision. There may be long vistas in it ; there may be many figures of men and beasts, many legends and apocalypses depicted on his canvas ; there may even be a shadowy frame about it, or the suggestion of a gigantic ghostly some thing on the hither side of it which he may call himself. All this wealth of objects is not inconsistent with solipsism, although the implication of the conventional terms in which those objects are described may render it difficult for the solipsist always to remember his solitude. Yet when he reflects, he perceives it; and all his heroic efforts are concentrated on not asserting and not implying anything, but simply noticing what he finds. Scepticism is not concerned to abolish ideas ; it can relish the variety and order of a pictured world, or of any number of them in succession, without any of the qualms and exclusions proper to dogmatism. Its case is simply not to credit these ideas, not to posit any of these fancied worlds, nor this ghostly mind imagined as viewing them. [Scepticism and Animal Faith, 15-16]
In short, Rand seems to have forgotten that denying existence means denying that the images of sense relate to an external, substantive world of fact, existing in time and space. Positing a world from the data of sense can never be “self-evident.” The only thing that is “evident” to the self is the passing rush of datum across the mind’s sentience. Yet none of these datum, taken by themselves, can be evidence of anything until we assume they are signs of outward things existing in reality. And that assumption, although true, is hardly “self-evident.”