Philosophers do not agree about anything to speak of. And why not? How can it be that equally intelligent and well-trained philosophers can disagree about the freedom of the will or nominalism or the covering-law model of scientific explanation when each is aware of all the arguments and distinctions and other relevant considerations that the others are aware of? How can we philosophers possibly regard ourselves as justified in believing anything of philosophical significance under these conditions? How can I believe (as I do) that free will is incompatible with determinism or that unrealized possibilities are not physical objects or that human beings are not four-dimensional things extended in time as well as in space when David Lewis—a philosopher of truly formidable intelligence and insight and ability—rejects these things I believe and is aware of and understands perfectly every argument that I could bring in their defense?
Peter van Inwagen, ‘Quam dilecta’, in Thomas V. Morris (ed.), God and the Philosophers: The Reconciliation of Faith and Reason, New York, 1994, pp. 40-41
Let us suppose, unrealistically, that IQ tests really measure intellectual ability. Let us in fact assume, even more unrealistically, that they measure the intellectual abilities that are relevant to success in metaphysics. Why should we suppose that a species with a mean IQ of 100—our own species—is able to solve the problems of metaphysics? Pretty clearly a species with a mean IQ of 60 wouldn’t be in a position to achieve this. Pretty clearly, a species with a mean IQ of 160 would be in a better position than we to achieve this. Why should we suppose that the “cut-off-point” is something like 90 or 95? Why shouldn’t it be 130 or 170 or 250? The conclusion of this meditation on mystery is that if metaphysics does indeed present us with mysteries that we are incapable of penetrating, this fact is not itself mysterious. It is just what we should expect, given that we are convinced that beings only slightly less intellectually capable than ourselves would certainly be incapable of penetrating these mysteries. If we cannot know why there is anything at all, or why there should be rational beings, or how thought and feeling are possible, or how our conviction that we have free will could possibly be true, why should that astonish us? What reason have we, what reason could we possibly have, for thinking that our intellectual abilities are equal to the task of answering these questions?
Peter van Inwagen, Metaphysics, Boulder, Colorado, 1993, p. 201
Suppose that we were to divide a square into a million smaller squares by dividing each of its sides into a thousand equal parts. And suppose that we took the first million digits in the decimal part of pi and interpreted each as corresponding to one of the million squares by some simple correspondence rule (something like this: the top left square is assigned the first digit, the next square to the right is assigned the second digit, and so on). And suppose that we assigned a color to each of the numbers 0 through 0 and painted each of the small squares with the color corresponding to the number assigned to it.
What would we say if the result turned out to be a meaningful picture—a landscape or a still life or something equally representational—of surpassing beauty?
Peter van Inwagen, Metaphysics, Boulder, Colorado, 1993, p. 137