Is reality intelligible? Can we make sense of it? Or is the world at bottom an unintelligible “brute fact” with no explanation? We can tighten up these questions by distinguishing several senses in which the world might be said to be (or not to be) intelligible. To make these distinctions is to see that the questions are not susceptible of a simple Yes or No answer. There are in fact a number of positions one could take on the question of the world’s intelligibility – though they are by no means all equally plausible.
Consider first the distinction between the world’s being intelligible in itself and its being intelligible to us. Suppose there is, objectively speaking, an explanation of why the world exists in the way it does. Whether we can grasp that explanation is another question. Perhaps our minds are too limited to discover it, or perhaps they are too limited to understand the explanation even if we can discover it.
Might we turn this around and suggest also that the world could be intelligible to us but not intelligible in itself? This proposal seems incoherent. If the world is not intelligible in itself, how could it be intelligible to us? To be sure, we might think that we’ve grasped some explanation even when we haven’t, but that is not the same thing. That would be a case of its merely seeming intelligible to us while not really being intelligible in itself, not a case of its really being intelligible to us while not really being intelligible in itself (whatever that could mean). So we have an asymmetry here: While something could be intelligible in itself but not necessarily intelligible to us, if it really is intelligible to us – and doesn’t just seem to be – then it must also be intelligible in itself.
A second distinction we might draw is that between the world’s being thoroughly intelligible and its being only partially intelligible. This distinction is an obvious one to draw if we think in terms of intelligibility to us. For it might be that the world is intelligible in itself but, while not entirely intelligible to us, at least partially intelligible to us.
Might the world be partially (but not thoroughly) intelligible in itself? Philosophers like Bertrand Russell and J. L. Mackie seem to think so, insofar as they think that we can explain various natural phenomena in terms of the laws discovered by empirical science, but hold also that the most fundamental level of laws cannot itself be explained, and must be regarded as a brute fact. For the reasons given above, however, it would seem incoherent to hold that the world is thoroughly intelligible to us while only partially intelligible in itself. If it is only partially intelligible in itself, it could only ever be partially intelligible to us.
With these distinctions in mind, we might identify the following possible positions on the question of the world’s intelligibility:
A. The world is thoroughly intelligible in itself and thoroughly intelligible to us: We might call this the “strong rationalist” position. Very few philosophers seem ever to have held it, but Parmenides might be an example of someone who did.
B. The world is thoroughly intelligible in itself but only partially intelligible to us: We might call this the “moderate rationalist” position. It was the view of Plato, Aristotle, and Aquinas and seems to have been the position of the continental rationalist philosophers. (The word “rationalism” is, of course, used in many senses. Aristotle and Aquinas were not “rationalists” in the “continental rationalist” sense of being committed to innate ideas.) The continental rationalists were not “strong rationalists” in our sense, insofar as none of them seems to have held that the world is thoroughly intelligible to us. For example, Descartes did not think we could fathom God’s purposes in creating nature as He did; Spinoza thought that we know only two of the infinite attributes of the one infinite substance, viz. thought and extension; and Leibniz did not think our finite monads had the clarity of perception that the infinite monad that is God has.
C. The world is thoroughly intelligible in itself and completely unintelligible to us: It is not clear that anyone has ever actually defended this position. “Mysterian” naturalists like Colin McGinn and Noam Chomsky would not be examples of philosophers taking this position, because while they claim that there might be some aspects of reality that we can never understand, they don’t claim that this is true of every aspect of reality, or even, necessarily, that it is thoroughly the case with respect to any aspect. Their position would seem rather to be a variant on either B above or D below. Nor would the even more skeptical naturalisms of Heraclitus, Hume, or Nietzsche seem to be instances of C. If you’re going to present a theory to the effect that metaphysics is a mere projection of human psychological tendencies, or an expression of a will to power, or whatever, then you are implicitly claiming that at least part of nature (namely us and our tendency toward metaphysical theorizing) is at least partially intelligible. These thinkers too seem committed instead to some variation on either B or D.
D. The world is only partially intelligible in itself and only partially intelligible to us: As indicated above, this seems to be the view of naturalistically-oriented philosophers like Russell and Mackie, who believed that science gives us real knowledge of the world but that the fundamental laws of nature in terms of which it explains all the others are brute facts that cannot themselves ultimately be made intelligible.
E. The world is only partially intelligible in itself and completely unintelligible to us: As with C, it is not clear that anyone has ever actually defended this position.
F. The world is completely unintelligible in itself and completely unintelligible to us: Once again, this does not seem to be a position that anyone has actually ever held. And once again, thinkers who might seem to have held it can be seen on reflection not to have done so. For example, Gautama Buddha might seem to be an example of a thinker committed to F, but he really wasn’t. For even to hold (as the Buddha did) that there is no abiding self or permanent reality of any sort is to make a claim about the world that is intended to be both intelligible and true. And even to recommend (as he also did) against indulging in much metaphysical speculation in the interests of pursuing Enlightenment is to presuppose that there is an objective, intelligible fact of the matter about what would hinder Enlightenment. The Buddha too seems in fact to have been committed to something like a variation on either B or D.
Indeed, it is very difficult to see how one could defend either the view that the world is completely unintelligible in itself or the view that it is completely unintelligible to us. For how could such a view be defended? If you give an argument for the conclusion that reality is unintelligible in itself, it would surely have to rest on premises about reality. You would be saying something like “Reality is such-and-such, and therefore it is unintelligible.” But however you fill in the “such-and-such,” you will be referring to some intelligible feature of reality, or will in any event have to do so if your argument is itself going to be both intelligible and convincing. And in that case you will in effect have conceded that reality is not after all completely unintelligible. By the same token, if you give an argument for the conclusion that reality is unintelligible for us, then you will have to appeal to premises either about some intelligible feature of reality itself, or about our cognitive faculties – which are themselves part of reality – and in that case you will, once again, have implicitly conceded that reality is at least partially intelligible.
So, D would seem to the closest one could come plausibly to claiming that reality is unintelligible. But I think that even D is not really coherent. Suppose I told you that the fact that a certain book has not fallen to the ground is explained by the fact that it is resting on a certain shelf, but that the fact that the shelf itself has not fallen to the ground has no explanation at all but is an unintelligible brute fact. Have I really explained the position of the book? It is hard to see how. For the shelf has in itself no tendency to stay aloft – it is, by hypothesis, just a brute fact that it does so. But if it has no such tendency, it cannot impart such a tendency to the book. The “explanation” the shelf provides in such a case would be completely illusory. (Nor would it help to impute to the book some such tendency after all, if the having of the tendency is itself just an unintelligible brute fact. The illusion will just have been relocated, not eliminated.)
By the same token, it is no good to say “The operation of law of nature C is explained by the operation of law of nature B, and the operation of B by the operation of law of nature A, but the operation of A has no explanation whatsoever and is just an unintelligible brute fact.” The appearance of having “explained” C and B is completely illusory if A is a brute fact, because if there is neither anything about A itself that can explain A’s own operation nor anything beyond A that can explain it, then A has nothing to impart to B or C that could possibly explain their operation. As the Scholastics would say, a cause cannot give what it does not itself have in the first place. A series of ever more fundamental “laws of nature” is in this regard like a series of instrumental causes ordered per se. The notion of “an explanatory nomological regress terminating in a brute fact” is, when carefully examined, as incoherent the notion of “a causal series ordered per se in which every cause is purely instrumental.” And thus Mackie’s and Russell’s position is itself ultimately incoherent.
The only truly coherent positions one could take on the question of the world’s intelligibility, then, are A and B. And A is, needless to say, not very plausible, even if coherent. So, some variation on B seems to be the most plausible view to take on the world’s intelligibility. Why do people bother with D, then? The answer is, I think, obvious. It is very hard to affirm either A or B without committing oneself either to classical theism or pantheism. For once it is conceded that the world is at least in itself completely intelligible, it is hard to see how this could be so unless the most fundamental level of reality is something absolutely necessary – something that is not a mixture of potentiality and actuality but rather pure actuality (as the Aristotelian would say), something which is in no way whatsoever composite but absolutely metaphysically simple (as the Neo-Platonist would say), something which is not a compound of essence and existence but rather subsistent being itself (as the Thomist would say). However one elaborates on the nature of this ultimate reality, it is not going to be identifiable with any “fundamental laws of nature” (which are contingent, and the operation of which involves the transition from potentiality to actuality within a universe of things that are in various ways composite). One might still at this point dispute whether the ultimate reality is best described in terms of the theology of classical theism or instead in terms of some pantheistic theology. But one will definitely be in the realm of theology – rational theology, natural theology – rather than empirical science.
If one wants to maintain a defensible atheist position, then, one has to try to make something like D work, as Russell and Mackie (and my younger self) did. One has to claim with a straight face that the world is intelligible down to the level of the fundamental laws, but beyond that point suddenly “stops making sense” (as Talking Heads might put it). For one has to say, not that the world has some ultimate explanation that is non-theistic, but rather that it has no ultimate explanation at all. And in that case one can hardly claim to have provided a more “rational” account of the world than theism does. To paraphrase what Copleston said to Russell, if you refuse to play the explanatory game, then naturally you cannot lose it. But by the same token, it is ludicrous to claim that you’ve won it.