The Limits of Reason

Our brains have limits on what they can think and what tools they can bring to thinking.

One feature of human nature and experience that strikes me as entirely obvious, but turns out to be surprisingly controversial, is the limited and bound nature of our perceptions and minds. We’re animals, and while our perceptual and mental capabilities are pretty amazing, it’s rather clear that they have their limits and that much of reality—in the sense of what’s out there, outside the contents of our minds—is simply inaccessible to us. I don’t mean just inaccessible to our hearing, vision, etc., because our ability to build new technologies has enabled us to go well beyond those, and progress means we can go beyond them further still. I mean much of reality is inaccessible to us conceptually. Our brains have limits on what they can think and what tools they can bring to thinking, and that means the world outside of them has aspects we can’t even think about.

I find all this obvious, because it’s uncontroversially the case for other animals. There are things my brain is capable of wrestling with and understanding that my dog—who isn’t even all that dumb by dog standards—just can’t, no matter how much technology he might have access to (he wouldn’t know how to use it), or how much education one might direct at him (he couldn’t internalize it). His brain is limited compared to a human’s, just like a fish’s brain is limited compared to his. And it would be awfully odd, and entirely unjustified, to imagine that our brains somehow are so advanced that they escape—or are capable of someday escaping—such limits entirely. No matter how much we reason, no matter how much we think we’re applying boundless logic, we’re still just animals.

That’s not bad, of course. We do lots of astonishing things, make tons of cool discoveries, and still have a long way to go. But to believe that our reason is unlimited, our potential understanding unbounded, is to engage in fantasy.

I was recently rereading one of my favorite books, Bryan Magee’s Confessions of a Philosopher. It’s an intellectual autobiography of an overwhelmingly lush mind, and in my opinion the best book ever written about what it’s like to pursue a life entirely devoted to philosophical exploration—and why such a life can be appealing, or even imperative, to some. And I came across this passage, which puts into clear and direct prose my own long-held, but rather inchoate, thoughts on the limited nature of our reason, and my strong reaction against assertions of its boundlessness. I’m going to quote it in full, with only light edits. (As well as a couple of added paragraph breaks, mostly for aesthetic reasons, because Magee insisted on writing pages without them—with purpose, I’m sure, but this is my blog, so I can officiously revise.)

[Those who insist on boundlessness] seemed to believe that everything was explicable in the light of reason, that rational enquiry would eventually make all desirable discoveries, and that in principle if not altogether in practice all problems could be solved by the application of rationality. ... My problem was that their own positive beliefs seemed to me manifestly untenable, and their attitudes—well, perhaps not quite as comfortable and complacent as those they criticized, but comfortable and complacent none the less. They seemed to think that the world was an intelligible place, and I did not see how in the light of a moment's thought this belief could be entertained. Their faith in the power of reason seemed to me almost unbelievably unreflecting and misplaced in view of the fact that it was the application of reason that perpetually gave rise to insoluble problems, problems that were brought into existence by thinking but could not be removed by it.

With many such people, belief in the power of reason was an ideology. They believed in it uncritically and on principle, and were totally dismissive of any dissenting voice. They never reflected seriously on the narrowness of the range within which reason is applicable, or its propensity for self-contradiction, or its manifest inability to solve most of the fundamental questions about experience. Any attempt on my part (or anyone else’s) to draw their attention to these things smacked to them of religion, which they equated with superstition, and of which they tended to be contemptuous. It was self-evident to them that this world of experience is all there is, and anything we do not as yet understand about it we can reasonably hope to discover in the course of time. …

[Y]ou do not have to reflect deeply, you do not need even to go beyond what a child is capable of thinking, to realize that our experience is unintelligible to ourselves in its most general and basic features and yet the sort of people I am talking about seemed not to have made that discovery. To them it seemed self-evident that some sort of commonsense view of things must be, by and large, right, whereas I saw it as self-evident that common sense could not possibly be right, since reasoning logically from it as a starting point led one almost immediately into a morass of incomprehensibility and self-contradiction. In fact, to put it baldly yet truthfully, they found the denial of the commonsense view of the world ridiculous whereas I found the acceptance of the commonsense view of the world ridiculous. Their whole outlook was one that could survive for only so long as they did not reflect on its foundations. Not only was it superficial in the extreme, it was also detached, floating in mid-air, unsupported and unsustainable. Any fundamental questioning of it by anyone was dismissed as uninteresting and pointless. If one drew their attention to the fact that there seemed to be no way in which our reasoning powers could make sense of this or that basic feature of the world or of our experience, this was seen by them as a reason for not raising the question. What they wanted to do was confine their lives to the domain within which they could make sense of things.

This all seems to me quite right.

What’s more, the idea that there’s a whole world out there we not only can never know, but to some degree can’t even get a sense of the kinds of things we can’t know, is rather wondrous. 

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