The human mind is therefore left, in the first place, with a cheerful pragmatism. Like the cartoon strip centipede, I can’t say which mental foot comes first. I simply move. I have to. And the human mode of survival is called “intelligent” because the human brain contains sense-data-processing systems that enable us to categorize and manipulate sense-data memories and categories of memories (concepts), then devise action plans that get us good results when they are put into practice. Our thinking systems enable us to plan and execute survival-oriented behaviours at least two levels more prescient than those seen in any other species, even though these systems are all arbitrary and tentative.

They are arbitrary in the sense that they do not, as Plato would say, “cut nature at the joints.”² They do not divide the data we get from reality at the places where it actually falls into categories of things. Under a modern scientific view of reality, nature has no joints. There are no universals. There aren’t even any terms that reliably name individual entities. Even I am not the I that I was ten years ago. Not even ten minutes ago.

However, the human styles of evolving new concepts and behaviour patterns by constant mental and cultural reprogramming are very much not arbitrary in a deeper sense. We cannot function without concepts by which to organize our sense data and respond to them. If a vital program is to be retired, that can happen only when a replacement is ready to be put in. Hazards and predators are everywhere. We humans are slow and weak. Yet we dominate our planet to a degree unparalleled by any other species in the history of Earth. Using our minds filled with concepts, we have devised practical skills, technologies, production teams, communities, and cultures, and we flourish. This is how I conceive of and explain our concepts about concepts.

In the second place, the mind is left with a picture of itself that amounts to a kind of realistic humility. If reality is that slippery and hard to grasp, I have to accept that, in it, I can never become smug about my way of thinking. It may prove inadequate at any time, no matter how carefully I have worked it out, and no matter how vigilant I am. I may have to revise at any time. An honest, modern thinker has to gamble on gambling as being the best gamble. I may be tough, smart, and versatile, but I will still have to grow and change in this world until the end of my days, and so will everyone I know. I accept that. It is a way of conceiving of my existence that makes life look frightening and unnerving—and challenging and exciting.