There is nothing really profound being stated so far. But when we come to applying this theory to philosophies, the implications are a little startling.

Other than rationalizations, the rationalists have nothing to offer.

What are Plato’s ideal “forms”? Can I measure one? Weigh it? If I claim to know the forms and you claim to know them, how might we figure out whether the forms you know are the same ones I know? If, in a perfect dimension somewhere, there is a form of a perfect horse, what were creatures called eohippus and mesohippus (biological ancestors of the horse), who were horsing around long before anything Plato could have recognized as a horse existed?

Similarly, we can ask: What are Descartes’s “clear and distinct ideas?” Clear and distinct to whom? Him? His contemporaries? To me, they do not seem so clear and distinct that I can base my thinking on them and thus stake my sanity and survival on them. Many people have not known what he was talking about. Not in any language. Yet they were, and are, fully human people. Some of Descartes’s favourite clear and distinct ideas—the basic ideas of arithmetic and geometry—are unknown in some human cultures.

This evidence suggests strongly that Descartes’ categories are simply not that clear and distinct. If they were inherent in all human minds, all humans would develop these ideas as they matured, a point first noted by Locke. Looking at a broad spectrum of humans, especially those in other cultures, tells us that Descartes’s clear and distinct ideas are not built in. We acquire them by learning them. Arguing that they are somehow real, and that in the meantime sensory experience is illusory, is a way of thinking that can then be extended to arguing for the realness of the creations of fantasy writers. In The Hobbit, J.R.R. Tolkien describes Ents and Orcs, and I go along with the fantasy for as long as it amuses me, but there are no Ents, however much I may enjoy imagining them.

                                                                                                                                                                         

                                                                        J.R.R. Tolkien

On the contrary, all concepts are merely mental models that help us to organize our memories in useful ways that make it easier for us to plan and then act. Even ideas of numbers, Descartes’s favourite “clear” ideas, are merely mental tools that are more useful than Ents. Counting things helps us to act strategically in the material world and thus to survive. Imagining Ents gives us temporary amusement—not a bad thing, though not nearly as useful as an understanding of numbers.

But numbers, like Ents, are mental constructs. In reality, there are never two of anything. No two people are exactly alike, nor are two trees, two rocks, two rivers, or two stars. So what are we actually counting? We are counting clumps of sense data that approximate concepts built up from memories of experiences. Concepts far more useful in the survival game than the concept of an Ent. And even those concepts that seem to be built into us (e.g., basic language concepts) became built in because, over generations of evolution of the human genome, those concepts gave a survival advantage to their carriers. Language enables improved teamwork; teamwork works. Thus, as a physically explainable phenomenon, the human capacity for language also comes back into the fold of empiricism.

Geneticists can locate the genes that enable a developing embryo to build a language centre in the future child’s brain. Later, perhaps, MRI scanning can find the place in your brain where your language program is located. If you have a tumour there, a neurosurgeon may fix the “hardware” so that a speech therapist can help you to fix the program. The human capacity for language is an empirical phenomenon all the way down.²

In the meantime, counting enabled more effective hunter-gatherer behaviour. If a tribe leader saw eight of the things his tribe called deer go into the bush and if only seven came out, he could calculate that if his friends caught up, circled around in time, and executed well, if they worked as a team and killed, this week the children would not starve. Both the ability to count things and the ability to articulate detailed instructions boosted a primitive tribe’s odds of surviving.

Thus were the rudiments of arithmetic and language built up in us. And if the precursors of language seem to be genetically built in—for example, human toddlers all over the world grasp that nouns are different from verbs—while the precursors of math are not, this fact would only indicate that basic language concepts proved far more valuable in the survival game than basic math ones. (Really useful concepts, like our wariness of heights or snakes, get written into the genotype.) The innate nature of language skills would indicate that neither basic language concepts nor basic arithmetic concepts are coming to us by some mysterious, inexplicable process out of Plato’s ideal dimension of the pure Good.

We do not have to believe—as the rationalists say we do—in another dimension of pure thought, with herds of “forms” or “distinct ideas” roaming its plains, in order to have confidence in our own ability to reason. By nature or nurture, or by subtle combinations of the two, we acquire and pass on to our children those concepts that enable their carriers, that is, us, to survive. In short, reason’s roots can be explained in ways that don’t assume any of the things that rationalism assumes.