BEHAVIORISM is psychology’s variant on physicalism, the idea that physical events explain all mental or physiological events. It’s the view that all your private thoughts and experiences—moods, dreams, flights of art and fancy, and what philosophers call qualia—are fully reducible to the material activity of your fleshy body (including bio- and electrochemical events within that body).

A strict behaviorist might say “consciousness is an illusion,” but this doesn’t mean that you have no consciousness, only that it’s a subjective view of something better described physically. (Some very extreme behaviorists might deny even the conscious experience, though how this works is somewhat baffling.)

In some circles, any mention of behaviorism is considered fighting words, yet many who decry behaviorism are in fact behaviorists. Are you a behaviorist? Here’s a test: ask yourself about philosophical zombies. Logically, can they be?

A philosophical zombie (p-zombie) doesn’t shamble around and drool. A p-zombie behaves much like you and me. In fact it behaves exactly like you and me, with the same expressions of belief and desire, same fits and rages, down to the finest nuance. It may roll its eyes or sigh in boredom. But it has no mind, no conscious experience, no point of view, no sentience. It feels no pain (though still cries “ouch” if you poke it). Mentally, it is absent. It is as much a robot as your toaster.

Perhaps a p-zombie is physically or technically impossible, but this isn’t the question. René Descartes, for example, thought that all animals were p-zombies. They behave as if they suffer or love, he said, but are clockwork mechanisms with no feelings and so cruelty to animals is impossible. Humans are not p-zombies, he said, because God has endowed our bodies with minds and souls. To Descartes, human p-zombies are physically impossible by God’s mandate, but not a logical impossibility.

The question is: Does a p-zombie entail a logical contradiction? Is a p-zombie a square circle? If you say yes, you are a behaviorist! Obviously. Because pure logic never creates new information, only transforms it in various ways. The statement “Socrates is mortal” says nothing not already contained in “Socrates is a man” and “All men are mortal.” If behavior controverts p-zombism on the grounds of pure logic, subjective consciousness must logically be in that behavior. In short, you’ve just reduced consciousness to physical states. Congratulations, here’s your B.F. Skinner t-shirt.

But what if you say p-zombies are possible in principle? Then you face a deep quandary. Those around you right now might be p-zombies! How do you know they aren’t? Is your mind the only mind in the world? Can you ever escape the insidious trap of solipsism?

No fair trying to push the burden of proof onto the other side: “Prove that they are p-zombies!” This is dishonest. Normally, simpler explanations are better. You’ve admitted that p-zombieism can fully explain your experience of others, without all the extra clutter of subjectivity. So clearly the burden of proof is to show this extra clutter does indeed exist.

If you’re an ardent anti-behaviorist, but the idea of p-zombies irks you, don’t despair: the quandary has another exit, which is to recognize that even the most anti-scientific among us view the world scientifically, i.e., in terms of models. Models that work. Models that predict.

Take the tree in your front yard. You may only occasionally experience it directly (see it or touch it), but how useful, how much simpler, to model the tree as existing all the time. It explains a lot: the cracks in your driveway, the leaves you must rake in autumn, all that bird poop on the car. Another classic example is electrons. No one has ever seen an electron. You could, if you wish, “explain” the electro/chemical behavior of matter as a complex net of processes or proclivities. But the atomic theory of matter, which includes electrons, connects all these dots into a tidy picture, predicting new events accurately to many decimal places. So electrons are part of our model of the objective world.

So, surely, is consciousness. Human behavior is complex. Viewing it as a deep web of patterns and interlocking dispositions is difficult and thought-intensive. But the idea of a subjective mind “driving” the behavior allows the picture to resolve to a beautiful simplicity. A simpler simplicity, at least.

It’s not that consciousness isn’t reducible to behavior—it is, in the sense that Bernoulli’s Law is “reducible” to the complex interactions of billions of particles. But why make more work? The model of other minds simplifies things, helps us cling to sanity.

This should be enough to crack the foundation of strict behaviorism. Still, can we toss one bone to the behaviorists because subjective minds aren’t as measurable or quantifiable as hard science would like—certainly not as quantifiable as electrons. So behaviorism may still be best for laboratory psychology, but not for daily life, or for “softer” sciences like psychiatry or sociology.

Consciousness has other problems too (consider the mind-body problem, for example). So don’t think this has been the last word. Can it ever be? Indeed, the mysteries and conundrums of the mind will rise again, like a p- zombie trying to eat your brain. Yum.