If, by chance or interest, you have been following contemporary neuroscience, the expression “Are you out of your mind?” should be shelved in favor of the expression “Are you out of your brain?” Or, more accurately, if more cumbersomely, we should ask, “Are you out of your mind=brain?”

This would bring our language up to speed with modern neuroscience (it might also, however, confuse my children and yours). After all, most of the neuroscientists, philosophers of mind, and others who write about the human brain, speak of it as the organ that we think with. It is easy enough to assume the truth of this dubious claim by absorbing, like a sponge, stories in the media that propagate it.

As if to press the Delete key on the views of untold numbers of thinkers who have argued, for centuries, that thinking cannot be reduced to a physical organ of the human body, or more recently, that thinking cannot be reduced to the brain and central nervous system, today’s neurobiologists and neurophilosophers do precisely that: they say that thought can be explained largely by reference to the brain’s electrical-chemical processes.

Neurophilosophers such as Patricia Churchland and Daniel C. Dennett have argued that the mind equals the brain. Thinking, for them, is simply the result of the firing of neurons, neural connections, and various material forces taking place in the brain. As Dennett says, the soul is really a bunch of “robots” and these “robots” are “the mindless swarms of neurons and other cells that cooperate to produce a thinking thing—just not an immaterial thinking thing.” Therefore, psychology is really biology for such contemporary brain scientists.

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To be sure, thinking presupposes a functioning brain, but it cannot be reduced to this fist-sized organ. Thinkers ranging from Aristotle (d. 322 BC) and Aquinas (d. 1274) to Mortimer Adler (d. 2001) and Benedict Ashley, O.P. (d. 2013), have shown that thinking is a spiritual or immaterial power of the human person (and only the human person), not a material property.

For instance, in the Summa Contra Gentiles, St. Thomas Aquinas gives five arguments to show why the intellect and the senses, or, as we would say today, why the mind and the brain are not the same. They hold up just as well today as when Aquinas formulated them over 700 years ago, and they have been further developed and refined by Ashley and others.

First, Thomas argues that both human beings and animals possess sense, but only the former have an intellect. The truth of this comes from the observation that animals act in a determined and uniform way by instinct, whereas humans are able to act freely in diverse ways for a goal. That is, humans can think about the best means to realizing the goal they seek and then freely choose it. This is evidence that intellect and sense cannot be equated (Ashley deals with recent studies attempting to show that animals can use language. But he shows that only humans speak a syntactical one; see Ashley, Healing for Freedom, pp. 183-88).

Second, Thomas notes that while the sense power is aware of singulars, the intellect is aware of universals. This is because every sense power knows through individual species, since it receives the species of things in bodily organs. Ashley gives the example of how we can think of both five apples and five oranges (species), but also the number five (universals) (see Healing for Freedom, p. 190).

Third, Thomas observes that our senses take in only material things. The sense organs do this by being physically as neutral as possible to a sensible quality (e.g., eye to color). Thus, I can see red roses without my eyes actually becoming red roses. Or, I can hear a sound without my ears literally becoming that sound. Sensible qualities are the proper object of the senses and exist only in them, not in the intellect. The senses are bereft of knowledge without these sensible properties. On the other hand, the intellect knows non-bodily things, such as wisdom, truth, and the relations existing between things (Ashley notes that this is especially evident in the use of human language, whereby we can assert and know propositions as either true or false; see Healing for Freedom, p. 193).

Fourth, a sense knows neither itself nor its workings. Thomas gives the following example: sight neither sees itself nor sees that it sees. This self-reflexive power (or self-consciousness)—i.e., knowing that you know something—belongs to the intellect alone. Ashley explains this by pointing out that an extended body cannot have every part of its body be in contact with every other part. That is why the human brain, as a material thing having quantity, is unable to have this reflexivity: it is a network of neurons connecting one point of the brain with as many other points of the brain as possible. But no matter how much we compress a body (such as the brain, if that were possible without destroying it) and no matter how interconnected its points by the transmission of signals, we cannot place every part in contact with every other part (see Healing for Freedom, p. 198). So, once again, we can affirm that intellect and sense are different.

Fifth, sense is corrupted by too much of a sensible object. Stated another way, our senses can be overloaded, e.g., the sun can blind one’s eyes. But intellect is not corrupted or overwhelmed by thinking about superior concepts. In fact, knowing abstract and universal concepts makes someone better equipped to understand lesser things later on. So, while our eyes can have too much sunlight, our minds cannot have too much knowledge of God. The sensitive power therefore differs from the intellective power (see Ashley’s discussion of this argument in Healing for Freedom, pp. 199-203, as well as how he relates it to Goedel’s Theorem on pp. 198 and 202-03).

What causes serious problems for the materialist view is that the materialist understanding of the brain makes a mockery of the scientific enterprise itself, in that the materialist brain researcher holds up his research as proof that we think with our brains and in fact appeals to this evidence to convince you and me of the truth of his position. In making this move, the materialist is appealing to a free will that we, in his worldview, actually no longer really have—it’s an illusion too. But if freedom is an illusion, it renders his scientific appeal rather unscientific, as well as unworkable. He is, in other words, caught in a contradiction.

That is, if he is right to deny that thinking is an immaterial process, then he can no longer coherently try to persuade us to “come over” to his way of understanding things. We are in fact already determined: some of us are determined to “think” he is right and some of us are determined to “think” he is wrong, all depending on the particular physiochemical activity going on in our brains. (An early version of this “self-referential” argument against determinism, by Joseph Boyle and his co-authors, is proposed here.)

We are surely not free, according to this view, either to accept or reject the materialist’s argument equating the mind with the brain. But if we actually are free, then we could not in truth equate the mind with the brain, since free choice, like our ability to know, is a spiritual power not dependent on anything material. Science then, by the logic of materialism itself, can no longer be about the rational pursuit of truth, but about power struggles over fixed, predetermined conclusions. To borrow a recent expression from American politics, “It’s a bridge to nowhere.”

I find Gilbert Meilaender’s expression of the mind-brain relationship much closer to the truth. He says our thoughts are “both located in the brain and distanced from it—which is why we are capable of what [philosopher] Thomas Nagel has called ‘the view from nowhere.’” Nagel, himself an atheist, has gotten into hot water lately with his fellow secular philosophers for questioning the very truth of the materialistic/naturalistic account of mind and cosmos. (See the Public Discourse discussion of Nagel’s book here.)

Many of the neurobiologists who deny the immateriality and existence of the rational and intellectual soul, and who therefore deny the immateriality of thinking, seem never to have heard the ancient and modern arguments for these truths. Or, having heard them, they have either forgotten them or rejected them.

This rejection is often driven by the atheistic and neo-Darwinian assumptions of the prestigious scientists who work in this field. These assumptions must be challenged, however, if science is to retain its rightful place as an inestimable source of knowledge and wisdom in our society. Moreover, it is important to note that not all scientists are atheistic materialists; there are many internationally respected scientists who are firm believers in God, among them the recently deceased Hungarian priest-physicist Stanley Jaki who taught at Seton Hall University in New Jersey.

Science deserves more from its scientists than scientism. And so do human persons, whose own God-given dignity depends on the existence (and the acceptance) of the rational soul and the idea that its “faculties” are the “powers” of knowing and willing—not the powerful inner workings of our brains. In the end, as an “embodied intelligent freedom,” to borrow the recent phrase of Benedict M. Ashley and Kevin D. O’Rourke, man’s marvelous brain serves his thinking; it doesn’t do it for him. If you said it did, I think you’d be out of your mind.