Continue reading this post…

Galileo offered a thought-experiment that showed, contrary to common beliefs, that objects can move without any forces pushing them along at all. It sounds trivial and yet this was the breakthrough that made physics and the rest of modern science possible. Galileo’s reasoning was undeniable: roll a ball down an incline, it speeds up; roll it up an incline, it slows down. So, if you roll it onto a frictionless horizontal surface, it will have to go forever. Stands to reason, by common sense. But that simple bit of reasoning destroyed the Aristotelian world-picture and ushered in science. Starting there, 400 years of continually remodeling everyday experience has produced a description of reality incompatible with common sense; that reality includes quantum mechanics, general relativity, natural selection and neuroscience.

Descartes and Leibniz made important contributions to science’s 17th-century “take off.” But they saw exactly why science would be hard to reconcile with historical explanation, the human “sciences,” the humanities, theology and in our own interior psychological monologs. These undertakings trade on a universal, culturally inherited “understanding” that interprets human affairs via narratives that “make sense” of what we do. Interpretation is supposed to explain events, usually in motivations that participants themselves recognize, sometimes by uncovering meanings the participants don’t themselves appreciate.

Natural science deals only in momentum and force, elements and compounds, genes and fitness, neurotransmitters and synapses. These things are not enough to give us what introspection tells us we have: meaningful thoughts about ourselves and the world that bring about our actions. Philosophers since Descartes have agreed with introspection, and they have provided fiendishly clever arguments for the same conclusion. These arguments ruled science out of the business of explaining our actions because it cannot take thoughts seriously as causes of anything.

Descartes and Leibniz showed that thinking about one’s self, or for that matter anything else, is something no purely physical thing, no matter how big or how complicated, can do. What is most obvious to introspection is that thoughts are about something. When I think of Paris, there is a place 3000 miles away from my brain, and my thoughts are about it. The trouble is, as Leibniz specifically showed, no chunk of physical matter could be “about” anything. The size, shape, composition or any other physical fact about neural circuits is not enough to make them be about anything. Therefore, thought can’t be physical, and that goes for emotions and sensations too. Some influential philosophers still argue that way.

Neuroscientists and neurophilosophers have to figure out what is wrong with this and similar arguments. Or they have to conclude that interpretation, the stock in trade of the humanities, does not after all really explain much of anything at all. What science can’t accept is some “off-limits” sign at the boundary of the interpretative disciplines.

Ever since Galileo, science has been strongly committed to the unification of theories from different disciplines. It cannot accept that the right explanations of human activities must be logically incompatible with the rest of science, or even just independent of it. If science were prepared to settle for less than unification, the difficulty of reconciling quantum mechanics and general relativity wouldn’t be the biggest problem in physics. Biology would not accept the gene as real until it was shown to have a physical structure — DNA — that could do the work geneticists assigned to the gene. For exactly the same reason science can’t accept interpretation as providing knowledge of human affairs if it can’t at least in principle be absorbed into, perhaps even reduced to, neuroscience.

That’s the job of neurophilosophy.

This problem, that thoughts about ourselves or anything else for that matters couldn’t be physical, was for a long time purely academic. Scientists had enough on their plates for 400 years just showing how physical processes bring about chemical processes, and through them biological ones. But now neuroscientists are learning how chemical and biological events bring about the brain processes that actually produce everything the body does, including speech and all other actions.

Research — including Nobel-prize winning neurogenomics and fMRI (functional magnetic resonance imaging) — has revealed how bad interpretation’s explanations of our actions are. And there are clever psychophysical experiences that show us that introspection’s insistence that interpretation really does explain our actions is not to be trusted.

These findings cannot be reconciled with explanation by interpretation. The problem they raise for the humanities can no longer be postponed. Must science write off interpretation the way it wrote off phlogiston theory — a nice try but wrong? Increasingly, the answer that neuroscience gives to this question is “afraid so.”

Few people are prepared to treat history, (auto-) biography and the human sciences like folklore. The reason is obvious. The narratives of history, the humanities and literature provide us with the feeling that we understand what they seek to explain. At their best they also trigger emotions we prize as marks of great art.

But that feeling of understanding, that psychological relief from the itch of curiosity, is not the same thing as knowledge. It is not even a mark of it, as children’s bedtime stories reveal. If the humanities and history provide only feeling (ones explained by neuroscience), that will not be enough to defend their claims to knowledge.

The only solution to the problem faced by the humanities, history and (auto) biography, is to show that interpretation can somehow be grounded in neuroscience. That is job No. 1 for neurophilosophy. And the odds are against it. If this project doesn’t work out, science will have to face plan B: treating the humanities the way we treat the arts, indispensable parts of human experience but not to be mistaken for contributions to knowledge.



Alex Rosenberg is the R. Taylor Cole Professor and philosophy department chair at Duke University. He is the author of 12 books, including “The Philosophy of Science: A Contemporary Approach,” “The Philosophy of Social Science” and, most recently, “The Atheist’s Guide to Reality.”