Is studying the brain a good way to understand the mind? Does psychology stand to brain anatomy as physiology stands to body anatomy? In the case of the body, physiological functions—walking, breathing, digesting, reproducing, and so on—are closely mapped onto discrete bodily organs, and it would be misguided to study such functions independently of the bodily anatomy that implements them. If you want to understand what walking is, you should take a look at the legs, since walking is what legs do. Is it likewise true that if you want to understand thinking you should look at the parts of the brain responsible for thinking?

Is thinking what the brain does in the way that walking is what the body does? V.S. Ramachandran, director of the Center for Brain and Cognition at the University of California, San Diego, thinks the answer is definitely yes. He is a brain psychologist: he scrutinizes the underlying anatomy of the brain to understand the manifest process of the mind. He approvingly quotes Freud’s remark “Anatomy is destiny”—only he means brain anatomy, not the anatomy of the rest of the body.

But there is a prima facie hitch with this approach: the relationship between mental function and brain anatomy is nowhere near as transparent as in the case of the body—we can’t just look and see what does what. The brain has an anatomy, to be sure, though it is boneless and relatively homogeneous in its tissues; but how does its anatomy map onto psychological functions? Are there discrete areas for specific mental faculties or is the mapping more diffuse (“holistic”)?

The consensus today is that there is a good deal of specialization in the brain, even down to very fine-grained capacities, such as our ability to detect color, shape, and motion—though there is also a degree of plasticity. The way a neurologist like Ramachandran investigates the anatomy–psychology connection is mainly to consider abnormal cases: patients with brain damage due to stroke, trauma, genetic abnormality, etc. If damage to area A leads to disruption of function F, then A is (or is likely to be) the anatomical basis of F.

This is not the usual way that biologists investigate function and structure, but it is certainly one way—if damage to the lungs hinders breathing, then the lungs are very likely the organ for breathing. The method, then, is to understand the normal mind by investigating the abnormal brain. Brain pathology is the key to understanding the healthy mind. It is as if we set out to understand political systems by investigating corruption and incompetence—a skewed vision, perhaps, but not an impossible venture. We should judge the method by the results it achieves.

Ramachandran discusses an enormous range…