The “two separate languages” of neuroscience and psychology

In yesterday’s New York Times, Gary Marcus wrote an op-ed called “The Trouble With Brain Science.”  Writing of big-ticket research projects underway in brain science on both sides of the Atlantic, Professor Marcus writes:

Biology isn’t elegant the way physics appears to be. The living world is bursting with variety and unpredictable complexity, because biology is the product of historical accidents, with species solving problems based on happenstance that leads them down one evolutionary road rather than another. No overarching theory of neuroscience could predict, for example, that the cerebellum (which is involved in timing and motor control) would have vastly more neurons than the prefrontal cortex (the part of the brain most associated with our advanced intelligence).

But biological complexity is only part of the challenge in figuring out what kind of theory of the brain we’re seeking. What we are really looking for is a bridge, some way of connecting two separate scientific languages — those of neuroscience and psychology.


Such bridges don’t come easily or often, maybe once in a generation, but when they do arrive, they can change everything. An example is the discovery of DNA, which allowed us to understand how genetic information could be represented and replicated in a physical structure. In one stroke, this bridge transformed biology from a mystery — in which the physical basis of life was almost entirely unknown — into a tractable if challenging set of problems, such as sequencing genes, working out the proteins that they encode and discerning the circumstances that govern their distribution in the body.

Neuroscience awaits a similar breakthrough. We know that there must be some lawful relation between assemblies of neurons and the elements of thought, but we are currently at a loss to describe those laws. We don’t know, for example, whether our memories for individual words inhere in individual neurons or in sets of neurons, or in what way sets of neurons might underwrite our memories for words, if in fact they do.

The problem with both of the big brain projects is that too few of the hundreds of millions of dollars being spent are devoted to spanning this conceptual chasm. Both projects are making important contributions: the European effort is helping build infrastructure for data integration; the American project is emphasizing the development of state-of-the-art tools for collecting new kinds of data. But as anyone in a field richer in data than theory (like weather forecasting) can tell you, amassing data is only a start.

The success of both the Human Brain Project and the Brain Initiative will ultimately rest not just on the data to be collected but also on what can be done with those data once they are collected. On that, too little has been said.

I’m a bit leery of this.  Professor Marcus’ bridge-building and lawful relations sound like aliases for reductionism.  Say we don’t reduce psychology to neuroscience- say we can never reduce psychology to neuroscience.  So what?  Gödel proved that we will never be able to reduce arithmetic to logic, that arithmetic needs concepts that cannot be derived from rules of logic.  Gödel did not thereby give warrant to mysticism or undermine the rationality of arithmetic, since the only concepts in that category are perfectly mundane.  Just because there is no “lawful relation” between the concept of set and the procedure of modus ponens does not make arithmetic any the less a rational pursuit.

So if it turns out that there is no “lawful relation between assemblies of neurons and the elements of thought,” it does not necessarily follow that psychologist will have to conclude that the phenomena their discipline studies derive from supernatural influences, or that they will have to become magicians, or anything so dramatic as that.  It may just be that the two fields of study will have to plod along as they currently do, operating quite independent of each other despite their superficial similarities.  Of course, it may not turn out that this is the case- perhaps some day one field will be reduced to the other.  But science has nothing to fear should this reduction prove impossible.

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