Ethics

Split Brains and Irrationality

By Adam Kolber

Larry Solum of the Legal Theory Blog has sent me a shout-out of sorts (at the bottom of his post here), asking my opinion about this blog post at "Philosophy of Brains".  In the latter post, Adam Leonard discusses Mike Gazzaniga's work on split brains and suggests that the line of research reveals an "interpreter" function in the brain that may explain an awful lot about our behavior and our explanations of our behavior.  Here's the most controversial paragraph:

The existence of the interpreter function has been known for over twenty years, and has been incorporated into Psychology?s explanations of self-deception, self-serving biases, cognitive dissonance, and defense mechanisms of the ego. What scientists have not yet addressed, however, is the possibility that the interpreter function explains how Man can be a tribal territorial animal (with DNA 98% the same as chimpanzees!) but totally unaware of any animal instincts affecting his behavior. ? Is it possible that our chronic irrational behavior may actually be driven by instincts, but the interpreter covers this up by generating rational explanations for our irrational behavior, and convincing us the explanations are true? ? Is it possible that the reason Man has never been able to live in peace is simply that as tribal territorial animals we compulsively form tribes and war with one another? ? Is it possible that is also why we compulsively take sides and argue issues ? such as this one ? angrily and irrationally, as if they were territory to be taken or defended?

Here are some thoughts:

(1) I don't think we're "totally unaware of any animal instincts" that affect our behavior.  I imagine that we understand our urges to eat, have sex, breathe, etc. as animal instincts in some sense, even if they get fancied up a bit in our culture. (By the way, I tend to be skeptical of DNA percentage similarity claims.  The issue has been noted a bit before on the Neuroethics & Law Blog.)

(2) "Is it possible that our chronic irrational behavior may actually be driven by instincts" that the interpreter covers up with rational explanations?  I think a lot of the recent work in neuroeconomics and behavioral economics indeed demonstrates that we often make decisions that are at odds with what a fully-informed, perfectly rational creature would do.  I'm not sure what role "the interpreter" plays here and how precisely it is meant to connect with split-brain research.  For one thing, I suspect that we often have no even-purportedly-rational story to tell ourselves (see, e.g., Jonathan Haidt et al.'s work on moral dumbfounding).  Also, as for people with healthy human brains, we manage to give relatively good explanations of our behavior relative to those with so-called split brains.  This suggests that any interpreter function derived solely from our understanding of split brains can only have limited applicability to those with healthy human brains.

(3) I think the last couple of questions are extraordinarily speculative.  I don't think that we "compulsively" form tribes and war.  Surely one can resist the urge to go to war.  But I certainly take these questions to be interesting ones, and so I won't defend any territory here "angrily and irrationally"!

Full post as published by Neuroethics and Law on March 11, 2008 (boomark / email).