Split Brains and Irrationality

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"!

Comments

[Neil Levy]

Leonard's speculations about the role of instincts seem to be made in ignorance of the heuristics and biases traditions, or the body of work on system 1 v. system 2. We already know a lot about nonrational influences on our behavior.

[Patrick S. O'Donnell]

Indeed, the Hellenistic philosophers knew quite a bit about nonrational and irrational influences on our behavior, and appreciation of same is found among any number of philosophical traditions around the globe. A "fully-informed, perfectly rational creature" is an idealized construction that no philosopher, psychologist or any natural or social scientist of note has ever mistaken for a flesh-and-blood human being....

[Daniel S. Goldberg]

Agreed with the post and the comments thus far. That humans do all sorts of non-rational things and construct narratives to make sense of them seems almost beyond dispute, at least to me.

[Anibal]

Dr.Levy, is right in pointing to the work of cognitive psychologists and the behavioural economists tradition that have been working from decades on the nonrational influence in decision behaviour and rationality in general.
But maybe, the neural susbtrates that support frames, heuristics, scripts or those biases schemes affecting rational behaviour found in many cognitive psychology experiments, have to be considered memorized procedures for adressing particular problems instantiated in those brain regions that mediate distinct kinds of memory, the frontopolar cortex associated with decision making and the limbic system that guide behaviour to foster our prefered choices (akin to Damasio´s somatic marker hypothesis); and in this sense, though Leonard scholasticism is somehow bold, perhaps is right just because mentions the work of brain scientists like Gazzaniga and its interpeter center hypothesis, that in on manner or another could be the neural underpinning of the behavioural findings reported by cogntive psychologists and behavioural economists durng the last years.

[Adam Leonard]

Hi, Adam K,
Re: your comments …

(1) I meant “totally unaware” in the sense that we don’t notice them in real time. Upon pondering our behavior we generally admit that some (like territorial defense and sex) must be instinctive, but we don’t experience them as such, and only deduce it after the fact.

You are correct to be skeptical of DNA percentage pronouncements. Quoting from the Nov 2003 Scientific American article, “The Unseen Genome: Gems Among the Junk” … “Journals and conferences have been buzzing with new evidence that contradicts conventional notions that genes, those sections of DNA that encode proteins, are the sole mainspring of heredity and the complete blueprint for all life. Much as dark matter influences the fate of galaxies, dark parts of the genome exert control over the development and the distinctive traits of all organisms, from bacteria to humans.” … I use the 98% figure only because it is widely recognized, and makes the point that we should expect to have tribal territorial animal traits.

(2) I don’t see the interpreter as having a role in the seemingly irrational but actually cunning ways we deal with each other: they would be irrational if we actually were logical (in the mathematical sense), but since we are not, they are well tuned to work with the way we actually are. (Mark Twain said, “When we remember we are all mad, the mysteries disappear and life stands explained.”)

Although the interpreter function was uncovered through research with split-brain patients, the fact that its influence has been incorporated into psychology’s explanations of various behavioral phenomena seems to indicate that it is indeed applicable to “healthy human brains.”

(3) Yes, my questions are speculative, but I don’t believe extraordinarily so. They seem to me to be a reasonable hypothesis that explains observable reality. May I ask, if “surely one can resist the urge to go to war,” why Man has never succeeded in doing so? Our entire history ever since we evolved has been a history of wars and empires. Endlessly. And the future holds the same promise. It will only be when we understand what drives us to this behavior that we will have any hope of ending it.