Explaining behavior

After observing that lots and lots of genes can interact to determine a particular phenotype, Razib asks some good questions about Social Science:

I’ve been thinking about this when it comes social phenomena. Much of the verbal treatment presupposes a few large effect explanatory variables; but what if that’s not correct? What if most social phenomena are contingent upon thousands of small effect predictors? How are you going to talk about this? And since we don’t know the “gene” unit of social phenomena where do you even start? Of course quantitative social scientists focus on phenomena which do have independent variables of big effect; but most of the action might not be low hanging fruit, but rather dispersed in the canopy.

I’ll just observe that underlying any gene explanation, even ones that have many, many causal genes, is genetic theory (“One explanation to rule them all”) itself. When social scientists are trying to describe a particular behavior (e.g. why Davis undergrads go to The Graduate on Friday nights) then they may have to go after a multitude of explanations. If they’re trying to describe a type of behavior (e.g. demand for alcoholic beverages), this may not be the case.

UPDATE: I wrote this as a comment below, but I thought it fit better up here:
“I think his critique confuses a couple of things. First of all, there are several levels of abstraction even in the hard sciences. Chemists don’t reduce everything they study into sub-atomic behaviors and certainly biologist and geneticists don’t. Even if everything can be reduced, sometimes the emergent behaviors are so complex we, with our feeble minds, have to strip some of the complexity away. In other words, chemist *could* talk about sub-atomic behaviors of their chemicals — which represent billions of interactions between billions of sub-atomic particles — but they don’t, mostly because they, being human, aren’t suited for it.

The other thing he seems confused by, and this may be related to the first confusion, is the nature of social science. We’re not about predicting particular behaviors. We’re about predicting types of behaviors. Sometimes you hear a critique of economics suggesting we’re bad at predicting business cycles and so we don’t know much about business cycles. This is clearly false, we know a bunch about business cycles just as chemist know a bunch about specific chemical reactions. Do chemist not know chemistry because they can’t predict the velocity of a particular molecule during a reaction? Do they not know chemistry because they can’t predict the exact timing when a particular reaction will take place between two molecules (or if it will happen at all)? These questions are funny because we wouldn’t even suggest chemists should know these particular things.

I guess I’m saying social science is about general patterns of social interaction. This upsets people who want us to be seers.”

9 thoughts on “Explaining behavior”

  1. I’m not really sure myself because Razib doesn’t really provide examples. I think he’s making the general case that social phenomenon may not be explainable by just few causal variables. In the hard sciences, reduction just seems to match reality. Everything is just a few sub-atomic particles and all phenomenon just derives from their properties. Maybe social reality is different, he’s making the case that there is no equivalent sub-atomic particles. Or he may be arguing that there are sub-atomic particles (psychology or whatever) but that they’re so varied that behavior can’t be explained by just understanding a the structure of a few of those varieties.


  2. The classic example of this abstraction discusses the air in a balloon. Trillions upon trillions of collisions happen between the air molecules in a balloon every second, and their sum is what we call “pressure.”

    The difference between economists and chemists is that chemists are better at controlling and repeating their experiments.

    Maybe economics is a deep abstraction of chemistry.

  3. I think the observation about experiments is right and clearly economics is an abstraction of psychology which is an abstraction of biology which is an abstraction of chemistry.

  4. No, no, no… economics and psychology have distinct areas of enquiry. Robbins said it best. And then there was that Michael G. post on “neuroeconomics”.

  5. True. But its also true that physics and chemistry have distinct areas of inquiry even though the latter can be reduced to the former.

    This is actually my point. Everything is reducable to sub-atomic particles. We just have feeble little brains so we make abstractions. Razib was saying abstracting social phenomenon is impossible and the reply is “no its not”.

  6. The real question is how useful those abstractions are. Heat and air pressure, as abstractions, are convenient conceptual tools because they allow consistent predictions. We can predict that thermal energy will flow from hot objects to cold objects, or how kinetic energy will flow from a region of high pressure to a region of low pressure to a high level of precision.

    You can’t predict the price of bacon with the same degree of certainty. This upsets people who want you to be seers.

  7. The seers line is brilliant… sounds familiar though. :-)

    So what do economists know about business cycles and what use is that knowledge? Sounds like a good theme for a series of posts. Gabriel? :-)

  8. What was that line from the TED conference? “Economists have successfully predicted nine of the last four recessions!” or something like that?

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