Monday, January 18, 2016

What's with the pessimism?

Half full?
From Wikimedia Commons.

I remember a conversation in grad school with one of the postdocs in our department about some new result in biology over the course of which he called me a "hardcore reductionist" because of something I said that was rather reductionist. However, I'd really just characterize my view as optimistic about figuring out stuff.

A Twitter conversation with Eric Lonergan (see here) about eclecticism in macroeconomics reminded me about my optimism; I realize many people do not share it.

Eric brought up Hume's "uniformity of nature" -- the basic assumption that goes into any quest for universal laws -- suggesting it might not exist in economics. I agreed it was possible -- and always should be in the back of your mind lest you start seeing pattern where none exists. But do we know that for certain? No.

While Eric's view is closer to a case that we should view various economic models as approximations to a (potentially unknowable) theory, Dani Rodrik's push for an eclectic interpretation of macroeconomic modeling suggests a kind of resignation. He says we should give up looking for a big unifying theory of economics because it does not exist. Rodrik's reasoning must be that he and his colleagues haven't found it, therefore it must not exist.

And (via Mark Thoma) I read Daniel Little:
... Does the phenomenon of [social phenomena] admit of a scientific treatment along the lines of Galileo, Newton, or Lavoisier? 
The answer is resoundingly no. Such a goal displays a fundamental misunderstanding of the social world. Social things and processes at every level are the contingent and interactive result of the activities of individual actors. Individuals are influenced by the social environment in which they live; so there is no reductionist strategy available here, reducing social properties to purely individual properties.
This commits two logical fallacies. The current lack of  a scientific treatment does not mean one does not exist. And the lack of a reductionist strategy does not mean there is a lack of any strategy.

As I commented on Little's blog, even his specific example of not being able to begin to understand a city is contradicted by the existence of work by  M. A. O. Ayeni. From the abstract:
For these uses of the system approach, the concept of entropy, introduced from both thermodynamics and information theory, plays a significant role. ... It emerges that the concept of entropy can be used in studies of urban spatial structure as an integrating concept provided that our terms are defined explicitly and unambiguously.
Apparently Little already knows the final result of this research program. However given that he thinks reduction to agents is the only strategy, he probably hasn't considered maximum entropy approaches.

Now I can understand the pessimism in each case. In economics, we seem to be at the end of a failed research program (microfounded rational utility maximization) that began in the 70s. Pessimism is a natural outcome. And in social science (writ large), there is a bias towards consequential human action rather than mathematical laws. I happen to think there is a lot of room for the latter, but that's because I'm pessimistic about human free will.

But even without the information transfer framework for economics, I'd still be optimistic about finding mathematical explanations of most statistical regularities.

The truth is: we don't know. Lack of a big mathematical theoretical framework (or lack of a successful one) is not evidence one does not exist.


  1. "I'm pessimistic about human free will."

    Meaning you're skeptical of it's existence? For what it's worth, I'm skeptical of it's existence. It was a bit surprising to me to see this from Sean Carroll. It's been a while since I read it, so I'm fuzzy on if I even really understood his point. Time for a reread I guess.

    1. Sean Carroll seems to be describing an "effective free will" that exists -- and for individuals, I think that is a good theory. I think effective free will at the individual agent scale integrates out into effective lack of free will at the society scale.

      With a microscope you have

      atoms ----- human ----- society
      not free --- free --- not free

      So that free will is an effective description at the human scale.

    2. I like the atoms --- human --- society scale breakdown. I was just about to say the same thing (to describe the Smith+Carroll set of scales).

      However, you state (regarding the human scale):

      "I think that is a good theory."

      How can we test it?

    3. You might even be able to fill in another level of scale:

      atoms ----- neurons ----- human ---- society
      not free -- not free -----free ---- not free

      I don't know if that's true, but it's my hypothesis. Here's my justification: neuron replacement devices such as cochlear implants. These are deterministic machines, and yet they apparently induce a pattern of nerve cell firings (for the next set of neurons down the chain) which human can usefully distinguish as different kinds of sounds. I don't see why, in principle, such a deterministic device couldn't be perfected so as to be completely indistinguishable from biological inner ear hair cells (the cells these devices replace), at least in terms of the sounds they transduce. Extending this further, in principle, I don't see what would stop us from doing the same for any other set of neurons in the brain: including all of them.

    4. As with any amplifier, you can eventually reach a level of complexity that "effective free will" is a good model.

      I have a feeling that my computer is near that phase transition ...

    5. Now here's a sci-fi extension of the above: imagine if aggregate humanity or society (being a vast information processing machine) can have very non-human subjective experiences, perhaps on some time scale totally alien to us. It might "think" to itself:

      atoms ----- neurons ----- humans ---- society
      not free ---- not free --- not free ----- free

    6. Re: your computer. Ha!... probably more likely than my "society" above.

  2. BTW, why do you say "amplifier?" For example, for humans, do you means we take in low entropy energy and weak information signals, and then expel high entropy energy and stronger (and modulated) information signals?

    1. Neurons, like transistors, take weak signals and boost them (a neuron will take an input and fire off to several other neurons, that fire off to several more, etc).

      At least that's one model ...

    2. Fortunately for the brain, a lot of neurons fire to inhibit the activation of other neurons. Otherwise we would all be epileptics. ;)

  3. "This commits two logical fallacies. The current lack of a scientific treatment does not mean one does not exist. And the lack of a reductionist strategy does not mean there is a lack of any strategy."

    I agree with you, however dominant economics is deeply anti-scientific and anti Galileo since uses deliberately a wrong language in order to fulfill ideological goals, hence it is just a pseudo metaphysics.
    Economics is a social science, dealing with power and conflicts, it is not a natural phenomenon like the ones observed and studied by the great Galileo using the appropriate and more efficient language available, that is mathematics.
    Capitalism must be studied scientifically and using the appropriate tools, what on the contrary has happened has been building up a parallel universe and assuming earth is completely flat and by superstitious postulates and confused abuse of mathematics trying to demonstrate it. Actually by imaginary postulates claiming having proved earth is very flat. And no matter if they screw up Galileo, Ricardo and intelligence.

    1. One thing to consider is that even in conflicts of power, the law of large numbers has to kick in sometime -- and you can potentially say how those conflicts turn out on average.

      That is the key point: it is impossible to model a gas using atoms. There are ~ 10^23 with 6 dimensions of phase space (3 space, 3 momentum) each. It would take a computer the size of the earth to directly simulate the result.

      But it doesn't matter why the macro is impossible to model using "agents" (too many atoms, or humans are too complex with power conflicts and not following natural laws). The point is that there is a simplification for a large number of observations if you don't get too attached to the idea that individual human behavior is consequential.

    2. As we know from history, and the history of India in particular, "sometime" can take centuries. Even now, caste is powerful is India. Closer to home, race is powerful in the U. S.

    3. Well as a matter of fact there are no some atoms in the gas which set rules for the others or enslave the others creating internal dynamics not so regular and stable.
      However, of course capitalism must be studied scientifically as well as other systems and not on the basis of imaginative pseudo metaphysics or superstition as it happens today.
      Quite important should be define a point of view, causalities and observations which are relevant and math language has to be integrated with others since economics is a social and political science. A logic of working of the system has to be outlined in order to collect the relevant observations and place causalities.
      Thanks for hospitality,


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