On the varieties of prediction

In some of the comments below I engaged in a discussion about the power of prediction, the necessity of skepticism, and so on.  In the format of a weblog the full overgrown shape of one’s thoughts can be somewhat muddled.  For example, I evinced a skepticism of predictions of the future from rational a priori assumptions, and therefore a particular prejudice toward custom & tradition.  But across the set of species of predictions obviously various degrees of skepticism are warranted.  After all, I think it would be ridiculous to be skeptical of an astrophysicist who made a prediction as to the arc of celestial orbits.  The record on these things is rather different in terms of precision & accuracy from predictions of, as a contrast, macroeconomic performance.  It stands to reason that the cudgel of skepticism should be selectively applied to different classes of rational systems and the projections thereof.  On the great chain of predictive being, I would rank it like so:

Formal mathematics – High precision

Physics – Great precision

Chemistry – Good precision

Biology – Modest precision

Economics – Fair precision

Sociology – No precision

To be fair, these are broad-brush generalizations (some economists claim are extremely precise in their formal systems because of the problems with testing their models easily when compared to experimental physicists). But, my point is that whereas I believe that experience tells us that one should put great store in the predictions of physicists and the engineering sciences which derive from physical precepts, much more skepticism is warranted when it comes to the wisdom of economists. This is not to say economics is not a worthy or important field, but the nature of the domain of study is by its nature less tractable than particles or galaxies.  Formal methods clarify in the social sciences, but the simplifying assumptions naturally result in a large margin of error from expectations generated.  Many of the biological sciences span the great middle lands between the precise power of physics and the conditional and caveat girded inferences generated by economic data sets.  On the one hand biophysical work can attain a relatively high level of deterministic precision when it comes to molecular pathways, but it concedes a great deal in generality.  Evolutionary work couched in the language of statistics & probability is far more general, spanning an enormous expanse of space & time, but the predictions are characterized by enormous error bars because of the unaccounted for variables and the random acts of historical contingency.

The human sciences have problems which statistical biological sciences do not, the special nature of humanity and the difficulties of controlled experiments.  During the fall the debate over whether the financial bailout was interfering with corrective market processes was peppered with assertions to the effect that we should not, can not, risk a test of the economic theory!  Of course in the natural sciences testing theories is the ultimate check on both flights of fancy and excessive skepticism, but the falsification process in economics can have very grave pubic policy implications.

From physics to economics you obviously are spanning a great range of disciplines, but the important point is that physics is much simpler than economics.  The problem of complexity is what generally warrants greater skepticism of formal models, projections and predictions in particular social domains.  Social systems may exhibit many interaction effects which mask general dynamics, or, the interaction effects may be so great that general inferences may be trivial in their utility.

And it is not simply in human societies where complexity reigns supreme.  Consider ecological and climatic systems. Here the modern Left has discovered the importance of contingent systems which may be shifted out of equilibrium by modest exogenous shocks.  In contrast, the American Right tends to be sanguine about the threats posed by environmental degradation due to non-linear dynamics on the horizon.  Rather, the American Right focuses on the fragility of social and cultural systems, while assuming the robustness of ecological systems.  The American Left on the other hand assumes a thin model of human culture and society which can absorb shocks and changes in norms and values, as the systems reequilibrate with ease.  Libertarians and a certain species of European conservative are consistent by these lights, the former in their optimism about the possibility of relatively easy change, and the latter in their pessimissm.

I will not offer any judgment as to the accuracy of the perceptions by the Rights and Lefts on the issues above. I only point to these as evidence that the same general cognitive toolkit is universal across ideologies, but the skeptical inclination is often not taken uniformly.  The same variations can be seen when it comes to the trust of rational systems or empirical data.  More on the Right than the Left may accept the compelling logic of comparative advantage, while more on the Left than the Right accept the logic of evolution via natural selection.  More on the Right than the Left may accept evidence on sex differences from psychology and neuroscience, while more on the Left than the Right may accept evidence that sexual orientation has a strong biological component.

As human beings we are not consistent, and our worldviews are filtered through our ideological presuppositions.  But it is important to note the context and processes through which our conclusions and inferences are generated.

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