Interesting Things I’ve Been Reading: Causality Edition

This post is the first in a series that will link to the things I’ve read in the past year or so. I’m going to try to group these thematically, and why not start with a big picture issue: causality.

Causality seems to be embedded in the world around us, but this could be largely due to its being deeply embedded in our psychology. Empirically speaking, establishing a causal relationship between phenomena is actually quite tricky since there is no completely logical way to do so! If event B always follows event A, all you have definitively is that up until now, B has followed A. There’s no guarantee that such a relationship will continue. Even if it were to continue, there may be some hidden C that is causing A first and B next, so that the two always occur in sequence, but are not in fact, causally related. This perspective on causality is essentially the one described by David Hume. For a more detailed discussion check out

http://www.iep.utm.edu/hume-cau/

The econ-blogger Karl Smith takes a view that attempts to simply dodge the whole thorny business:

http://modeledbehavior.com/2012/01/11/causality-is-superfluous/

What he is describing in the post above is a deterministic view of the universe—in fact, an essentially classical (that is, non-quantum) view of the universe. Thus, patterns in time, including things we interpret as cause-and-effect relations are simply a form of geometrical shape that we are forced to map as we proceed through the universe’s time dimension.

Of course, quantum mechanics radically alters this perspective. If you regard the collapse postulate as an approximate description of decoherence, then a global view of some large-scale system will probably look something more akin to the many worlds interpretation of quantum mechanics. That definitely doesn’t look like a block!

But without getting too exotic, the issue of causation versus correlation is extremely important. We tend to want to read causation into correlations, but we have to be careful. Here’s a good article describing problems this gives rise to in medicine:

http://www.wired.com/magazine/2011/12/ff_causation/all/1

Depending on my energy level, I may post some more about causality. But this is enough for now.

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