'Consistent With'

Chris Dillow:

"Consistent with": ...Peter Dorman criticizes economists' habit of declaring a theory successful merely because it is "consistent with" the evidence. His point deserves emphasis. ...

This is a point which some defenders of inequality miss. Of course, you can devise theories which are "consistent with" inequality arising from reasonable differences in choices and marginal products. Such theories, though, beg the question: is that how inequality really emerged?... And the answer, to put it mildly, is: only partially. It also arose from luck, inefficient selection, rigged markets, rent-seeking and outright theft. ...

Quite often, the facts are consistent with either theory. For example, the well-attested momentum anomaly - the tendency for assets that have risen in price recently to continue rising - is "consistent with" both a cognitive bias (under-reaction) and with rational behaviour; fund managers' desire to avoid benchmark risk.

My point here should be well-known. The Duhem-Quine thesis warns us that facts under-determine theory: they are "consistent with" multiple theories. ...

So, how can we guard against the "consistent with" error? One thing we need is history: this helps tell us how things actually happened. And - horrific as it might seem to some economists - we also need sociology: we need to know how people actually behave and not merely that their behaviour is "consistent with" some theory. Economics, then, cannot be a stand-alone discipline but part of the social sciences and humanities...