Wednesday, May 20, 2015

Chris Dillow — "Consistent with"

In discussing Paul Romer's wonderful concept of mathiness*, Peter Dorman criticizes economists' habit of declaring a theory successful merely because it is "consistent with" the evidence. His point deserves emphasis. 
If a man has no money, this is "consistent with" the theory that he has given it away. But if in fact he has been robbed, that theory is grievously wrong. Mere consistency with the facts is not sufficient.….
The difference between causes and reasons. Reasons are not necessarily causes. "The dog ate my homework."

There may be different plausible explanations for — reasons consistent with — the same data. 

Science is about establishing causal explanation in terms of "mechanism" or "transmission."

Otherwise, it is handwaving.
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 - a point which is lost in the discipline's mathiness.
Stumbling and Mumbling
"Consistent with"
Chris Dillow | Investors Chronicle

See also

Lars P. Syll’s Blog
Consistency and validity is not enough!
Lars P. Syll | Professor, Malmo University

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