Knowing and Making

Ben Goldacre  ( @bengoldacre ) does some amazing work combatting folk mythologies in favour of science and real data. He has tens of thousands of readers and twitter followers who - mostly - agree with his philosophy. They spread the message at skeptics meetings, atheist book-signings and the pages of the Guardian. He is a leader in showing how to expose and falsify unsubstantiated claims - not just those of homeopaths, fake-medicine enthusiasts and psychics, but also those of journalists, pharmaceutical companies and anyone at all who makes public claims. So what happened today? Goldacre made the following assertion on twitter this evening: What's the difference between this and a homeopath who doesn't need evidence because he "just believes" that his medicines work? Not much. What's especially notable is that dozens or hundreds of his followers - science aficionados all, I would have thought - replied with their own stories about which particular pr...

George Soros, quoted here , proposes that economics and other social sciences shouldn't be asked to produce testable theories. Because: ...social theories will be judged on their merits and not by a false analogy with natural science. I propose this as a convention for the protection of scientific method, not as a demotion or devaluation of social science. The convention sets no limits on what social science may be able to accomplish I don't quite agree. If we abandon the idea of testable social theories, we do  limit what social science can accomplish. I'd propose an alternative approach. Allow and expect that some social theories will not be testable. In many cases a subjective interpretation of the facts can provide value; whether it's Michael Porter's five forces model of markets, or the Jungian model of storytelling interpreted in ' The Seven Basic Plots '. Other theories, however, will be testable. An economic relationship between growth, inflat...

So, let's say I claim that all swans are white. Prove it, you insist. Well, say I, here's a white swan - here's another one - and here's another. Therefore it's quite likely that the rest of them are white too. You probably wouldn't consider that to be much of a proof. Quite rightly, you'd insist on the scientific standard. Make clear what a counterexample would look like (a black swan) and show that a reasonably comprehensive effort to find black swans has failed. Second best might be a detailed biological analysis of swan DNA and physiology to convince you that they simply don't have the capability to produce black pigment - but even that is not very reliable. After all, by definition I am only analysing the white ones. So why in economics do we accept the equivalent of white swans as "evidence" for macroeconomic theories? If a Keynesian wants me to believe her theory about government borrowing resolving the paradox of thrift, she should tell...

Anthony J. Evans (who kindly linked to my camel story earlier in the year - or as he notes, perhaps not all that kindly) has written a paper about economic counterfactuals . He confirms what's now becoming a mantra among economists (if not their public): economists can't make predictions. However, he says, rather than giving up completely on exploring the future, they should do so with two tools of the economist's imagination: counterfactual analysis and scenario building. Counterfactuals are stories about the past - a retrospective prediction if you will - considering what might have happened had a different decision been taken at a key moment. For example, what if the financial sector had not been rescued by governments in 2008? Or what if governments themselves had defaulted on their debts? Scenarios are possible alternative futures - constructed not so that you can predict which one will happen, but so that you can prepare to understand events as they unfold. Each sce...

Comment from "AAPrescott" on Justin Webb's blog : "From a political point of view I like many of Tom Daschle's policies, but he does talk about 'evidence based medicine'.... As a practitioner of Chinese Medicine I have some unease about this" I hope this says more about the commenter than it does about Chinese medicine.