Stability: an epidemiological ingredient in the realism debate?

I’m preparing a talk on stability for the New Thinking in Scientific Realism Conference that opens in Cape Town tomorrow. I introduced the notion of stability in my book, defined like this:

“A result, claim, theory, inference, or other scientific output is stable if and only if

(a) in fact, it is not soon contradicted by good scientific evidence; and

(b) given best current scientific knowledge, it would probably not be soon contradicted by good scientific evidence, if good research were done on the topic.” (Broadbent 2013, 63)

The introduction of this notion was a response to the perceived difficulties around “translating” epidemiological (or more generally biomedical) findings into good health policy. At Euroepi in Porto, 2012, I argued that translation was not the main or only difficulty for using epidemiological results, and that stability – or rather, the lack of it – was important. After all, one cannot comfortably rely on a result if one cannot be confident that the next study won’t completely contradict it, and that seems to happen pretty often in at least some areas of epidemiological investigation.

Thus the reasons for introducing the notion were thoroughly practical. More recently, though, I have been trying to tighten up the philosophical credentials of the notion, and that’s what I’m going to be talking about in Cape Town. Is stability epistemically significant? Can it be shown to be epistemically significant without collapsing into approximate truth? Can it be distinguished from approximate truth without collapsing into empirical adequacy? These are the questions I will seek to answer.

What’s interesting for me is that, as far as I can see, it’s pretty easy to answer these questions affirmatively. If I’m right about that, then this will be a nice case where studying actual science gives rise to new philosophical insights. The desire to make public health policy that will not have to be revised six months down the line is eminently practical; yet the proposal of a status that scientific hypotheses might have, distinct from truth and empirical adequacy and all the rest, is eminently abstract. If stability really is both defensible and novel, then it will illustrate the oft-repeated mantra that philosophers of science would benefit from looking more closely at science. I am personally put on guard when I hear that said, not because I disagree in principle, but because experience has taught me to suspect either lip service, or an excuse for poor philosophy. Perhaps I’m also guilty of one or both of these; I will be interested to see what Cape Town says.

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