Critical rationalism

26 Jan, 2019 at 16:24 | Posted in Theory of Science & Methodology | 3 Comments

critical-rationalist-project-history-philosophy_3For realists, the name of the scientific game is explaining phenomena, not just saving them. Realists typically invoke ‘inference to the best explanation’ [IBE] …

What exactly is the inference in IBE, what are the premises, and what the conclusion? 

The intellectual ancestor of IBE is Peirce’s abduction:

The surprising fact, C, is observed.
But if A were true, C would be a matter of course.
Hence, … A is true.

Here the second premise is a fancy way of saying “A explains C”. Notice that the explanatory hypothesis A figures in this second premise as well as in the conclusion. The argument as a whole does not generate the explanans out of the explanandum. Rather, it seeks to justify the explanatory hypothesis …

Abduction is deductively invalid … [but] there is a way to rescue abduction and IBE … What results, with the missing premise spelled out, is:

It is reasonable to believe that the best available explanation of any fact is true.
F is a fact.
Hypothesis H explains F.
No available competing hypothesis explains F as well as H does.
Therefore, it is reasonable to believe that H is true.

This scheme is valid and instances of it might well be sound. Inferences of this kind are employed in the common affairs of life, in detective stories, and in the sciences …

People object that the best available explanation might be false. Quite so – and so what? It goes without saying that any explanation might be false, in the sense that it is not necessarily true. It is absurd to suppose that the only things we can reasonably believe are necessary truths …

People object that being the best available explanation of a fact does not prove something to be true or even probable. Quite so – and again, so what? The explanationist principle – “It is reasonable to believe that the best available explanation of any fact is true” – means that it is reasonable to believe or think true things that have not been shown to be true or probable, more likely true than not.

Alan Musgrave


  1. I agree with Bruce. I think the IBE was intended to get around the impasses created by empiricism (esp. the problem of induction and the problem of unobservables), but in the end it creates its own impasses.

    To re-formulate the IBE slightly to reveal an impasse:

    [1] If hypothesis H is the best available explanation (according to criteria C) of undisputed fact-set S, then it is reasonable to believe H is true.
    [2] H is the best available explanation (according to C) of S.
    [3] Therefore it is reasonable to believe H is true.

    The logical form is fine, but the heavy lifting is done by the content premise [1].

    How does one determine that C delimits ‘best’ and ‘explanation’? Is there currently (has there ever been) a single agreed upon C? If not, then advocacy of this or that hypothesis as ‘the best’ – and the one that reasonable people should believe it true – boils down to a debate over what goes into C and why.

    In economics at least, this is not so much debated as asserted, ipsi dixit. Thereafter, institutional power within the discipline determines C, and thereby (unknowingly or not) determines which hypothesis is given the status ‘Best in Show’.

    • There’s not much that I disagree upon here. IBE is what we actually do as scientists. We cannot deductively infer anything when outside of math and logic. So we have to argue, justify and warrant. That — of course — goes for IBE too. And that’s part of why I’m in favour of IBE — it doesn’t pretend that (empirical) science can be applied logic!
      [For anyone really interested in IBE, Peter Lipton’s book “Inference to the Best Explanation” is a must read.]

  2. The stylized focus on “inference” as an isomorph to deductive reasoning is a strawman. Musgrave seems to enjoy describing how the stuffing may be knocked out and it does not matter. But, he seems unaware of what does matter. One fact does not qualify any explanation of any kind as best. So the form of inference as stated is no part of the process of reasoning justifying belief: it appears to be nothing more than a short form for announcing a conclusion from a process of reasoning and investigation that is to be smugly hidden behind useless cheerleading for a philosophical framework of no particular relevance.
    “Explanation” ??? What qualifies as an explanation in ITTBE? And, what is the nature of the process to construct an explanation? What process do we use to determine what is the “best” explanation? Are explanations compared to one another? What makes one explanation better than another?
    The common use of “explanation” as a word in English designates a wide range of narratives and slogans as explanations. An explanation might reference a person’s motives to explain aberrant behavior or dimly understood laws of physics to, say, explain a tragic accident. One might invoke religious faith in such an explanation as well. Do we sort out which is best?

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