Scientific realism and inference to the best explanation

15 Jan, 2022 at 16:28 | Posted in Theory of Science & Methodology | 2 Comments

In inference to the best explanation we start with a body of (purported) data/facts/evidence and search for explanations that can account for these data/facts/evidence. Having the best explanation means that you, given the context-dependent background assumptions, have a satisfactory explanation that can explain the fact/evidence better than any other competing explanation — and so it is reasonable to consider/believe the hypothesis to be true. Even if we (inevitably) do not have deductive certainty, our reasoning gives us a license to consider our belief in the hypothesis as reasonable.

Accepting a hypothesis means that you believe it does explain the available evidence better than any other competing hypothesis. Knowing that we — after having earnestly considered and analysed the other available potential explanations — have been able to eliminate the competing potential explanations, warrants and enhances the confidence we have that our preferred explanation is the best explanation, i. e., the explanation that provides us (given it is true) with the greatest understanding.

This, of course, does not in any way mean that we cannot be wrong. Of course we can. Inferences to the best explanation are fallible inferences — since the premises do not logically entail the conclusion — so from a logical point of view, inference to the best explanation is a weak mode of inference. But if the arguments put forward are strong enough, they can be warranted and give us justified true belief, and hence, knowledge, even though they are fallible inferences. As scientists we sometimes — much like Sherlock Holmes and other detectives that use inference to the best explanation reasoning — experience disillusion. We thought that we had reached a strong conclusion by ruling out the alternatives in the set of contrasting explanations. But — what we thought was true turned out to be false.

That does not necessarily mean that we had no good reasons for believing what we believed. If we cannot live with that contingency and uncertainty, well, then we are in the wrong business. If it is deductive certainty you are after, rather than the ampliative and defeasible reasoning in inference to the best explanation — well, then get in to math or logic, not science.

What exactly is the inference in ‘inference to the best explanation’, what are the premises, and what the conclusion? …

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 …

alan musgravePeople 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

2 Comments

  1. Lars in this blog:
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    《 If it is deductive certainty you are after, rather than the ampliative and defeasible reasoning in inference to the best explanation — well, then get in to math or logic, not science.》
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    Lars in “The fatal flaw of mathematcs”, about two months ago:
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    《When not even being able to fulfil the dream of a complete and consistent axiomatic foundation for mathematics […]》
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    So is deductive certainty even possible in math or logic? Or does explosion make trivialism perfectly valid?
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    Lars in this blog, quoting Alan Musgrave:
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    《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.》
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    How far do you go to enforce your fundamentally uncertain explanations? Are you 100% certain full employment and price stability should be public policy goals, in agreement with the mainstream? Is true heterodoxy advocating for an inflation-proofed basic income?
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    Lars quotes Galbraith in a subsequent blog, “Cambridge economics has died out”:
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    《Markets were not treated as if they were magical. It was obvious that most resources and components did not move under the influence of an invisible hand. Rather, they moved according to contracts between companies on terms set by negotiation》
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    Does this mean inflation is a power play, effectively neutralized through full indexation?

  2. One thing I’m not sure about “Bayesian” thinking about probability is equating conditioning with the occurrence of future events. In probability theory, we look at random experiments from the pre-factual perspective. We do not condition on event that will occur outside of the random experiment which is defined by the probability space. So, ‘the priors’ are either defined by the joint distribution, or they are idle musing.


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