What is IBE?
Simply, IBE is using logical inference to create a hypothesis that accounts for reliable data, or seeks to explain relevant evidence i.e. the lawn/street etc is wet in the morning, therefore IBE would lead us to hypothesize that it rained last night. IBE also seeks to make the most economic explanation, hence the use of the word ‘best’ in the title.
Kornblith employs IBE to argue from success of science to existence of natural kinds. This raises the question of induction (the success of science can be accounted for by natural kinds, using IBE as the method to make such a hypothesis).
IBE: a form of inference in it’s own right, rather than a form of induction or deduction.
Problems with IBE:
“Within epistemology, IBE is used in at least two ways: as a fundamental rule of belief revision or as a strategy for showing that a favored account of justification has the needed ties to truth.” (p272)
Harman claims that all inductive inference is IBE. IBE as the basic rule of justification is useful for foundationalists. i.e. Moser, for whom foundations are subjective non-conceptual contents, non-propositional experiences that can justify propositions when the propositions are the best explanation for non-conceptual contents. IBE also appeals to truth; just think of Kornblith’s argument for the success of science, or propositions that hold up in comparison with the natural over time.
Van Fraassen sees IBE as worthless. He asserts that it makes us ‘incoherent’:
“… any IBE will work only given some hypotheses to choose from. However, unless we that the relevant contenders probably contain the truth, then inferring to the best explanation does not up the odds that we are picking the true one. Moreover, our current science is just one of many possible accounts of the world, most of which we cannot even state and most of which of course must be false. Thus our own current views must be taken as a random member of the total possible explanations, and thus as probably not true. Thus even if our current theories were the best explanation, that would be no ground for taking them to be true.” (p274)
There is no detailed explanation of IBE by its defenders or detractors. This chapter points out two basic approaches to explanation: unification and causation. If we understand IBE as unification, then 1) IBE collapses into nothing more than coherence with the totality of belief and evidence, thus making IBE redundant and uninformative; or 2) IBE is defeasible, limited argument strategy. If explanation is the citing of causes, then likewise IBE is a defeasible, limited argument strategy.
Day and Kincaid suggest a different form of inference, a kind of precursor to IBE: “On the causal interpretation, IBE traded on our background knowledge about causal processes to warrant an inference to one hypothesis over another. This suggests that IBE does not name a fundamental pattern of inference but that it is instead an instance of another, more general inference strategy. That strategy infers to warranted beliefs from background information and data. When those background beliefs essentially involve claims about explanation and those claims ground inferences from the data to new beliefs, this general inference strategy becomes IBE.” (p282)
“In short, appeals to the best explanation are really implicit appeals to substantive empirical assumptions, not to some privileged form of inference. It is the substantive assumptions that do the real work.” (p282)
IBE is useful, but must be evaluated within a context. In general, context of an argument is everything that goes into determining the adequacy of the inference (except for syntax and semantics); background knowledge, internal vs. external evidence, and purposes. Purpose refers to whether the conclusion is intended to fit into an overall doxastic system. Imagine taking an argument to a fellow specialist, who shares a set of assumptions and background knowledge, vs. to a skeptic.
Internal/external: the most internal standpoint allows only the facts that are to be explained as evidence (in the case of the wet lawn and street, only the wetness is to be used as evidence), whereas the most external standpoint is to ask skeptical questions and find evidence that responds to them (the sense data of the observer is incorrect; Descartes demon).
With contextual factors in mind, it can be seen that depending on the availability of background knowledge, or the presence of a common tradition, IBE the force and success of a given IBE can vary in different contexts.
Is Kornblith using IBE in a contextual way?
Scientific realism suggests we have good evidence that current science is in large part approximately true. IBE is used to draw this conclusion. Anti-realists deny this, and argue that IBE begs the question and that realism is not the best explanation for scientific success.
On anti-realists: “In fact, they need a well-confirmed theory of science. Such a theory would have to explain the rise and fall of scientific theories, the practice of science, and so forth, without invoking realist assumptions. That theory would also have to meet reasonable criteria for good science […] needless to say, anti-realists have no such theory.” (p292)
On realists: “To build successfully an IBE argument for realism, they need (1) to show that anti-realist explanations of science are empirically inadequate and (2) to give a clear account of when scientific success argues for realism. They must achieve the first task to show that realism is the best explanation […] Realists need to take on to take on the second task because we have good evidence that false theories sometimes have been predictively successful.” (p292)
It needs to noted and remembered that this discussion itself must be broken into its own specific contexts. Any theory or argument must be (or will likely be) piecemeal. Science is enormous in its scope and its breadth of claims. A ‘unified’ argument for either realism or anti-realism would be powerful, but unlikely. Any combination of both realist and anti-realist outcomes is possible.