In this article, we continue our exposition of Bas van Fraassen’s constructive empiricism. It ought to be remembered that this doctrine is not merely a philosophy of science, but a philosophy of language, since it specifies how we are to use language in our theory-construction, and what propositions and utterances are to mean within the context of their utterance in the philosophy of science.
One of the common arguments or constructive empiricism is the argument from underdetermination. According to this view, competing theories of empirical observation may make similar predictions about observable phenomena, but differ in their explanation of the underlying root or cause of the phenomena. It is possible that competing explanations of empirical phenomena may be equally plausible, and therefore, there may be no objective standard by which one might accept one over the other(Monton & Mohler, 2014).
Constructive empiricism may be associated with epistemic voluntarism, according to which belief has to do fundamentally with choices or decisions about what the individual chooses to believe. It is because of the incompatibility of the argument from underdertermination with epistemic voluntarism that the constructive empiricist, who is also a voluntarist, ought not appropriate for himself the argument for undetermination(Monton & Mohler, 2014). For the voluntarist, it is okay to believe whatever one wants as long as it does not make one either inconsistent or irrational. This is not the case for those who accept the argument for underdetermination, however. For those who accept the argument from underdetermination, there is no rationality in accepting any scientific thesis, because there is never enough evidence(Monton & Mohler, 2014).
Let us discuss the distinction the constructive empiricist draws between empirical adequacy vs. truth. Just because one believes in the empirical adequacy of a belief, for van Fraassen, does not mean that one must believe in its truth. Such a position depends for its legitimacy on the distinction between the observable and the unobservable. Indeed, it is hard to see what use the distinction between empirical adeqacy vs. empirical truth would have apart from the distinction between the observable vs. the unobservable(Monton & Mohler, 2014).
One of the pragmatic endeavors of the constructive empiricist enterprise is that it does better justice to how actual experimental, scientific or empirical activity gets done than scientific realism does(Monton & Mohler, 2014). For van Fraassen, the purpose of science is to discern regularities in the observable world, and not so much to discern fundamental truths about the structure of the world. The purpose of a theory is not that of the advocate of the correspondence theory of truth, but that of the person who acknowledges that he needs theories to guide his experiments.(Monton & Mohler, 2014)
Van Fraasen’s example of this practice, and its relation to the observable/unobservable distinction, is articulated in terms of Millikan’s “discovery” of the electron. While the realist might see it as a bona fide discovery of an otherwise unobservable entity, van Fraassen sees it as creatively “filling in a value for a quantity which, in the construction of the theory, was so far left open.” For Millikan, the event was the postulation of an unobservable value rather than the discovery of an unobservable entity.
Furthermore, for the constructive empiricist who is trying to describe how science actually works, it is helpful to point out that decisions of theory acceptance have much more to do with pragmatism than with truth. Indeed, for van Fraassen, explanatory value represents a pragmatic virtue rather than an epistemic virtue that has to do with truth. Values such as explanatory power or simplicity or elegance are pragmatic virtues insofar as they contribute to a theory’s empirical adequacy, not their truth. That is, they ought not be regarded as purporting to make statements about the underlying structure of the unobservable world.(Monton & Mohler, 2014)
Empiricists who are scientific realists purport to believe in their theories because they believe the explanatory value implies that they are furnished with theories that accurately represent reality. A false theory, for example, can offer helpful “explanations” of certain phenomena while still being false. “Huygens’s theory explained the diffraction of light, Rutherford’s theory of the atom explained the scattering of alpha particles, Bohr’s theory explained the hydrogen spectrum, Lorentz’s theory explained clock retardation,” but these are all false theories.
For the constructivist, on the contrary, the purpose of scientific investigation is to circumscribe a specific context with the purpose of answering a specific question, rather than to contribute to a holistic theory of everything. Bits of information are related to one another within this specific query. The scientific adequacy of the explantion is relative to the explanatory and pragmatic success of a specific query. For van Fraasen, the emphasis seems to be less a question of a systematic view of reality, and more a question of posing particular questions in particular contexts for pragmatic purposes. One can believe in unobservable entities that explain phenomena, of course, but for van Fraassen, such a tendency, though permissible, is beyond the purview of science.
The concept of counter-factual reasoning is an important element of van Fraasen’s understanding of constructive empiricism. When we engage in causal reasoning, we have frequent recourse to counter-factual reasoning. “If such and such a thing would have happened or not happened, then this other thing would have happened or not happened.” The implicit clause, in such reasoning, according to van Fraassen, is the notion that, all other things being equal, if such and such a condition is met, such and such an effect will result. What is being kept equal, however, varies from one context to another. “Until the context that fixes the ceteris paribus clause is specified, we cannot say what the truth value of the counterfactual in question is. Only once the context is determined does the counterfactual admit of an objective truth value”:
“Van Fraassen points out that any counterfactual has a ceteris paribus clause, but what is “being kept equal” by the asserter of the counterfactual varies from context to context. For example, consider the counterfactual, “If Tom were to light the fuse, there would be an explosion.” If the ceteris paribus clause of the speaker keeps constant the fact that the fuse leads to a barrel of gunpowder, and the fact that lit fuses leading to barrels of gunpowder typically result in explosions, then the counterfactual would, in that context, be true. If, on the other hand, the ceteris paribus clause of the speaker also kept constant the fact that Tom is generally paranoid about explosions around barrels of gunpowder and fuses, and would only light the fuse if he had disconnected the fuse from the barrel, then the counterfactual would, in that context, be false (1980, 116). Until the context that fixes the ceteris paribus clause is specified, we cannot say what the truth value of the counterfactual in question is. Only once the context is determined does the counterfactual admit of an objective truth value”(Monton & Mohler, 2014)
This has important implications for van Fraassen’s understanding of what a law is. Scientific laws themselves have to be understood within the context of context-specific counter-factual reasoning. Thus, the concept of law has a purely pragmatic and context-specific character rather. Scientific laws are not, contrary to the belief of the scientific realist, any sort of real entity in nature.
Monton, Bradley and Mohler, Chad, “Constructive Empiricism”, The Stanford Encyclopedia of Philosophy (Spring 2014 Edition), Edward N. Zalta (ed.), URL = <plato.stanford.edu/archives/spr2014/entries/constructive-empirici….