Academic journal article Analysis and Metaphysics

Why Van Fraassen Should Amend His Position on Instrument-Mediated Detections

Academic journal article Analysis and Metaphysics

Why Van Fraassen Should Amend His Position on Instrument-Mediated Detections

Article excerpt

1.Introduction: The Relevance of an Adequate Characterization of Observability (for Constructive Empiricism)

According to Bas van Fraassen's constructive empiricism, if one accepts science, then she is ready to believe what its theories say about the observable parts of the world as true, while the rest needs no matter (see van Fraassen, 2005: 111).

What van Fraassen means by "observable" has been an object of debate over the last decades, but there exists a simple way of disposing of the matter, by saying that we can use whichever meaning of the word we want "and go from there." As if whether there is something wrong with van Fraassen's characterization of "observable" or not were irrelevant for his view of science.

If we adopt voluntarism as our epistemological framework, this might apparently be the case. Within voluntarist epistemology, issues of justification do not arise and one's set of beliefs just needs to show logical consistency and probabilistic coherence in order not to be considered irrational (see Dicken, 2010: 27-28). Arguably, then, in such a perspective constructive empiricism is safe, as long as it meets the criteria just mentioned (which it does) - and van Fraassen's exact definition or use of the adjective "observable" is of no impact.

Again, we might not agree with his characterization of "observable" - and judge that he should rather use the adjective "frassable" -, because observability is something different from what he thinks it is. But this is not relevant. Suppose the correct way to put it were that, according to constructive empiricism, what the theories say about the frassable parts of the world is true, while the rest needs no matter. Van Fraassen's view of science would still remain a respectable position in philosophy.

But is that so?

Imagine that one, let's call her Fras, defines "observable" as meaning "perceived while standing barefoot." She might argue that, if one wants to know the limits of observability, it is better to ask scientists and not philosophers and maintain that the aim of science is to give us theories that are true with respect to the entities that can in principle be perceived while standing barefoot. In a voluntarist framework, if Fras' set of beliefs shows logical consistency and probabilistic coherence then it cannot be considered irrational. Can Fras also hope her view of science will be judged as respectable? Perhaps not. Fras' definition of "observable" is probably doomed to be held as not having much relevance for scientific practice, although coherent and meaningful, just as happens with van Fraassen's notion of observability (see Chang, 2004: 85). The same goes for her position on science and its aim, which of course rests on her peculiar characterization of observability.

What about constructive empiricism, then?

Considering "observable" as meaning "perceptible in principle without the aid of instruments" might appear peculiar too. The point however, some might say, is not van Fraassen's characterization of observability, but rather whether he has reasons for the distinguished position that, in his view, the entities which satisfy the rough guide of "observable" he proposed in The Scientific Image have (see 1980: 16). Again, one might answer that van Fraassen does not need to present any reason, as issues of justification do not arise in a voluntarist framework. But this would mean that constructive empiricism could in fact adopt whichever meaning of "observable" one has in mind, as said before, provided it did not jeopardize its coherence.

Van Fraassen somehow acknowledges the possibility of adopting an acception of "observable" as different from the one he uses within constructive empiricism (see 2008: 110). But, despite being a voluntarist in epistemology, he is not worried with the mere internal coherence of constructive empiricism. Answering to Alspector-Kelly, in "Constructive Empiricism and Modal Nominalism" (2003), Monton and van Fraassen reminded him (and the readers) that constructive empiricism is above all a doctrine about the aim of science. …

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