Maxwell: Against Empiricism

1. Maxwell: Against Empiricism Kareem Khalifa Department of Philosophy Middlebury College

2. Overview • Background • Maxwell on the observable-unobservable distinction

3. I.A. Maxwell’s main line of attack • If antirealism is true, then there must be a clear distinction between observable and unobservable entities. • There is no clear distinction between observable and unobservable entities. • Therefore, antirealism is false.

4. I. B. Four kinds of antirealism • Fictionalism • Instrumentalism • Phenomenalism • Eliminativism

5. 1. Fictionalism • Fictionalism: Beliefs about unobservable entities are merely useful fictions. • They are psychological crutches that help guide scientists in devising experiments, but they need not be true or even meaningful in order to fulfill this function.

6. 2. Instrumentalism • Commitments to unobservable entities are tools for organizing, predicting, and controlling observable entities. As a result, they’re practical commitments, not beliefs. • Compare: hammers don’t mean anything; they’re used for certain things.

7. 3. Phenomenalism • Sentences about unobservable entities are reducible to sentences about observable entities. • Ex. “Here are quarks” is reducible to statements about (energy level) E and (angle) , etc. • “Here is a table” is reducible to statements about “Something brown appears to me,”“Something seems firm to my touch,” etc.

8. 4. Eliminativism • Unobservable entities should be removed from our vocabulary, primarily because there would be no loss in doing so.

9. Maxwell’s main line of attack ✔ • If antirealism is true, then there must be a clear distinction between observable and unobservable entities. • There is no clear distinction between observable and unobservable entities. • Therefore, antirealism is false.

10. II. Maxwell’s challenge • All of these antirealisms depend on an observable-unobservable distinction. • But what is unobservable today may be observable at a later time, given technological advances, etc. • So none of these antirealisms are tenable.

11. A. Three notions of observability • Something is observable iff it is expressible as a sense-data report. • Something is unobservable iff the theory positing it, plus a theory of perception, entails that it is unobservable. • Something is observable iff a human, unaided by technology, could observe it.

12. Sense-data approach • Something is observable iff it is expressible as a sense-data report. • Sense data reports are statements about experiencing basic observable properties. Thus, “It appears to me that something red is here now” would be a sense-data report.

13. Maxwell’s rebuttals to the sense-data approach • If this is right, then ordinary physical objects are theoretical (unobservable). • That seems absurd! • The authority of sense-data reports rests on the authority of statements about ordinary physical objects. • So, the latter can’t be derivative of the former.

14. More on Rebuttal C • There are “quickly decidable statements,” i.e., statements of which ordinary people can ascertain the truth/falsity with little controversy and difficulty. (1060) • Sentences about physical objects are quickly decidable, and sense data appear to be theoretical terms that explain these quickly decidable sentences. • Thus the reason we believe in sense data is because they explain quickly decidable statements.

15. Example Because something appears red to me now. I see an apple. Why do you think that you see an apple?

16. Furthermore… • We can train ourselves to directly observe these theoretical entities—sense data. • So why can’t we train ourselves to directly observe other theoretical entities (e.g., gravitational fields)?

17. The theory approach • Something is unobservable iff the theory positing it, plus a theory of perception, entails that it is unobservable. (1057) • Ex. Electrons, quarks

18. Maxwell’s rebuttals to the theory approach • This is inconsistent with fictionalism and instrumentalism. • The statement “X is unobservable” would have to be meaningful. • Our theory of perception might be wrong or only right at time t. • “The mutation objection”

19. Rebuttal D: fictionalism, instrumentalism, & the theory approach • Theory Approach: Something is unobservable iff the theory positing it, plus a theory of perception, entails that it is unobservable. • Theories only entail meaningful statements. • Fictionalism & instrumentalism deny that statements about unobservables are meaningful. • So fictionalism, instrumentalism and the theory approach are incompatible.

20. Rebuttal E: The mutation objection • Recall: Something is unobservable iff the theory positing it, plus a theory of perception, entails that it is unobservable. • But our theory of perception is a theory of human perception, and this is somewhat arbitrary.

21. The unaided human account • Something is observable iff a human, unaided by technology, could observe it. • Thus, there is no way of inferring that something observed through a microscope, telescope, etc. is a physical object. • They are only color patches, shadows, etc.

22. Do you see a subatomic particle?

23. Maxwell’s rebuttals to the unaided human account • Every observation is mediated through something, so nothing would be observable if this response were true. • The mediation objection • The argument from contemporary chemistry. • Modern chemistry poses no strong distinction between observable and unobservable molecules.

24. The mediation objection • If the unaided human account is true, then we can’t legitimately infer the existence of physical objects from observations involving: • Any sensory aid whatsoever—opera glasses, bifocals, etc. • Any medium whatsoever—seeing through atmospheric conditions, windowpanes, etc. • These inferences are legitimate. • So the unaided human account is false. Thus, there is no firm distinction between theory and observation—we clearly need a theory of optics to treat anything we see as a “direct observation.” (1056)

25. Contemporary chemistry • There is a continuous transition from small “unobservable” molecules such as hydrogen, to “medium-sized” ones (proteins), to large, directly observable ones (salt crystals). • Thus molecules are neither clearly observable nor clearly unobservable entities.

27. Recap • Antirealism requires a strong distinction between observable and unobservable entities. • Three of its best attempts—the sense-data, theory, and unaided human approaches—all face serious objections.