Maxwell: Against Empiricism Kareem Khalifa Department of Philosophy Middlebury College

Overview I. Background II. Maxwell on the observable- unobservable distinction

I.A. Maxwell’s main line of attack 1. If antirealism is true, then there must be a clear distinction between observable and unobservable entities. 2. There is no clear distinction between observable and unobservable entities. 3. Therefore, antirealism is false.

I. B. Four kinds of antirealism 1. Fictionalism 2. Instrumentalism 3. Phenomenalism 4. Eliminativism

1. Fictionalism Fictionalism: Beliefs about unobservable entities are merely useful fictions. 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.

2. Instrumentalism Commitments to unobservable entities are tools for organizing, predicting, and controlling observable entities. As a result, they’re practical commitments, not beliefs. 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.

3. Phenomenalism Sentences about unobservable entities are reducible to sentences about observable entities. 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.

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

Maxwell’s main line of attack 1. I f antirealism is true, then there must be a clear distinction between observable and unobservable entities. 2. T here is no clear distinction between observable and unobservable entities. 3. T herefore, antirealism is false. ✔

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

A. Three notions of observability 1. Something is observable iff it is expressible as a sense-data report. 2. Something is unobservable iff the theory positing it, plus a theory of perception, entails that it is unobservable. 3. Something is observable iff a human, unaided by technology, could observe it.

Sense-data approach Something is observable iff it is expressible as a sense-data report. 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. 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.

Maxwell’s rebuttals to the sense-data approach B. If this is right, then ordinary physical objects are theoretical (unobservable). –That seems absurd! C. 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.

More on Rebuttal C 1. There are “quickly decidable statements,” i.e., statements of which ordinary people can ascertain the truth/falsity with little controversy and difficulty. (1060) 2. Sentences about physical objects are quickly decidable, and sense data appear to be theoretical terms that explain these quickly decidable sentences. 3. Thus the reason we believe in sense data is because they explain quickly decidable statements.

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

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

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

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

Rebuttal D: fictionalism, instrumentalism, & the theory approach 1. Theory Approach: Something is unobservable iff the theory positing it, plus a theory of perception, entails that it is unobservable. 2. Theories only entail meaningful statements. 3. Fictionalism & instrumentalism deny that statements about unobservables are meaningful. So fictionalism, instrumentalism and the theory approach are incompatible. So fictionalism, instrumentalism and the theory approach are incompatible.

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

The unaided human account Something is observable iff a human, unaided by technology, could observe it. 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. 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.

Do you see a subatomic particle?

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

The mediation objection 1. 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. 2. These inferences are legitimate. 3. 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)

Contemporary chemistry 1. There is a continuous transition from small “unobservable” molecules such as hydrogen, to “medium-sized” ones (proteins), to large, directly observable ones (salt crystals). 2. Thus molecules are neither clearly observable nor clearly unobservable entities.

Hydrogen Atom Protein Salt Crystal

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