Theory And Observation The Duhem Quine Thesis Notes

The Duhem-Quine Thesis

The Aim and Structure of Physical Theory – Duhem

• Instrumentalist: “The sole purpose of physical theory is to provide a representation and classification of experimental laws; the only test permitting us to judge a physical theory and pronounce it good or bad is the comparison between the consequences of this theory and the experimental laws it has to represent and classify.”

• “[I]n the mind of the physicist there are constantly present two sorts of apparatus: one is the concrete apparatus in glass and metal, manipulated by him, the other is the schematic and abstract apparatus which theory substitutes for the concrete apparatus and on which the physicist does his reasoning.”

• “[T]he physicist can never subject an isolated hypothesis to experimental test, but only a whole group of hypotheses; when the experiment is in disagreement with his predictions, what he learns is that at least one of the hypotheses constituting this group is unacceptable and ought to be modified; but the experiment does not designate which one should be changed.”

• “We recognize a correct principle by the facility with which it straightens out the complicated difficulties into which the use of erroneous principles brought us.”

• There is “no absolute principle” concerning when a hypothesis ought to be abandoned in the face of evidence.

‘Two Dogmas of Empiricism’ – Quine

• The two dogmas:

1. Belief in a fundamental cleavage between truths which are analytic, or grounded in meanings independently of matters of fact, and truths which are synthetic, or grounded in fact.

2. Reductionism: the belief that each meaningful statement is equivalent to some logical construct upon terms which refer to immediate experience.

• You can’t get a good definition for analyticity. First: “the notion of self-contradictoriness, in the quite broad sense needed for this definition of analyticity, stands in exactly the same need of clarification as does the notion of analyticity itself. The two notions are the two sides of a single dubious coin.”

• Second attempt would be to follow Kant and say that a statement is analytic when it’s true by virtue of meanings and independently of fact.

  • But: “Once the theory of meaning is sharply separated from the theory of reference, it is a short step to recognizing as the primary business of the theory of meaning simply the synonymy of linguistic forms and the analyticity of statements; meanings themselves, as obscure intermediary entities, may well be abandoned.”

    • So we have the problem of analyticity again.

• Carnap tried to explain analyticity by appeal to ‘state-descriptions’ (an exhaustive assignment of truth values to the atomic statements of the language) > a statement is analytic when it comes out true under every state description.

  • BUT this only works for languages devoid of extralogical synonym pairs such as ‘bachelor’ and ‘unmarried man’.

  • “The criterion in terms of state-descriptions is a reconstruction at best of logical truth, not of analyticity.”

• “A natural suggestion, deserving close examination, is that the synonymy of two linguistic forms consists simply in their interchangeability in all contexts without change of truth value.”

• “Interchangeability salva veritate is meaningless until relativized to a language whose extent is specified in relevant respects.”

• In an extensional language, interchangeability salva veritate is no assurance of cognitive synonymy of the desired type.

• “There is no assurance here that the extensional agreement of ‘bachelor’ and ‘unmarried man’ rests on meaning rather than merely on accidental matters of fact, as does the extensional agreement of ‘creature with a heart’ and ‘creature with kidneys’.”

• So it’s probably going to be hard to explain analyticity by appeal to cognitive synonymy.

• “Analyticity at first seemed most naturally definable by appeal to a realm of meanings. On refinement, the appeal to meanings gave way to an appeal to synonymy or definition. But definition turned out to be a will-o’-the-wisp, and synonymy turned out to be best understood only by dint of a prior appeal to analyticity itself. So we are back at the problem of analyticity.”

• On the 2^nd dogma: “our statements about the external world face the tribunal of sense experience not individually but only as a corporate body.”

• Link between two dogmas: “[A]s long as it is taken to be significant in general to speak of the confirmation and infirmation of a statement, it seems significant to speak also of a limiting kind of statement which is vacuously confirmed, ipso facto, come what may; and such a statement is analytic.” So they’re basically one and the same dogma.

• “[T]he total field is so underdetermined by its boundary conditions, experience, that there is much latitude of choice as to what statements to reevaluate in the light of any single contrary experience.”

• “No particular experiences are linked with any particular statements in the interior of the field, except indirectly through considerations of equilibrium affecting the field as a whole.”

• Then, “it is misleading to speak of the empirical content of an individual statement.”

• “[I]t becomes folly to seek a boundary between synthetic statements, which hold contingently on experience, and analytic statements, which hold come what may.”

  • “Any statement can be held true come what may, if we make drastic enough adjustments elsewhere in the system.”

• The difference is “one of degree” and “turns upon our vaguely pragmatic inclination to adjust one strand of the fabric of science rather than another in accommodating some particular recalcitrant experience.”

Commentary on DQ-thesis – Curd & Cover (eds.)

• A schema for Duhem’s thesis of holism (NB possibly too strong??):

  • D1: (TO₁), and

  • D2: (T&A₁&A₂&…&A_n)O₁

• And for his minimal thesis about the ambiguity of falsification:

  • D3: (O₁T), and

  • D4: O₁ (T&A₁&A₂&…&A_n)

  • Remember to define variables etc.

• Does not imply anything about the...

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