Underdetermination as an Underdetermination as an Epistemological Test Tube: Epistemological Test Tube: Expounding Hidden Values Expounding Hidden Values of the Scientific Community of the Scientific Community

Martin Carrier (Bielefeld University) Martin Carrier (Bielefeld University)

1. Introduction

Underdetermination thesis: any given set of data can always be represented by different, conceptually incompatible accounts. Claim: underdetermination plays a fruitful role in epistemology by pinpointing the impact of non-empirical virtues or cognitive values on theory choice.

=> Underdetermination contributes to illuminating what scientific rationality actually is.

Duhem-Quine underdetermination brings to light the non-empirical epistemic commitments which prevail in the scientific community and which form an indis-pensible part of our understanding of scientific knowledge.

3. Duhem’s Master Argument for Underdetermination

Duhem: Confirmation and refutation of particular hypotheses cannot be grounded on logic and experience alone.

Hypothetico-deductive confirmation: The same observational consequences may equally follow from a different hypothesis incompatible with the first.

Example from geocentric astronomy: Eccenter hypothesis and epicycle hypothesis as two empiri-cally equivalent accounts of annual solar motion. Hypothetico-deductive refutation: no hypothesis can be refuted by relying on logic and experience only. An anomalous observation merely demonstrates that at least one of the assumptions brought to bear in the test procedure is mistaken.

Principle of the uniformity of celestial motions.Apparently non-uniform annual motion of the sun: The two constructions saved the uniformity principle at the expense of adjusting other assumptions.

Duhem’s conclusion:Theories are creations of the human mind and never lose their dependence on human imagination.

Nature always leaves room for alternative accounts. Neither proofs nor refutations are part of scientific method.

4. Duhem, Quine, and Beyond: The Career of Underdetermination

Duhemian characteristics of underdetermination: • Reference to real-life theories, not to artificially contrived toy models.• The possibility of alternative accounts is stressed but no recipe for actually constructing them is provided. • Underdetermination is confined to a given range of phenomena.

=> Duhem had temporary indistinguishability in mind.

Temporary underdetermination plays an important epistemological role: it serves to illuminate the bearing of non-empirical virtues in judging hypoth-eses and adopting theories.

Duhem-Quine underdetermination: Confirmational version: any given set of data can always be represented by different, conceptually incompatible accounts. Refutational variant: arbitrary hypotheses can be maintained in the face of arbitrary evidence if one is prepared to adjust the system of beliefs, maybe profoundly, in other respects.

Discussion of underdetermination in the second half of the 20th century: articulation of the thesis.

Standard scenarios: — Distinction between the observed and the unob- served behavior of entities.Rejected with reference to the goal of conceptual parsimony — “Deoccamization”: supplanting a theoretical quantity of a theory by a fixed combination of several other quantities none of which has separate empirical bearing.

=> Underdetermination as a proven theorem. But the rephrased versions are completely depend-ent conceptually on their respective originals.

Critics: The underdetermination thesis is either trivial or false. Underdetermination only obtains in general if no con-straints of plausibility are placed on the necessary adjustment strategies.

Quine’s version of the underdetermination thesis licenses recourse to what the critics would call “trivial revisions.”

Nevertheless, the underdetermination thesis serves a non-trivial epistemological function.

5. In Defense of Duhem-Quine Under- determination

Duhem-Quine underdetermination can be construed as a positive claim about options left to scientific theorizing by experience. Empirically equivalent alternatives: no experience-based superiority. Yet the scientific community makes a choice in such cases. Scientists quite unanimously vote against nomo-logical splits and deoccamized theories.

=> These choices are necessarily guided by non-empirical virtues—in this cases “conceptual parsimony.”

Non-empirical values which are usually operative in a hidden or implicit way are laid open in the choice between empirically equivalent alternatives.

Underdetermination provides us with an opportu-nity to elucidate in which sense the preferred accounts are superior.

Duhem-type examples: competing real-life accounts that were indistinguishable in empirical respect.

Struggle between Ptolemaic geocentrism, Coperni-can heliocentrism and Tychonic geoheliocentrism in late 16th century astronomy. All three accounts yielded the planetary motions with roughly the same accuracy.

Yet Copernican astronomy excelled in explanatory power as regards the qualitative features of planetary motion. Geocentric astronomy outperformed its Copernican rival regarding its coherence with the accepted Aristotelian physics.

The Tychonic compromise system preserved the explanatory achievements of the Copernican approach and remained in agreement with most of the received physics and cosmology

=> (1) The scientific community did make a choice between empirically equivalent alternatives and (2) the criteria operative in this choice were explanatory power and coherence with back- ground knowledge.

Conventionality of physical geometry: alternative space-time structures that are compatible with the same set of spatiotemporal measurements.

Alternative accounts required the introduction of force fields for which no sources could be identified.

Universal dismissal of these non-standard alterna-tives by invoking the non-empirical criterion of the preservation of causality.

Quantum mechanics: The picture behind Bohm’s theory is at variance with standard quantum mechanics, but the two are indistinguishable in observational respect. “Testability” militates against Bohm’s theory.

The historical fact is that the scientific community does not rest undecided, wavering helplessly be-tween different Duhem-Quine options. They rather pick an account.

Theory choice goes beyond the austere hypothetico-deductivist framework and bears witness to the influence of non-empirical virtues.

6. Platonism and Aristotelianism as Divergent Approaches to Nature

Model debate: The details of the phenomena typically escape the grip of comprehensive theory.

However, the conceptual structure of the models used for coping with the phenomena is typically still shaped by general theory.

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“Orifice problem” in hydrodynamics: amount of liquid that streams out of a circular hole in a tank.

Received treatment by invoking the conservation of mechanical energy. But in fact, the flow is considerably smaller. Correction factor that varies with the profile of the opening and is assessed empirically.

Possibility of replacing the combination of theoreti-cal derivation and empirical adjustment by a phenomenological approach which connects directly the measured rates for various tanks and openings.

A phenomenological approach and a theory-shaped approach can easily come out empirically equivalent and the preference for one of them is based on heuristic reasons.

The two approaches exemplify divergent attitudes toward nature: Platonism is committed to the rule of law; the uni-versal is supposed to pervade the whole of nature.Aristotelianism insists on the basic character of specific cases.

=> The preference within the scientific community for the theory-centered approach is not dictated by nature.

7. The Invisibility of Underdetermination

Underdetermination is denied by many scientists and philosophers of science: it is difficult enough to identify one account that is in accordance with the phenomena; thinking up an alternative is often impossible.

Whereas the freedom of choice has been over-estimated by some philosophers and sociologists of science, it has been underrated by many scientists.

Relevant arguments often invoke substantive principles and methodological commitments; they include the non-empirical values that Duhem-Quine underdetermination places in the limelight.

8. Conclusion

The underdetermination thesis establishes a leeway for science when faced with the verdict of nature.

The reason for the significance of this leeway is that the criteria appealed to in picking an account from the collection of empirically admissible options bear wit-ness to our epistemological intuitions.

The pertinent non-empirical criteria uncover the features of experience we consider worth knowing. Epistemic values are constitutive of what we under-stand by scientific knowledge.

They are the basis of normative judgments about the adequacy of assessments within science.