The Duhem-Quine Problem


Submitted for an M Sc

In History and Philosophy of Science

At the University of Sydney


Supervised by Alan Chalmers


Since the time of the Royal Society in the seventeenth century science has depended heavily on an empirical base of observed evidence or 'matters of fact'.  Thus in Western science, empiricism in some form or other has for the most part claimed the field from magical/mystical, traditional or  rationalist/intellectualist epistemologies.

A strong form of empiricism  sought for positively justified or certain foundations of belief,  by way of inductive proof derived from observations.  This line of thought was harshly treated by Hume's critique of induction, a critique revived in modern times by Duhem and Popper.  The logic of the situation is that repeated observations of white swans do not preclude the possibility of the existence of black swans.

The philosophy of science appeared to circumvent the problem of justification by shifting its aim to progress and the growth of knowledge.  This revised aim calls for the formation of critical preferences between rival theories, in the light of evidence and arguments available at the time. Thus preferences can shift as the new evidence or arguments arise. In this context the logic of falsification (the modus tollens) appeared to provide an empirical base of a kind, albeit a critical kind, capable of error identification if not verification.  The observation of a single black swan refutes the general proposition that all swans are white.

The high point of falsification is the crucial experiment, which may be performed if two rival hypotheses predict different consequences in some concrete situation.  When that situation comes about, whether by experimental manipulation or by the fortunate conjunction of some natural phenomena, then the result may in principle decide one way or the other between the competitors. 

The Duhem-Quine thesis casts doubt on the logic of falsification and thus on the decisive character of the crucial experiment.  Duhem pointed out that the outcome of an experiment is not predicted on the basis of one hypothesis alone because auxiliary hypotheses are involved as well.  These are not usually regarded as problematic, and they are not generally perceived to be under threat when the hypothesis of interest is tested.  However, if the outcome of the test is not that predicted, it is logically possible that the hypothesis under test is sound and the error lies in one or more of the auxiliaries.

These  considerations destroy the logically decisive character of the crucial experiment.  The outcome of such an experiment is supposed to provide support for one hypothesis by demonstrating the falsity of its rival.  But, as was the case with a possible falsification, the rival cannot be so easily put aside if the defect conceivably lies elsewhere in the complex of hypothesis used to predict the effect.  The Duhem-Quine problem  raises the question "Can theories be refuted?".

The problem which Duhem identified at the turn of the century did not make a great impact for some time due to the long-running obsession in the philosophy of science with the problems of induction and demarcation.   It assumed a new lease of life as the Duhem-Quine problem following a challenging paper by Quine, published in 1953.  Subsequently a considerable volume of literature has accumulated, augmented by something of a revival of interest in Duhem's contribution generally.

The problem, as it is widely understood, has attracted the attention of the strong program in the sociology of science, also of the resurgent Bayesians.  An especially interesting contribution to the debate comes from the 'new experimentalism' and it has been suggested that this has rendered irrelevant many of the concerns of traditional philosophy of  science, among them the Duhem-Quine problem.

This thesis will examine various responses to the Duhem-Quine problem, the rejoinder from Popper and the neo-Popperians, the Bayesians and the new experimentalists.  It will also describe Duhem's own treatment of hypothesis testing and selection, a topic which has received remarkably little attention in view of the amount of literature on the problem that he supposedly revealed.