It is argued that neither the "theory-informity" of observations nor the Quine-Duhem thesis pose any in principle threat to the objectivity of theory evaluation. The employment of exploratory theories does not generate incommensurability, but on the contrary is responsible for the mensurability and commensurability of explanatory theories, since exploratory theories enable scientists to make observations which are critical in the evaluation of explanatory theories. The employment of exploratory theories and other auxiliary hypotheses does not enable a theory to always accommodate (...) recalcitrant observations to preserve evidential equivalence with a rival theory. Explanatory theories become rapidly degenerating if exploratory theories or other auxiliary hypotheses which inform the original confirmation base are modified to accommodate recalcitrant observations. (shrink)

SummaryThe conspicuous role of taxonomy and debates about taxonomy in the well‐established physical science of pedology throws into question the Popperian rejection of definition and classification.

Essentialism--understood as the doctrine that there are natural kinds--can be sustained with respect to the most fundamental physical entities of the world, as I elsewhere argue. In this paper I take up the question of the existence of natural kinds among complex structures built out of these elementary ones. I consider a number of objections to essentialism, in particular Locke's puzzle about the existence of borderline cases. A number of recent attempts to justify biological taxonomy are critically examined. I conclude (...) that theory partially justifies such taxonomies but supports only a weaker form of essentialism. (shrink)

A series of explanatory hypotheses are examined under the assumption that the logical structure of function attributions is dependent on the methodological constraints which these hypotheses conform to. Two theses are argued for: (1) Given these methodological constraints, if something has the function of doing Y, then normally it is the only kind of thing that can do Y in that kind of system. (2) What distinguishes function attributions from causal attribution is not that function attributions explain the etiology of (...) the causally efficacious object, as Wright has suggested. The distinction lies rather in that the object's having the effect, which is attributed to it as its function, must figure in the explanation of why it does what it does to achieve that effect. (shrink)