According to Nicod's criterion of confirmation, a hypothesis of the form ‘All P are Q’ is confirmed by its positive instances, i.e. by entities that are P and Q. It is well known, however, that the criterion gives origin to counterintuitive results. For example, it sanctions the confirmation of ‘All nonblacks are nonravens’ by a nonblack nonraven. Since this hypothesis is logically equivalent to ‘All ravens are black,’ it follows that the criterion indirectly sanctions the counterintuitive confirmation of ‘All ravens (...) are black’ by a non black nonraven, e.g. by a white shoe. (shrink)

Good chefs know the importance of maintaining sharp knives in the kitchen. What’s their secret? A well-worn Taoist allegory offers some advice. The king asks about his butcher’s impressive knifework. “Ordinary butchers,” he replied “hack their way through the animal. Thus their knife always needs sharpening. My father taught me the Taoist way. I merely lay the knife by the natural openings and let it find its own way through. Thus it never needs sharpening” (Kahn 1995, vii; see also Watson (...) 2003, 46). Plato famously employed this image as an analogy for the reality of his Forms (Phaedrus, 265e). Just like an animal, the world comes pre-divided for us. Ideally, our best theories will be those which “carve nature at its joints”. While Plato employed the “carving” metaphor to convey his views about the reality of his celebrated Forms, its most common contemporary use involves the success of science -- particularly, its success in identifying distinct kinds of things. Scientists often report discovering new kinds of things -- a new species of mammal or novel kind of fundamental particle, for example -- or uncovering more information about already familiar kinds. Moreover, we often notice considerable overlap in different approaches to classification. As Ernst Mayr put it: No naturalist would question the reality of the species he may find in his garden, whether it is a catbird, chickadee, robin, or starling. And the same is true for trees or flowering plants. Species at a given locality are almost invariably separated from each other by a distinct gap. Nothing convinced me so fully of the reality of species as the observation . . . that the Stone Age natives in the mountains of New Guinea recognize as species exactly the same entities of nature as a western scientist. (Mayr 1987, 146) Such agreement is certainly suggestive. It suggests that taxonomies are discoveries rather than mere inventions. Couple this with their utility in scientific inference and explanation and we have compelling reason for accepting the objective, independent reality of many different natural kinds of things.. (shrink)

Many solutions of the Goodman paradox have been proposed but so far no agreement has been reached about which is the correct solution. However, I will not contribute here to the discussion with a new solution. Rather, I will argue that a solution has been in front of us for more than two hundred years because a careful reading of Hume's account of inductive inferences shows that, contrary to Goodman's opinion, it embodies a correct solution of the paradox. Moreover, the (...) account even includes a correct answer to Mill's question of why in some cases a single instance is sufficient for a complete induction, since Hume gives a well-supported explanation of this reliability phenomenon. The discussion also suggests that Bayesian theory by itself cannot explain this phenomenon. Finally, we will see that Hume's explanation of the reliability phenomenon is surprisingly similar to the explanation given lately by a number of naturalistic philosophers in their discussion of the Goodman paradox. (shrink)