Your complimentary articles

You’ve read all of your complimentary articles for this month. To have complete access to the thousands of philosophy articles on this site, please

If you are a subscriber please sign in to your account.

To buy or renew a subscription please visit the Shop.

If you are a print subscriber you can contact us to create an online account.

Articles

Resolving Hempel’s Raven Paradox

Fred Leavitt reveals how the whiteness of swans proves the blackness of ravens.

Many scientific theories and laws are of the form “All A is B.” Two examples are “Water at sea level boils at 100 degrees centigrade” and “Schizophrenia is associated with an excess of dopamine in the limbic system.” But philosopher and logician Carl Hempel pointed out a seeming paradox (Hempel, 1945). As virtually all logicians agree, the propositions “All ravens are black” and “All nonblack things are nonravens” are equivalent. To test the former, a scientist would look for ravens and check their colour.

…