 \(\alpha_1\) simply specifies that no object is both white and black, while \(\alpha_2\) says that, if there are swans at all, then there also is some black swan. Also posit, again, \(e = swan(a) \wedge white(a)\). Under \(\alpha_1\) and \(\alpha_2\), the observation of a white swan clearly disconfirms (indeed, refutes) the hypothesis \(h\) that all swans are white. Hempel’s theory (extended) faces difficulties here, because for \(k = dev_{e}(\alpha_1 \wedge \alpha_2)\) it turns out that \(e\wedge k\) is inconsistent. But HD-confirmation gets this case right, thus capturing appropriate boundary conditions for Nicod’s generally sensible claims. For, with \(k = \alpha_1 \wedge \alpha_2\), one has that \(h\wedge k\) is consistent and entails \(\neg e\) (for it entails that no swan exists), so that \(e\) HD-disconfirms (refutes) \(h\) relative to \(k\) (see Good 1967 for another famous counterexample to Nicod’s condition).