The jargon is of course of medieval origin, but the term ‘haecceitism’ was introduced into contemporary discussions of modal metaphysics by David Kaplan. He characterized the doctrine in highly metaphorical terms, but the basic idea of his way of drawing the distinction was that the haecceitist allows, while the anti-haecceitist rejects, the reducible identification of individuals across possible worlds. According to Kaplan's anti-haecceitist, individuals in different possible worlds may be “clothed in attributes which cause them to resemble one another closely. But there is no metaphysical reality of sameness or difference which underlies the clothes.” The haecceitist, in contrast, holds that for individuals in different possible worlds, “a common ‘thisness’ may underlie extreme dissimilarity or distinct thisness may underlie great resemblance.”

the resistance of bacteria to certain antibiotics

Despite his eloquent praise of the gentlemanly qualities of the highwayman, Ainsworth's robber is more coarse-grained than Bulwer's Paul Clifford. In the best traditions of the ideal knight of the road, he is loath to hurt or kill anyone—but he reserves the right to do so in self-defence.

But, that instead of the emulation or competition being for the mere acquisition of individual money or property, it would be that noble and generous emulation—to excel in the useful arts, the sciences, literatuer and moral excellence.