 Note, however, that the most general prudential end—something like surviving, say—may be thought to have an equal claim to the title of a “necessary” end: it is set for us by our nature as living members of a species that has evolved through natural selection. And so by the same logic it might be taken to underwrite a categorical—albeit still prudential—norm of belief, especially in life-or-death cases such as that of the cancer diagnosis above.