AIDS presents difficult and unprecedented legal problems. Because modern law requires that persons with disabilities or illnesses be integrated into the mainstream of society, past responses to those with communicable diseases are no longer acceptable. Laws dealing with AIDS patients will have to evolve gradually and build upon commonsense solutions to problems.

This paper fortifies and defends the so called Sufficiency Argument (SA) against Classical Invariantism. In Sect. 2, I explain the version of the SA formulated but then rejected by Brown (2008a). In Sect. 3, I show how cases described by Hawthorne (2004), Brown (2008b), and Lackey (forthcoming) threaten to undermine one or the other of the SA’s least secure premises. In Sect. 4, I buttress one ...