 Philosophers have generally held that some contingent truths are (or could be) laws of nature. Furthermore, they have thought that, if it is a law that all Fs are Gs, then there need not be any (metaphysically) necessary connection between F-ness and G-ness, that it is (metaphysically) possible that something be F without being G. For example, any possible world that, as a matter of law, obeys the general principles of Newtonian physics is a world in which Newton’s first law is true, and a world containing accelerating inertial bodies is a world in which Newton’s first law is false. The latter world is also a world where inertia is instantiated but does not necessitate zero acceleration. Some necessitarians, however, hold that all laws are necessary truths. (See Shoemaker 1980 and 1998, Swoyer 1982, Fales 1990, Bird 2005. See Vetter 2012 for criticism of Bird 2005 from within the dispositional essentialist camp.) Others have held something that is only slightly different. Maintaining that some laws are singular statements about universals, they allow that some laws are contingently true. So, on this view, an F-ness/G-ness law could be false if F-ness does not exist. Still, this difference is minor. These authors think that, for there to be an F-ness/G-ness law, it must be necessarily true that all Fs are Gs. (See Tweedale 1984, Bigelow, Ellis, and Lierse 1992, Ellis and Lierse 1994, and Ellis 2001, 203–228; 2009, 51–72.)