 Some subsequent attempts to explicate knowledge had broadly “reliabilist” features, although they did not use this terminology. According to “relevant alternatives theories”, a subject is said to know p provided that they can “rule out” relevant alternatives where p does not obtain (Dretske 1970; Goldman 1976; Stine 1976; Lewis 1996). According to “truth-tracking theories”, a subject knows p provided their beliefs “track the truth” of p across modal space. Truth-tracking theorists typically cash this out in terms of subjunctive conditionals, such as “Sensitivity”: If p had been false, S wouldn’t have believed p (Nozick 1981), or “Safety”: If S were to believe p, p would be true (Sosa 1999; Williamson 2000; Pritchard 2005). These views are united by the idea that knowledge requires some form of reliability. (See the entry on the  analysis of knowledge.)