 For example, Elgin (2009; cf. Elgin 1996, 2004; Janvid 2014) and Riggs (2009) argue that it is possible for an agent to have understanding and yet lack true beliefs in the relevant propositions. For example, Elgin (2009) argues that it is essential to treat scientific understanding as non-factive. She cites a number of cases in which science has progressed from one theory to a better theory where, we would say, understanding has increased in the process even though the theories are, strictly speaking at least, false. A different kind of case that Elgin offers concerns scientific idealizations, such as the ideal gas law. Scientists know full well that no actual gas behaves in this way, yet the introduction of this useful fiction clearly improved our understanding of the behavior of actual gasses. For a defense of Kvanvig’s view in the light of these charges, see Kvanvig (2009a, 2009b; Carter &amp; Gordon 2014).