Informational contexts of games can include various forms of attitudes, from the classical knowledge and belief to robust (Stalnaker 1994) and strong (Battigalli &amp; Siniscalchi 2002) belief, each echoing in different notions of game-theoretical rationality. It is beyond the scope of this article to survey the details of this vast literature (cf. the next section for some discussion of this literature). Rather, we will introduce a general distinction between hard and soft attitudes, distinction mainly developed in dynamic epistemic logic (van Benthem 2011), which proves useful in understanding the various philosophical issues raised by epistemic game theory.