 Parikh (1988, 1991, 1992) proposed the use of game theory to account for disambiguation and implicature. As it turns out, the same proposal can be used to account for Horn’s division of pragmatic labour as well. Parikh assumes that a message, or form, \(f_u\), is semantically ambiguous, and can have a stereotypical interpretation, \(t_{st}\), and a non-stereotypical interpretation \(t_{\neg st}\), with \(P(t_{st}) \gt P(t_{\neg st})\). Both meanings, however, could be expressed unambiguously as well by a more complex form. Interpretation \(t_{\neg st}\), for instance, can be expressed not only by \(f_u\), but by form \(f_m\) as well that literally expresses it. As is usual in so-called costly signalling games, and also consistent with Parikh’s proposal, the sender’s utility function can be decomposed into a benefit and a cost function, \(U_s (t,f,i) = B_s (t,i) - C(f)\), where \(i\) is an interpretation. We adopt the following benefit function: \(B_s (t,i) = 1\) if \(i = t\), and \(B_s (t,i) = 0\) otherwise. The cost of the ambiguous message \(f_u\) is lower than the cost of the unambiguous message \(f_m\). We can assume without loss of generality that \(C(f_u) = 0 \lt C(f_m)\). In the use of signalling games for the analysis of human communication it is standard to assume that it is always better to have successful communication with a costly message than unsuccessful communication with a cheap message, which means that \(C(f_m)\), though greater than \(C(f_u)\), must remain reasonably small. If we limit ourselves to a game with 2 states, \(t_{st}\) and \(t_{\neg st}\), and three messages, \(f_u\) and the two forms that literally express the two states, and think of sender and receiver strategies as before, the combination of sender and receiver strategies that gives rise to the bijective mapping \(\{\langle t_{st},f_u\rangle , \langle t_{\neg st},f_m\rangle \}\) is a Nash equilibrium of this game. Intuitively, this is also the correct solution of the disambiguation game, because the ambiguous message \(f_u\) expresses the stereotypical interpretation \(t_{st}\), while the non-stereotypical state \(t_{\neg st}\) is expressed by the marked and costlier message \(f_m\). Unfortunately, also the mapping \(\{\langle t_{st},f_m\rangle , \langle t_{\neg st},f_u\rangle \}\)—where the lighter message denotes the non-stereotypical situation—is a Nash equilibrium of the game, which means that on the present implementation the standard solution concept of game theory cannot yet single out the desired outcome.