 In a bit more detail, the theory runs as follows. According to Papineau, a desire’s satisfaction condition is “that effect which it is the desire’s biological purpose to produce” (1993, 58–59), by which he means that “[s]ome past selection mechanism has favored that desire – or, more precisely, the ability to form that type of desire – in virtue of that desire producing that effect” (1993, 59). So our desires have the function of bringing about certain conditions – either conditions that enhanced the fitness of our ancestors in the distant past (if the selection mechanism in question was natural selection) or conditions that constituted a reward for us in the recent past (if the selection mechanism was a mechanism of individual learning). These conditions are the satisfaction conditions of our desires or, in other words, their contents.