This paper aims at illustrating the virtues and vices of biased rationality. Starting with the virtues of biased rationality, we will illustrate the idea of Homo Heuristicus along with its fallacious dimension. We will claim that biases provide us with premissory starting points even in absence of relevant information to solve the problem at hand. In the second part, we will turn to the vices of biased rationality: we will contend that the adaptive value of fallacies are limited to those situations in which we do not have (relevant) information, whereas being in such a situation is not adaptive at all. We will point out that de-bising rationality is made possible when human learning becomes an option ecologically supported by the accumulation of knowledge in the human cognitive niche. In order to provide ground to this idea, we will employ the lens model introduced by Egon Brunswik.