At a certain level of abstraction impulses and institutional obligations are strikingly similar. To have a grasp of it, it is important to take into account the dimension of desire. Often, our desires are frustrated. Sometimes because they are conflicting, incompatible or simply impossible. Beside this, we have to face the others; we need them, we cannot be by ourselves, but they pose a continuous threat to the satisfaction of our desires. In this line of thought, Sartre's "hell is the other people" is the too often quoted, perhaps out of context, sentence. Even if, perhaps, Sartre had not this in mind, the problem remains: we may like it or not, but we have to deal with a social world. We believe that a good way to have a deeper understanding of the problem of the others is by looking at these two notions --impulses and institutions-- in the case of cooperation. Someone can have the impulse to cooperate with someone else vs the obligation to cooperate with her. In both cases this can happen independently from the desires of the cooperator. A formal account of "impulses" is achievable in the realm of modal logics. Kanger and others' logics of agency "bringing it about", can be enriched with cognitive attitudes. The logic can be given a mathematical semantics and a sound and complete axiomatization. Proving theorems in the logic can be done algorithmically with a computational complexity requiring only polynomial space.