Sometimes, we act in concert with others, as when we go for a walk together, or when two mathematicians try to prove a difficult theorem with each other. An interesting question is what distinguishes the actions of individuals that together constitute some joint activity from those that amount to a mere aggregation of individual behaviours. It is common for philosophers to appeal to collective intentionality to explain such instances of shared agency. This framework generalizes the approach traditionally used to explain individual action: a behaviour is an action just in case it causally follows from the relevant intention. Contemporary philosophers of action, as well as cognitive psychologists, however, have criticised this way of explaining individual actions, favouring instead an approach that puts "control" or "guidance" as the discerning factor: a behaviour is an action just in case the agent controls it, or just in case it is guided by the agent. In this paper, I argue that we should include talk of guidance even in cases of joint action. I first show that problems of deviant causation arise also in cases of joint action, and that therefore guidance is required to face this issue. Then, I show what a "capacity to jointly guide" amounts to for an individual in a group and how joint guidance relates to individual guidance. Joint guidance is actually constituted by task co-representation and the sense of being jointly committed. I argue that an approach that favours joint guidance over collective intentions eschews a lot of metaphysical problems about collective mentality and group subjects, and it is thus more explanatorily fruitful.
