I contrast an ecological account of natural agency with the traditional Cartesian conception using recent research in bacterial cognition and cellular decision making as a test case. I argue that the Cartesian conception—namely, the view that agency presupposes cognition—generates a dilemma between mechanism, the view that bacteria are mere automata, and intellectualism, the view that they exhibit full-blown cognition. Unicellular organisms, however, occupy a middle ground between these two extremes. On the one hand, their capacities and activities are too adaptive to count as mere machines. On the other hand, they lack the open-ended responsiveness of cognitive agents to rational norms. An ecological conception of agency as the gross behavioral capacity to respond to affordances, I argue, does not presuppose cognition and allows for degrees of agency along a continuum, from the simplest adaptive agents, such as unicellular organisms, to the most sophisticated cognitive agents. Bacteria, I conclude, are adaptive agents, hence not mere automata, but not cognitive agents.