The paper introduces a semantics for the language of classical first order logic supplemented with the additional operators and . This semantics understands formulas as tasks. An agent (say, a machine or a robot), working as a slave for its master (say, the user or the environment), can carry out the task if it can carry out any one of the two tasks , , depending on which of them was requested by the master; similarly, it can carry out x(x) if it can carry out (x) for any particular value for x selected by the master; an agent can carry out if it can carry out as long as it has, as a slave (resource), an agent who carries out ; finally, carrying out P, where P is an atomic formula, simply means making P true; in particular, is a task that no agent can carry out. When restricted to the language of classical logic, the meaning of formulas is isomorphic to their classical meaning, which makes our semantics a conservative extension of classical semantics. This semantics can claim to ...