How did A.J. Ayer define the ability to act otherwise?

In his 1946 essay "Freedom and Necessity," the philosopher A.J. Ayer defined the ability to act otherwise through a conditional analysis. He maintained that to say one could have acted otherwise is simply to say that one would have acted differently if one had so chosen.1

This perspective is a form of compatibilism, which seeks to reconcile the existence of free will with a deterministic view of the world. By framing the ability to do otherwise as a conditional statement, Ayer suggests that an action can be considered free even if it is ultimately determined by the past, provided that the agent's choice was the deciding factor in the outcome. This interpretation is often criticized as a weak notion of freedom, as it does not necessarily satisfy the intuitive human desire for agency or provide a robust foundation for moral responsibility.1