What are P.F. Strawson's reactive attitudes?

In his influential 1962 paper, "Freedom and Resentment," the British philosopher P.F. Strawson introduced a compatibilist perspective on moral responsibility grounded in human psychology.1

Strawson argued that holding individuals morally responsible is essentially a matter of experiencing "reactive attitudes"—emotions such as resentment, anger, and gratitude—in response to the actions of others. According to this view, the metaphysical debate over whether agents act freely is secondary; what truly matters is the role these feelings play in our interpersonal relationships.1

Strawson maintained that because humans naturally and inevitably experience these reactive attitudes, we are justified in holding them regardless of the truth or falsity of determinism. However, critics note that these attitudes are not always reliable barometers for moral responsibility, as they can be significantly altered or dismissed when new factual information about an agent's circumstances is revealed.1