Final answer:
An individual who joins a group because of a specific cause they feel strongly about is motivated by purposive incentives. These incentives appeal to personal values and the desire to support the organization's goals, as seen in the ACLU's surge in membership post-9/11 due to civil liberties concerns.
Explanation:
Purposive Incentives:
When an individual joins a group because there is a specific cause they feel strongly about, this is an example of purposive incentives. Purposive incentives lead people to join and contribute to an organization with the goal of helping the organization achieve its objectives, particularly when those objectives align with the individual's personal values or causes.
For instance, after the 9/11 attacks, membership in the American Civil Liberties Union (ACLU) surged as the organization worked to address concerns about civil liberties being affected by the government's antiterrorism campaign. Similarly, members may also join groups like the Union of Concerned Scientists out of a commitment to address issues such as climate change. Essentially, purposive incentives appeal to individuals' dedication to a cause, overriding collective action problems through shared principles and goals.