Look What I Found in the Rabbit Hole...

Freewill... is an illusion. However, because human beings experience gratitude and resentment, the argument comes to a definite albeit tricky close. Aside head injuries and certain afflictions, human beings are married to gratitude and resentment. And yet, in the face of the phantom, gratitude and resentment presuppose the literal existence of freewill. Within this goofy tracery, I find the very fact that we have ability to examine our circumstances from a high enough orbit to make these sorts of examinations is a testament to the possibilities of human understanding. Here is the IEP summary of Peter Strawson's contribution to the question. 

Strawson’s Reactive Attitudes
​In an influential article, Peter Strawson argues that many of the traditional debates between compatibilists and incompatibilists (such as how to understand the ability to do otherwise) are misguided [P. Strawson (1963)]. Strawson thinks that we should instead focus on what he calls the reactive attitudes—those attitudes we have toward other people based on their attitudes toward and treatment of us. Strawson says that the hallmark of reactive attitudes is that they are “essentially natural human reactions to the good or ill will or indifference of others toward us, as displayed in their attitudes and actions.” Examples of reactive attitudes include gratitude, resentment, forgiveness and love. Strawson thinks that these attitudes are crucial to the interpersonal interactions and that they provide the basis for holding individuals morally responsible. Strawson then argues for two claims. The first of these is that an agent’s reactive attitudes would not be affected by a belief that determinism was true:
The human commitment to participation in ordinary interpersonal relationships is, I think, too thoroughgoing and deeply rooted for us to take seriously the thought that a general theoretical conviction might so change our world that, in it, there were no longer such things as inter-personal relationships as we normally understand them.… A sustained objectivity of inter-personal attitude, and the human isolation which that would entail, does not seem to be something of which human beings would be capable, even if some general truth were a theoretical ground for it.
Furthermore, Strawson also argues for a normative claim: the truth of determinism should notundermine our reactive attitudes. He thinks that there are two kinds of cases where it is appropriate to suspend our reactive attitudes. One involves agents, such as young children or the mentally disabled, who are not moral agents. Strawson thinks that we should not have reactive attitudes toward non-moral agents. The second kind of case where it is appropriate to suspend our reactive attitudes are those in which while the agent is a moral agent, her action toward us is not connected to her agency in the correct way. For instance, while I might have the reactive attitude of resentment towards someone who bumps into me and makes me spill my drink, if I were to find out that the person was pushed into me, I would not be justified in resenting that individual. The truth of determinism, however, would neither entail that no agents are moral agents nor that none of an agent’s actions are connected to her moral agency. Thus, Strawson thinks, the truth of determinism should not undermine our reactive attitudes. Since moral responsibility is based on the reactive attitudes, Strawson thinks that moral responsibility is compatible with the truth of determinism. And if free will is a requirement for moral responsibility, Strawson’s argument gives support to compatibilism.

The IEP page: http://www.iep.utm.edu/freewill/#SH5c