Typically people associate free will as a condition necessary for moral responsibility. As John Martin Fischer says:
Some philosophers do not distinguish between freedom and moral responsibility. Put a bit more carefully, they tend to begin with the notion of moral responsibility, and “work back” to a notion of freedom; this notion of freedom is not given independent content (separate from the analysis of moral responsibility). For such philosophers, “freedom” refers to whatever conditions are involved in choosing or acting in such a way as to be morally responsible.
But some philosophers separate the two. Semicompatibilists, like Fischer, think moral responsibility is compatible with determinism, and are agnostic on the issue of free will. Reverse semicompatibilists like Bruce Waller think we have free will but not moral responsibility. Dan Dennett is happy to give up the term free will altogether and concentrate on his consequentialist view of moral responsibility.
Considerations about determinism have played a major role in the debate about moral responsibility. Incompatibilists maintain that no one is morally responsible if causal determinism is true, while compatibilists maintain that one can be morally responsible if causal determinism is true. Historical examples of incompatibilists include Epicurus, Saint Augustine, and Immanuel Kant; examples of compatibilists include the Stoics, Thomas Hobbes, David Hume and John Stuart Mill.
If we want to say free will is the condition necessary for moral responsibility, we first need to be clear on what moral responsibility is. Here are three views on moral responsibility.
On a merit-based view or moral responsibility, praise and blame are appropriate in virtue of the agent meriting or deserving this reaction regardless of consequences. Whether an agent deserves praise or blame will depend on various further conditions, like having the right type of control over a choice. Merit-based views have typically been associated with incompatibilist theories of free will.
On a consequentialist view of moral responsibility, praise and blame are appropriate if this reaction leads to good consequences. This view has typically been associated with compatibilist theories of free will, though I don’t know if it is the majority view or not.
Here’s an example that can clarify the difference between the merit-based and consequentialist views: Suppose we have a criminal that by some bizarre, unforeseen chain of events was teleported to a twin Earth planet before he could serve his time in jail. This twin Earth planet has no sentient life so the criminal couldn’t ever harm anyone, and this criminal actually enjoys being on this planet. Suppose, by fortune, we also had a button that could trigger some punishment on this criminal. A proponent of the merit-based view would favor pushing the button because he deserves it, while it wouldn’t make sense on the consequentialist view.
On P.F. Strawson’s reactive-attitudes view of moral responsibility, classical compatibilists and incompatibilists both get it wrong in thinking that moral responsibility depends on abstract theoretical issues about determinism. Instead, to be morally responsible is from to be fit for reactive attitudes (e.g., resentment, admiration, gratitude, indignation, guilt, blame, approbation, and forgiveness) in our ordinary practice of life. When we consider holding someone responsible for harming us, we consider their intentions: if they didn’t intend to harm us, we do not blame them. In the ordinary practice of life, like in the harm example, thoughts of determinism don’t even arise.
The SEP categorizes the Strawson’s reactive-attitudes view as merit-based.
Strawson’s is a merit-based form of compatibilism. That is, unlike most former consequentialist forms of compatibilism, it helps to explain why we feel that some agents deserve our censure or merit our praise. They do so because they have violated, met, or exceeded our demand for a reasonable degree of good will.
But Strawson does seem to have a, per impossible, fallback condition, where we should be consequentialist.
if we could imagine what we cannot have, viz, a choice in this matter, then we could choose rationally only in the light of an assessment of the gains and losses to human life, its enrichment or impoverishment; and the truth or falsity of a general thesis of determinism would not bear on the rationality of this choice.
My own view of moral responsibility is consequentialist. I see prison more as a place of quarantine than a place where people get what they deserve regardless of consequentialist considerations. When we quarantine people with deadly viruses, we’re not giving them what they deserve; instead, we quarantine them to minimize harm. Similarly, we need to quarantine criminals by imprisoning them to minimize harm.
I think Dennett gets it right when he says we can skip talk about free will and go straight to moral responsibility. I think the issue of moral responsibility takes precedence over the issue of free will. Though the two may inevitably be entangled, I think more progress can be made if conversations start with moral responsibility rather than free will.
Strawson, P.F.. Freedom and Resentment