Scanlon has tried to narrow the problem of the nature of morality to judgments of right and wrong, and to our reasons for accepting or rejecting such judgments.

He finds that moral judgments depend upon principles that we can justify to others in the sense that such principles could not be reasonably rejected.

When I ask myself what reason the fact that an action would be wrong provides me with not to do it, my answer is that such an action would be one that I could not justify to others on grounds I could expect them to accept. This leads me to describe the subject matter of judgments of right and wrong by saying that they are judgments about what would be permitted by principles that could not reasonably be rejected, by people who were moved to find principles for the general regulation of behavior that others, similarly motivated, could not reasonably reject. In particular, an act is wrong if and only if any principle that permitted it would be one that could reasonably be rejected by people with the motivation just described (or, equivalently, if and only if it would be disallowed by any principle that such people could not reasonably reject).

(What We Owe To Each Other, p.4)

This idea of a shared willingness to modify our private demands in order to find a justification that others have a reason to accept also resembles various "social contract" ideas like those of Thomas Hobbes and Jean Jacques Rousseau. Indeed, Scanlon calls his moral theory "social contractualism."

Scanlon says that his theory is a departure from standard Kantian deontology, which assumes that our "self-legislation" according to a moral law (the categorical imperative) is "autonomous." He recognizes that the cultural dependence of his theory makes it openly "heteronomous" and dependent on hypothetical imperatives.

He says:

[My] account of the reasons supporting our concern with the rightness of our actions is very different from Kant's. My strategy is to describe these reasons in substantive terms that make clear why we should find them compelling. While Kant sought to explain the special authority of moral requirements by showing how they are grounded in conditions of our rational agency, I try to explain the distinctive importance and authority of the requirements of justifiability to others by showing how other aspects of our lives and our relations with others involve this idea. The result is an account of right and wrong that is, in Kant's terms, avowedly heteronomous.

(What We Owe To Each Other, p.6)

Scanlon thus narrows the focus of his moral research to the domain of our duties to other people, requirements to aid them, prohibitions on harming them, etc. This is the subject matter of most contemporary moral philosophy, he says. Rather than giving it a new technical name, he calls it simply "What We Owe To Each Other."

Because the community process of arriving at principles that cannot be reasonably rejected resembles the deliberative process whereby an individual agent evaluates presented alternatives and arrives at a decision, Scanlon calls his idea a "system of co-deliberation."

The part of morality with which I am mainly concerned is sometimes seen as a system of restraints which we accept in order to gain protection against the harmful conduct of others. Moral criticism (in this context, chiefly blame) is then seen as a sanction that is supposed to move people to comply with these constraints. On my view, by contrast, this part of morality is not, fundamentally, a mechanism of control and protection but, rather, what I call a system of co-deliberation, and moral reasoning is an attempt to work out principles that each of us could be asked to employ as a basis for deliberation and accept as a basis of criticism. Seeking such principles is part of what is involved in recognizing each other's value as rational creatures, Our needs for protection and for the assistance of others play a role in determining which principles it is reasonable for us to reject and which to accept, and hence in determining which actions are right and wrong.

(What We Owe To Each Other, p.268)

His analysis of permissibility starts with the doctrine of "double effect," the idea that a given action may be permissible or impermissible depending on the intentions of the agent. In the famous "trolley problem" of Philippa Foot, a runaway trolley threatens to kill five workers ahead on the track, unless it is diverted to a siding that would unfortunately kill a single worker.

Double effect says that although the death of the single worker is foreseen, it is nevertheless permissible as long as the intent is to save the lives of the five. Should the intent be to kill the one in order to save the five, the diversion would be impermissible.

Scanlon argues that the intention of the agent depends on attitudes that may impair his or her relations with others. In short, he or she may not have proper regard for "what we owe to each other." For Scanlon, what he calls the "meaning" of an action depends critically on the agent's attitudes or intentions. Having the wrong attitudes or intentions renders the agent blameworthy.

Being blameworthy may justify others who may blame the agent, but the content of the blame depends on the significance, for the person doing the blaming, of the agent and what he has done. This significance depends on the attitudes of the agent and those of the person doing the blaming, which affects "what they owe to each other.".

In his introduction to Moral Dimensions, Scanlon says:

To say that in a certain action the agent was "just using" another person can be an observation about the meaning of that action, and the fact that an action has this meaning can sometimes be relevant to its permissibility.

To say that an action is blameworthy is to make a claim about its meaning: to claim that the action indicates something about the agent's attitudes that impairs his or her relations with others. To blame someone, in my view, is to understand one's relations with that person as modified in the way that such a judgment holds to be appropriate. In Chapter 4 I elaborate and defend this interpretation of blame, explaining how it differs from and should be preferred to other interpretations that take blame to be a kind of negative assessment, a sanction, or the expression of some moral emotion, such as resentment. I examine the implications of this interpretation for the ethics of blame — for who may be blamed, who has standing to blame, and when one must blame. I also examine why blame might be thought to be appropriate only for actions that are undertaken freely, and explain why moral blame, as I understand it, does not presuppose free will.

In the course of this book I argue for a number of particular moral claims, including claims about which actions are permissible, about when intent matters to permissibility, and about various forms of moral responsibility. I hope that readers will be persuaded by what I have to say about these questions. But another important aim of the book is to identify and call attention to differences between the general moral notions in terms of which these particular judgments are expressed. These general notions are the dimensions of moral thinking referred to in the title: permissibility, meaning, and blame. My main claims are about how permissibility is to be understood; how it differs from meaning; how blameworthiness is a species of meaning; and how blame can be understood as a class of responses to this kind of meaning. I hope that readers who disagree with my particular moral claims will be led to reflect on the way that they understand these general moral notions. Iii particular, I hope they will consider whether the question of right and wrong as they understand it is what I am calling the question of permissibility. Similarly, I hope that those who disagree with me about blame will be inspired to make clear what they take moral blame to involve, and why blame as they understand it should be thought to require a particular kind of freedom.

(Moral Dimensions, p.6)

Many people believe that blame presupposes freedom, and thus that it is never appropriate to blame people if all of their actions are caused by factors outside of them, over which they have no control. What is not commonly explained is why this should be so — or rather, what it is about blame that entails this requirement of freedom. In this section I will consider two possible explanations, which I call the requirement of psychological accuracy and the requirement of adequate opportunity to avoid. My aim is to examine these reasons for thinking that blame requires some kind of freedom and to see how they apply when blame is understood in the way I am suggesting.

The requirement of psychological accuracy is straight forward. Insofar as blame depends on the reasons for which an agent acted, a judgment that blame is called for can be modified or undermined by factors that change our view of what those reasons were. Mistaken belief and coercion are factors of this kind. The fact that a person acted in a way that caused harm to someone else may seem to indicate a blameworthy lack of concern for the other's interests. But the requirement of psychological accuracy bars us from drawing this conclusion if the agent reasonably believed (albeit mistakenly) that this action would not be harmful, or that it was necessary in order to prevent a much greater harm to the person.

Similarly, an agent who knowingly causes harm to another is blameworthy if he or she does this gratuitously, or out of indifference to that person's interest. But the agent may not be blameworthy, or may be subject only to a different and lesser form of blame, if she caused the harm only because someone threatened her with grave harm if she did not. So, for example, a bank teller faced with a credible threat of deadly force should not be blamed for giving cash to a bank robber.

It is sometimes said that coercion renders blame inappropriate in such cases because an agent acting under duress is not responsible for what she does. This seems to me a mistake. Coercion does not undermine responsibility; rather, what it does is to change what the agent is responsible for. A person who is coerced, such as the bank teller I mentioned, still acts, and acts for certain reasons. Such a person is thus responsible for what she does: that is to say, her action is fully attributable to her. The bank teller may even deserve commendation for handling a dangerous situation in a calm and careful manner.

Rather than undermining responsibility, what coercion may do is to modify the permissibility of an action or the kind of blame, if any, that it makes appropriate. In the case of the bank teller, for example, the threat of harm may justify her handing over the money, which would otherwise be wrong. And even when coercion does not render what a person does permissible, it may alter the kind of blame that is appropriate. It is one thing to inflict harm on another person gratuitously, another thing to do so (even unjustifiably) out of fear of harm to oneself. The first kind of change (in permissibility) occurs because coercion changes the reasons there are for doing what the agent did. Changes of the second kind (in blameworthiness) occur because coercion changes in the reasons on which the agent acted.

The requirement of psychological accuracy can thus explain how lack of freedom can render blame inappropriate, or modify the kind of blame that is called for. But this explanation applies only when, as in cases of coercion, the lack of freedom alters the relation between an action and the attitudes of the agent who performs it. As many have pointed out, the lack of freedom that would be entailed by a general causal determinism need not have this effect. Even if our attitudes and actions are fully explained by genetic and environmental factors, it is still true that we have these attitudes and that our actions express them.

Compatibilists have sometimes concluded from this that it is simply a mistake to think that moral assessment requires freedom from determination by outside causes. Hume, for example, argued that the tendency to think that moral assessment is incompatible with causal necessity results from a failure to distinguish between what he calls the liberty of spontaneity and the liberty of indifference. Hume believed that we lack the liberty of indifference: that our actions are governed by regular causal laws. Indeed, he said, moral appraisal depends on this, since it depends on there being regular connections between actions and the attitudes they express. But this does not mean that we lack the liberty of spontaneity — that we always act unwillingly. Laws of nature are not coercive.

Put in my terms, Hume seems to think that what he called "necessity" (causal determination of our actions) could undermine moral appraisal only by depriving us of the liberty of spontaneity, thereby conflicting with the requirement of psychological accuracy. He therefore thinks that since the existence of causal laws governing our actions does not have this effect, there is no conflict between moral responsibility and causal determination. This argument depends on the assumption that psychological accuracy is the only basis on which moral responsibility might require freedom. This may be so given Hume's account of blame, according to which it is just a sentiment of disapproval toward an agent's character. But if blame is understood in some other way, then psychological accuracy may not be the only reason for believing that blame requires freedom.

Galen Strawson, for example, believes that in order for it to be appropriate to blame a person for committing a vicious crime, it is not enough that that action should actually express reprehensible attitudes such as indifference toward the lives of others and a desire to make them suffer. The agent must also have consciously and explicitly chosen to be the kind of person who would have such attitudes and act from them. Strawson believes this because of the particular kind of moral assessment that he has in mind: the kind of moral responsibility "such that, if we have it, then it makes sense, at least, to suppose that it could be just to punish some of us with (eternal) torment in hell and reward others with (eternal) bliss in heaven."

It does seem to make no sense, or at least to be highly objectionable, for God to make people suffer an eternity of torment for their sins if God set things up in such a way that it was inevitable that they would have exactly those sins. The requirement of psychological accuracy would not be violated in such a case. The people who would be punished would really have the moral faults in question. So there must be some other reason why this punishment is so objectionable. What makes it objectionable, I suggest, is the fact that they could not in any way have avoided this terrible punishment.

It is important to understand the structure of the moral idea at work here, which I call the requirement of adequate opportunity to avoid. This requirement applies in cases in which someone has suffered a harm that people have, in general, a claim not to be subjected to. (I will call this claim "the underlying obligation.") If the person who has suffered such a harm protests that this obligation has been violated, it can be at least a partial response to this objection to say that he or she had ample opportunity to avoid the harm by choosing appropriately. More may be required to respond adequately to this protest, but at least in many cases this appeal to the opportunity to avoid is an important part of any adequate response.

In the case of hell, more surely is required. Setting things up so that some people will suffer an eternity of torment (when things need not be set up this way) requires substantial justification. It is not enough just to say that those who suffer could have avoided it by making reasonable choices. But giving people adequate opportunity to avoid this fate is at least a necessary condition. We need at least to be able to say to people who suffer this fate that they could have avoided it by choosing reasonably. So if the idea that the blameworthy are to be consigned to hell is to be defensible, people have to have adequate opportunity to avoid being blameworthy (at least in the way that entails hell as a punishment).

The requirement of adequate opportunity to avoid is not an idea of desert. The idea is not that it is fitting or appropriate that people who fail to choose wisely should suffer certain harms. It may be better that they not suffer them. The point is merely that if they do suffer these harms, then their complaint against those who allowed it to happen may be undermined if they had adequate opportunity to avoid this outcome by choosing appropriately, and that in at least some cases it is morally objectionable to allow these harms to occur unless those who suffer them had such an opportunity.

My subject here is not heaven and hell but the much milder idea of blame. But even blame is something people have good reason to dislike. It may therefore be seen as something they have some claim not to suffer, and therefore as something to which the requirement of fair opportunity to avoid may seem to apply. This is particularly so if blame is seen as a sanction — a form of unpleasant treatment that requires justification and is justified by its effects on people's behavior.

This reasoning does not apply when blame is understood in the way I am proposing. To see why, consider first why it does not apply if blame is understood merely as a kind of negative evaluation or, as Hume suggests, a sentiment of disapproval. Even understood in this way, blame is something that people have reason to dislike. We don't want people to draw, or even to have good reason to draw, negative conclusions about our relations with them. And we have reason to want them not to draw such conclusions even if they are never expressed and never affect their behavior toward us in any way. But we have no claim against others that they not draw such conclusions, so long as they have good grounds for thinking them to be correct. Since we have no such claim, there is no need to appeal to the idea of our having had "adequate opportunity to avoid" being blamed. Psychological (and moral) accuracy provide all the justification that blame requires, when it is understood in this way.

(Moral Dimensions, pp.179-85)