Is Moral Responsibility Logically Possible?
There is a well-known argument purporting to show that human beings are not morally responsible, i.e. appropriate recipients of praise and blame, which goes as follows.  What you do results from the way you are—your psychology. But the way you are is fixed by heredity and environment—nature and nurture. You act as you do because of the influences on your psychology. But you had, and have, no control over those influences: you are not responsible for your genes and upbringing. These are given to you independently of your will. But if that is so, how can you be held responsible for what you do, since it results from factors beyond your control? Your criminal tendencies are determined by what you were born with and the environmental influences brought to bear on you; they are not the upshot of your will (decision, intention). But they are what incline you to criminal acts—others may not be so inclined. It is just your bad luck that you are the way you are. You can’t be blamed for it, any more than a falling tree can be blamed for crushing you. You can’t help being the way you are. Thus you are not morally responsible for what you do.
There is much to be said about this argument, but I want to focus on a specific question: Does it show that human beings are not morally responsible or that no being could be morally responsible? Our desires are fixed by heredity and environment, and hence are not our responsibility, but is that a logical truth? Let me first note that the question generalizes to prudential responsibility: we also take ourselves to be proper objects of praise and blame according as we behave prudently or imprudently, but isn’t this determined by factors outside our control, namely our genes and upbringing. So how can we be held responsible for whether we behave prudently? Do we think animals are proper objects of prudential praise and blame? Do we say to the cat, “It was foolish of you to climb that tree—you have only your self to blame”? But why are humans different given that they too have their psychological nature fixed by causal factors beyond their control? It may be said that humans can resist the desires they are given, but how do they resist except by the psychological capacities also given to them by nature or nurture? Whether you have a strong will or a weak will is a matter of the constitution you are given by nature and nurture and is not “up to you”: it comes from having the right genes or the right upbringing. Some people are more prone to addiction than others, but this is not something they have chosen; it is just part of their given nature, and not subject to praise and blame. So we are not prudentially responsible and also not morally responsible. Responsibility presupposes the causa sui (self-causation, self-determination), but humans are not self-caused; they are caused by factors outside themselves. Even if we are partly self-created, we are not wholly so, and thus anything about us that is not self-created (most of it) is not a candidate for assessment of responsibility, moral or prudential.
This argument seems powerful in the case of human beings and other animals, but does it show that all possible beings lack responsibility? One might wonder about God: can God not be praised or blamed because he doesn’t choose his own nature (assuming that he doesn’t)? If God is just made the way he is, actions resulting from his nature are not up to him; they simply flow from his given nature (e.g. being all good). But this seems like a suspect result: is the notion of responsibility so flawed that not even God can count as responsible? If God performs a virtuous act and we want to praise him, should we refrain from doing so on the ground that God’s nature is not the result of his will? And how could God cause his own nature except by already having some sort of nature, in which case he is not responsible for that? Isn’t the argument proving too much? Consider a species of being with the following property: they decide what desire set to possess. They are like beings in the Original Position in that the desires they will have in life are not fixed by factors outside their control but by their own decisions: no heredity, no environment, just their own acts of will. Suppose some choose a virtuous set of desires, being attracted by the idea of sainthood and dazzled by the Form of the Good; while others choose less elevated desires, feeling the appeal of a life of wine, women and song, which they think will be a lot more fun than a life of bloodless virtue. They then set out on their lives and act according to the desires they have chosen: saints and sinners, respectively. Now when the question of praise and blame arises they can hardly reply by asserting that their desires were not up to them, since they were. They chose them: their desires were self-determined. These beings choose the personality type they possess. So they can’t dodge the question of responsibility by claiming non-self-determination of desires. So on the face of it moral responsibility is logically possible.
This doesn’t help humans, of course, since their desires are not self-determined (except perhaps marginally), but at least it shows that the concept of responsibility is not hopelessly confused and contradictory. We have discovered empirically that human desire has certain sorts of cause, which disqualify humans from responsibility for their actions, but the concept itself is viable and applicable to possible beings (maybe God, my imaginary species). But it may be objected that this is wrong because a decision about what desires to have must issue from other desires over which the agent has no control. I said that one group chooses virtuous desires while another group chooses more worldly desires that might well lead them into temptation: but on what basis did they so decide? Mustn’t they have had certain second-order desires to go for one set of first-order desires rather than another? Here is where things get messy and murky, philosophically speaking. Is it really logically necessary that such second-order desires must exist in order for a decision about first-order desires to be possible? Couldn’t my beings simply opt for one set of desires and not the other at random or on a whim or because of a considered judgment about what sort of life they deemed more valuable? A philosophical theory of motivation is now driving the argument not the empirical facts of human nature. So my point is to make a firm distinction between thisargument and the argument that applies to human beings: that latter argument seems solid given the facts of human nature, but the other argument begs many conceptual questions about the nature of motivation. It threatens to turn into this argument: Every psychological being must have a nature that is not determined by the decisions of that being, since all decisions rest on prior psychological facts; so no psychological being can ever be responsible for its actions. Whether that argument is sound or not—or well-formulated enough to be debated—it is not the same as the argument that moral responsibility is not possible in a being whose (first-order) desires do not result from its will. Intuitively, the possible beings I described are responsible for their actions in a way that we are not, and it takes a fancy philosophical argument to undermine that conviction—the idea that it is an a prioriconceptual truth that all decisions rest on antecedent desires (in some sense of “desire”). The important point is that the possible beings can’t excuse themselves from blame for bad actions by insisting that their desires have causes beyond their control, since they chose them. Suppose they can at any moment revise their desire set simply by choosing to do so, but they refuse to make that choice—they choose to keep on having desires that lead them to bad acts. How can they defend themselves by claiming that they can’t alter their desires? They can; they just choose not to. They keep succumbing to an addictive desire that is causing havoc in their life while they could simply wish the desire away (as we cannot): they can’t plead that the desire is beyond their control. They are the exact opposite of us so far as will and desire are concerned; so it can’t be that we are on a par when it comes to responsibility. Intuitively, they are responsible for their addictive behavior, while a human baby born with a stubborn addiction to heroin is not. In the sense in which humans are not responsible, they are responsible; so the concept has possible application. This explains why we have the concept, given that it doesn’t apply to us: we simply had mistaken ideas about the etiology of human desire (as opposed to a confused concept), and now we realize that human desire originates in facts outside of human will—we can’t in fact choose to revise our desires (or our proneness to give in to them). We have discovered the empirical psychological fact that human psychology is (largely) the result of heredity and environment, and not decision in vacuo.
What undermines responsibility is the recognition that our ability to refrain from acting on desire is not something that results from choice but from factors we don’t and can’t control (genes, upbringing), but this doesn’t apply in cases stipulated to involve freely chosen desires—here the existence and force of desire is subject to the agent’s will. So we can describe coherent cases in which agents are responsible for their actions, pending some proof that even in such cases there is an ultimate lack of responsibility. In other words, it takes an abstract and rather obscure philosophical argument to undermine responsibility even in these kinds of cases. Maybe that argument could be produced, but it would require premises that exceed what is necessary to undermine human moral responsibility. 
 This essay was prompted by a remark I heard from a woman commenting on the Bill Cosby case: she said that he clearly had a psychological problem that led to his sexual assaults but that he should have sought help to get over that problem, thus implying that he may not have been responsible for the assaults but he was responsible for not seeking help to remove the desires that led to them. The same might be said of someone with a drug addiction, especially if removing the desires in question is not that difficult.