In all those circumstances, we become used to consulting our reason as to what the best course of action is, and to settle on the one that will give us the greatest satisfaction afterwards, and thus we acquire the idea of moral evil, that is of an act that is harmful to others and which is prohibited by reason.
This definition strikes me as more accurate than the one proposed by Vauvenargues, who says that moral good and evil refer to whatever is more useful or harmful to humanity in general. These two definitions are fundamentally the same one, as any good or evil that reason approves or disapproves of corresponds to that which is useful or harmful to humanity. But Vauvenargues’ definition is less precise and harder to grasp because it does not take into account the idea that moral good and evil can be found even in the common man. For ordinary reason and conscience are not enough to understand good and evil from a universal perspective. Yet it matters more than is sometimes thought, in defining moral concepts that we should prefer those definitions that the least enlightened of men may grasp. For when it comes to uncovering the general laws ruling the human heart, the most reliable and enlightened reason is that which is the most common.--Sophie de Grouchy, Letters on Sympathy, Letter V, translated by Sandrine Berges.
While there is some evidence that Sophie de Grouchy (recall this recent post) was familiar with Bentham's early works, the main notion of 'utility' that she deploys is, in fact, a bit closer to eighteenth century thinkers like Beccaria, Hutcheson, Helvetius, and Hume than Bentham's. In that sense, 'utility' means something like 'public good' (sometimes she uses 'common utility' or 'general utility' to capture notions related to this). Not unlike Smith, she clearly evaluates social institutions like the law in such consequentialist terms. The main consequences that matter are pleasure and virtue. She thinks that such utility can come in degrees. But unlike Bentham, she does not offer a calculus nor aims to maximize the utility of individuals.
In one case she also treats utility as something that an individual can have in relationship to another individual: "we now see how we are disposed to a particular sympathy for those we are tied to by utility or pleasure," (Letter II). Here she uses utility as an explanation for a directed sympathy with somebody else. That is, if another is -- because of her, say, riches, influence, or status -- useful to us, we are likely to feel sympathy for her. Again, this is unlike the Benthamite notion, where utility is related to a hedonic or psychological property of experience. (As it happens, Grouchy helpfully distinguishes utility from pleasure in the quoted passage.)
Her main conception of utility is also relevant when it comes to her sole mention of Vauvenargues (1715-1747), who seems unknown among philosophers today. Vauvenargues, an aristocrat, was also little known in his own, short life; but he was befriended by Voltaire who drew attention to his writings. Above, Grouchy quotes Vauvenargues as holding "that moral good and evil refer to whatever is more useful or harmful to humanity in general." The idea that 'good' just is what is useful can be traced back to Hobbes and Spinoza. But the idea that this should be understood in terms of humanity in general seems original to Vauvenargues. (Let me know if you know another source!) It presupposes a very cosmopolitan understanding of the public good. Not unlike Grouchy, Stoicism greatly influenced on Vauvenargues in his youth, although there is debate about his mature views (see here). Proto-utilitarians (like Hutcheson, Helvetius, and Beccaria) tend to treat such utility in terms of the greatest number not in terms of humanity as such.
Grouchy mentions Vauvenargues in order to contrast his conception of good and evil with her own conception of moral evil, "that is of an act that is harmful to others and which is prohibited by reason." Grouchy here presupposes a distinction between moral and physical pains. The contrast between the 'moral' and 'physical' was a standard one in the second half of the eighteenth century. The 'physical' refers to bodies or matter—so 'physical evils' are bodily pains. The 'moral' refers to what we would call 'social,' but it used to refer to things connected to minds (in a broad sense). So, a 'moral evil' is a social harm.
Grouchy's criticism of Vauvenargues is, a bit complex. In part, he is treated as a misguided elitist who fails to see that the working poor are capable of sound moral evaluation. But her grounds for criticizing Vauvenargues are itself a bit elitist: that the working poor will lack understanding of such a cosmopolitan conception of humanity in general. She states the point, however, in egalitarian way, "we should prefer those definitions that the least enlightened of men may grasp." The underlying point is a serious one, she rejects a kind of elite, moral expertise: the most reliable and enlightened reason is that which is the most common, that is, found among the working poor.
The other reason for calling her criticism 'complex' is that while criticizing Vauvenargues's definition, she also claims that, in fact, their definitions actually agree. That is, there is a sense in which their definitions are meant to track a common (and cosmopolitan) good (or evil). This turns on her understanding of reason, which – to simplify – is in her hands not just a psychological faculty that (as in Hume) can calculate the foreseeable effects or outcomes of actions, but also a kind of cosmopolitan principle that (as in Smith) demands from us that each of us is treated equally, or impartially. So, a moral evil is a harm to others when that violates this cosmopolitan principle.