'Tis not contrary to reason to prefer the destruction of the whole world to the scratching of my finger.Bloom uses the quote to make the point that babies have to have emotional reactions to good and bad, fair and unfair, before they can develop into moral adults. Reason won't suffice to put them on that path. "To have a genuinely moral system, in other words, some things first have to matter, and what we see in babies is the development of mattering."
OK, so other people's problems don't start to matter to us unless we have the right rudimentary responses, which appear to be innate. If that's so, must it really be true that reason plays no role in allocating concern so the whole world's destruction matters more than a finger scratch? Bloom actually gives a non-Humean nod to reason later in the article.
The notion at the core of any mature morality is that of impartiality. If you are asked to justify your actions, and you say, “Because I wanted to,” this is just an expression of selfish desire. But explanations like “It was my turn” or “It’s my fair share” are potentially moral, because they imply that anyone else in the same situation could have done the same. This is the sort of argument that could be convincing to a neutral observer and is at the foundation of standards of justice and law. The philosopher Peter Singer has pointed out that this notion of impartiality can be found in religious and philosophical systems of morality, from the golden rule in Christianity to the teachings of Confucius to the political philosopher John Rawls’s landmark theory of justice. This is an insight that emerges within communities of intelligent, deliberating and negotiating beings, and it can override our parochial impulses."Intelligent, deliberating and negotiating beings"are rational, right? And they do not prefer the destruction of the whole world to the scratching a finger! So Hume was a little bit right, but not entirely. He was right that moral thinking doesn't get started without moral reactions, but wrong that it's compatible with reason to care more about the scratch.
Unfortunately, Bloom muddies the waters in the next paragraph--
The aspect of morality that we truly marvel at — its generality and universality — is the product of culture, not of biology. There is no need to posit divine intervention. A fully developed morality is the product of cultural development, of the accumulation of rational insight and hard-earned innovations. The morality we start off with is primitive, not merely in the obvious sense that it’s incomplete, but in the deeper sense that when individuals and societies aspire toward an enlightened morality — one in which all beings capable of reason and suffering are on an equal footing, where all people are equal — they are fighting with what children have from the get-go.A product of culture? Transmitted by culture, yes. That's got to be at least partly so. But culture doesn't make the "general" and "universal" aspect of morality, if we come to it through "rational insight."