"The one-year-old decided to take justice into his own hands. He had just watched a puppet show with three characters. The puppet in the middle rolled a ball to the puppet on the right, who passed it right back to him. It then rolled the ball to the puppet on the left, who ran away with it. At the end of the show, the 'nice' puppet and the 'naughty' puppet were brought down from the stage and set before the boy. A treat was placed in front of each of them, and the boy was invited to take one of the treats away. As predicted, and like most toddlers in this experiment, he took it from the 'naughty' one--the one who had run away with the ball. But this wasn't enough. The boy then leaned over and smacked this puppet on the head."In his book Just Babies: The Origins of Good and Evil, Paul Bloom reports this as one of the experiments conducted at the Infant Cognition Center at Yale University (p. 7). He presents these experiments as showing that Charles Darwin was right in claiming that evolved human nature shows a natural moral sense--a sense of right and wrong--that is manifest in babies in the first few years of life, appearing at such an early age that it must be a natural instinct that requires little or no social learning. (Bloom summarized some of his reasoning in an article in the New York Times Magazine here.)
Bloom also argues that these experiments confirm Adam Smith's moral philosophy in The Theory of Moral Sentiments, because they show that Smith was right in observing that we are naturally social animals, with evolved propensities to care about our fellow human beings, a care that is expressed as sympathy or empathy, through which we judge others and judge ourselves as we appear in the eyes of others, judgments that are expressed as moral sentiments of approbation or disapprobation. When we see people suffering unfair injuries, we sympathize with their suffering and share their resentment against those who have injured them, because we have imaginatively projected ourselves into their situations--perhaps even projecting ourselves into a puppet show. That resentment against injustice is the natural ground of rights, because we judge rights from wrongs: human beings have the right not to be injured in ways that would elicit our moral resentment. This is what I have called Smith's reflective liberal sentimentalism (here, here, and here).
I use Michael Frazer's term "reflective sentimentalism" to indicate that Smith's moral psychology combines reason and emotion in explaining moral judgment. The moral emotions--such as love, indignation, guilt, and shame--provide the motivation for moral experience. Moral reasoning elicits and directs those moral emotions. The moral emotivists (like Jesse Prinz and Jonathan Haidt) who deny the role of reason in morality and the moral rationalists (like Immanuel Kant and Peter Singer) who deny the role of emotion are both wrong. The reflective sentimentalists (like Smith and David Hume) rightly see the complex interaction of reason and emotion in human moral experience. Darwinian science can explain how this moral psychology is rooted in evolved human nature.
I call this reflective sentimentalism "liberal" for three reasons. First, it recognizes the natural separateness of individuals and the moral claims that individuals make. As members of the same species, we share those general propensities or generic natural desires that constitute our human nature. But we are also unique in our identities as individuals with personal temperaments and social histories. For the harmony of society, there must be some shared experiences between individuals based on sympathy. But sympathy can never be perfect in the sense of being a complete unity of spectator and actor, because this would deny the separate identity of the two individuals. "Though they will never be unisons," Smith observed, "they may be concords, and this is all that is wanted or required" (TMS, I.i.4.8).
The second reason for calling this moral psychology liberal is that it assumes the liberal no-harm principle as the standard for justice. Smith claimed that justice was a "negative virtue," in that it hindered us from any unprovoked harming of our neighbor. Harmful actions deserve punishment coming from the resentment of the person harmed and the sympathetic resentment of the spectator. By comparison, beneficent actions deserve reward coming from the gratitude of the person benefited and the sympathetic gratitude of the spectator; but beneficence cannot be extorted by force. "Resentment seems to have been given us by nature for defense, and for defense only. It is the safeguard of justice and the security of innocence. It prompts us to beat off the mischief which is attempted to be done to us, and to retaliate that which is already done; that the offender may be made to repent of his injustice, and that others, through fear of the like punishment, may be terrified from being guilty of the like offence. It must be reserved therefore for these purposes, nor can the spectator ever go along with it when it is exerted for any other" (TMS, II.ii.1.4). Here we see the Golden Rule of the Law of Nature: "As every man doth, so shall it be done to him, and retaliation seems to be the great law which is dictated to us by Nature" (TMS, II.ii.1.10). The Golden Rule is enforced by the "animal resentment" that moves us "to return evil for evil" (II.1.1.4, II.iii.3.4). This is what John Locke called the "executive power of the law of nature"--the natural propensity to punish those who injure us.
The third reason for calling Smith's reflective sentimentalism liberal is that it explains morality through the liberal idea of unintended order. Smith sees morality as a self-enforcing order arising unintentionally through the free exchanges of individuals acting to satisfy their own individual desires. Individuals are naturally moved by the desire for a mutual sympathy of sentiments, so that they exchange personal sentiments and moral judgments with one another, which creates commonly shared standards of morality. Such an unintended order can be contrasted with an intended order that has been rationally designed by some mind or group of minds for a deliberately planned purpose. (I have developed this thought here.)
Consider how Bloom's experiments with babies illustrate these points. The toddler who recognized the naughty puppet and decided that he deserved punishment showed a combination of reason and emotion. He had the cognitive capacity to understand that the puppet in the middle had been harmed by the puppet on the left who ran away with the ball. He also had to sympathize with the imagined resentment of the puppet victim, which motivated his punishment of the bad puppet by taking away the treat and slapping him. Notice that this third-party punishment is a disinterested judgment, in the sense that it concerns actions that don't directly affect the baby himself.
The cognitive understanding of the puppet show by itself would not have motivated the moral judgment without the moral emotion of sympathetic resentment. Psychopaths illustrate this. Bloom relates the story of a thirteen-year old mugger who viciously attacked elderly women. When a reporter asked him about the pain he had caused a woman, the boy was surprised by the question and responded: "What do I care? I'm not her." He had a rational understanding of what he had done, but his moral judgment was impaired by his lack of moral emotions such as sympathy and guilt.
If these babies show a naturally evolved propensity to third-party punishment, then we need to explain the evolutionary process that produced. There are at least three theories for this. We might explain this through group selection, in that groups with third-party punishment tended to outcompete groups without such punishment. Or we might explain this through individual selection, in that individuals inclined to third-party punishment earned good reputations that enhanced their survival and reproduction. Or we might explain this though an evolutionary combination of revenge and empathy, in that individuals imagine themselves in the shoes of a victim and then respond as if they themselves had been harmed.
Although I have said that these babies show third-party punishment as a disinterested judgment, this is not totally disinterested or impartial, because the babies favor those close to them--their relatives and others in their group--over strangers. Infants prefer the voices of their mothers over strange voices, and they prefer those who speak the native language over those speaking foreign languages. They fear strangers.
Some studies have found that children often favor peers of the same race and think that they are better people. But this is true mostly for children in racially homogeneous schools. Children in racially diverse schools don't care about race. This suggests that there is a natural bias to favor one's own group over others, but social contact with other people can expand one's circle of group identity. Forming a coalition to compete with outsiders is part of our evolved human nature, but identifying those who do and do not belong to our coalition depends upon our social environment. The famous Robbers Cave experiment of Muzafer Sherif and the "minimum group" experiments of Henri Tajfel show that any arbitrary assignment of people to different groups can quickly create an Us versus Them psychology.
We can see this at work in Donald Trump's xenophobic rhetoric supporting his anti-immigrant policies, as in his warning about the "invasion" of people from Latin America. His opponents have to counter this by portraying Hispanic immigrants in a sympathetic manner as victims of unjustified harm.