The modern evolutionary account of morality supports this Lockean law of reputation understood as "indirect reciprocity," in which people are motivated to do good deeds for others as long as these good deeds win them a good reputation. Some evolutionary anthropologists have shown that the sort of hunter-gatherer bands in which human beings have lived for most of their evolutionary history most likely developed a moral order based primarily on such reputational selection favoring conformity to the customary moral rules of society.
Good and evil are nothing but pleasure and pain, Locke believes. Moral good and evil can then be understood as "the conformity or disagreement of our voluntary actions to some law, whereby good or evil is drawn upon us, from the will and power of the lawmaker" (II.28.5).
There are three kinds of laws corresponding to three kinds of lawmakers with different kinds of rewards and punishments for enforcing their laws. Divine law is God's law enforced with His eternal rewards and punishments. Civil law is the law made by human legislators exercising the force of government to enforce their laws. The law of opinion or reputation is the law established through social praise and blame in which people in every social group by a "tacit consent" determine what is virtue and vice, rewarding the praiseworthy with a good reputation and punishing the blameworthy with a bad reputation.
Locke also calls the law of reputation the philosophical law, not because philosophers make it, but because this is the law most studied by pagan philosophers when they inquire into the character of virtue and vice, because they generally assume that virtue is what is thought praiseworthy.
Locke believes that studying the "history of mankind," which includes the anthropological history of societies around the world and the American Indians, will show that most human beings have been governed mostly, if not entirely, by the law of reputation, because while people might think they can evade the laws of God or the government, they can rarely escape the punishment of censure when they offend those with whom they associate.
When Locke was accused of moral relativism, because he seemed to say that virtue and vice had no fixed meaning in being determined by the arbitrary movements of social praise and blame, he responded in two ways. First, he said that he was reporting as a matter of fact how most human beings determine virtue and vice as what is generally praised or blamed by those around them, and surely one could hardly deny this as a factual truth.
His second response was to point out that he had indicated that despite the variability and fallibility of social praise and blame as a standard of moral goodness, what people generally regard as praiseworthy or blameworthy are "as to the main" the same everywhere, and "in a great measure," they correspond to "the unchangeable rule of right and wrong," and they do not stray very far from "the Law of Nature," which is "that standing and unalterable rule by which they ought to judge of the moral rectitude and gravity of their actions" (p. 19, II.28.11).
This might seem to contradict what Locke says in denying that there are any innate practical principles, and in citing as evidence for this that some societies have practiced moral outrages like infanticide, patricide, and cannibalism. Locke observes:
"He that will carefully peruse the history of mankind, and look abroad into the several tribes of men, and with indifferency survey their actions, will be able to satisfy himself, that there is scarce that principle of morality to be named, or rule of virtue to be thought on, (those only excepted that are absolutely necessary to hold society together, which commonly too are neglected betwixt distinct societies,) which is not, somewhere or other, slighted and condemned by the general fashion of whole societies of men, governed by practical opinions and rules of living quite opposite to others" (I.2.10).Notice, however, the parenthetical remark--there are some rules that are absolutely necessary for the social order of any group, and so these rules are likely to be universally recognized, although even these rules might not be observed in conflicts with outside groups. In fact, Locke notes, there is a connection between virtue and "public happiness," in that some virtues are necessary for preserving society, and consequently most people will see that it's in their self-interest to promote those social virtues (I.2.6).
"Justice and truth are the common ties of society; and therefore even outlaws and robbers, who break with all the world besides, must keep faith and rules of equity amongst themselves; or else they cannot hold together" (I.2.2). Indeed, as Peter Leeson (The Invisible Hook, 2009) has shown in his history of pirate societies, pirate crews had to consent to the captain's code of good behavior before sailing. They were obliged to swear upon a hatchet (rather than a Bible) that they would obey the captain's articles of agreement, which had arisen as a spontaneous self-organized order to prevent these societies of outlaws from collapsing into disorder. So there really is honor among thieves.
Locke's law of reputation was reaffirmed by David Hume and Adam Smith, who stressed the extent to which morality was rooted in the natural human concern for how one appears to others and the desire, as Smith put it, for a mutual sympathy of sentiments. Charles Darwin thought this human moral sensitivity to social approbation and disapprobation could have evolved by natural and cultural selection.
In 1987, in The Biology of Moral Systems, Richard Alexander brought this line of reasoning under the term "indirect reciprocity." Kin selection theory could explain the evolution of morality among genetic kin. But it was hard to see how this could be extended to non-kin. Robert Trivers argued that the theory of reciprocal altruism could explain the moral cooperation of genetically unrelated individuals engaged in reciprocal relationships based on the idea that "I'll scratch your back if you scratch mine." Beyond such direct reciprocity, Alexander saw the possibility of indirect reciprocity--"I'll scratch your back if you have the reputation for scratching the backs of others."
This evolved morality as based on kin selection and reciprocity (both direct and indirect) does not require a morality of self-sacrifice, Alexander argues. This morality requires a conscience that can be described as "the still, small voice that tells us how far we can go without incurring intolerable risks or costs to our own interests" (107).
There are various ways in which a natural concern for one's reputation could evolve as serving one's reproductive interests. Those with good reputations might be identified as the best sexual mates, and they might elicit cooperation and generosity from others in one's society. Those with bad reputations could expect social punishments that could lessen their reproductive fitness.
Studies of foraging societies have provided some evidence that this is true. Foraging bands tend to have around 25-30 members. Of these, only about 10% to 20% are genetically related. About half are affinal relatives (in-laws). The rest are not related at all. So kin selection cannot fully explain their social cooperation (Hill et al. 2011). Direct reciprocity might explain some cooperation where two partners are directly benefiting one another. But much of the cooperation seems to depend on indirect reciprocity, where people cooperate or not based on good or bad reputation.
Christopher Boehm (2012) has gathered clear evidence for this evolution of morality through the effects of reputation. He has studied the ethnographic records for 339 hunter-gatherer societies. He has eliminated those groups with characteristics that would not have been typical for foragers in the Late Pleistocene. For example, he eliminated those groups that were dependent on missions, those that traded food with horticulturalists, those involved in the European fur trade, and those who were sedentary and began to store food. This left him with 150 groups that he could identify as "Late Pleistocene appropriate" (LPA). He then developed a system for coding the data with 232 social coding categories--such as "sharing with kin" and "aid to nonrelatives favored." So far, he has fully coded 50 out of the 150.
From that data, he can see that the most common forms of social deviance that are punished in all or almost all foraging societies are murder, sorcery or witchcraft, stealing, beating of someone, failing to share, bullying, and lying. The most common forms of punishment are gossip, ridicule, direct criticism, social distancing, group ostracism, nonlethal physical punishment, and temporary expulsion from the group. The most severe forms of punishment (particularly for murder) are the entire group killing the culprit, a group member selected to kill the culprit, and permanent expulsion from the group. When a murderer kills one person, it's assumed that someone in the victim's family will take vengeance against the murderer. When a murderer kills two or more people, he is punished by the whole group. Often the group will ask one of the murderer's relatives to kill him. And in most cases, it is a "him," because most of the deviant violence is perpetrated by men.
These groups have no formal legal systems or governments, and so these social rules are all customary norms. The enforcement of these norms through punishment is through what Locke calls "the executive power of the state of nature," or the natural right of all individuals to punish those who attack them, steal from them, cheat them, bully them, or otherwise disrupt the customary social order.
Reputation is crucial in all of this, because those reputed to be social deviants are punished, and those reputed to be cooperative and generous are rewarded. As Locke indicated, the group recognizes as virtuous those traits that conform to the customary norms of the group and as vicious those traits that violate those norms.
Boehm argues that since punishment for violating these norms lessens the reproductive fitness of the violator, then we can imagine that evolution would favor the emergence of a moral capacity for conscience, so that people would develop the ability to suppress their antisocial tendencies and to feel guilt and shame when they express those tendencies. We can confirm this by considering the evidence from neuroscience that the human brain is wired for moral judgment and moral emotions, and those few who lack this wiring (psychopaths) do not have the moral sense typical of normal people.
Alexander, Richard. 1987. The Biology of Moral Systems. New York: Aldine de Gruyter.
Boehm, Christopher. 2012. Moral Origins: The Evolution of Virtue, Altruism, and Shame. New York: Basic Books.
Hill, Kim R., et al. 2011. "Co-Residence Patterns in Hunter-Gatherer Societies Show Unique Human Social Structure." Science 331: 1286-1289.
Leeson, Peter. 2009. The Invisible Hook: The Hidden Economics of Pirates. Princeton, NJ: Princeton University Press.
Locke, John. 1959. An Essay Concerning Human Understanding. 2 vols. New York: Dover Books.