Natural Laws Are Moral Rules for Choosing Sides in Conflicts by Impartial Rules of Action: DeScioli and Locke

Here's the Abstract for Peter DeScioli's article--"On the Origin of Laws by Natural Selection"--in the May 2023 issue of Evolution and Human Behavior (vol. 44, pp. 195-209):

Humans are lawmakers like we are toolmakers. Why do humans make so many laws? Here we examine the structure of laws to look for clues about how humans use them in evolutionary competition. We will see that laws are messages with a distinct combination of ideas. Laws are similar to threats, but critical differences show that they have a different function. Instead, the structure of laws matches moral rules, revealing that laws derive from moral judgment. Moral judgment evolved as a strategy for choosing sides in conflicts by impartial rules of action—rather than by hierarchy or faction. For this purpose, humans can create endless laws to govern nearly any action. However, as prolific lawmakers, humans produce a confusion of contradictory laws, giving rise to a perpetual battle to control the laws. To illustrate, we visit some of the major conflicts over laws of violence, property, sex, faction, and power.

DeScioli does not realize that he has restated John Locke's account of laws as moral rules rooted in the law of nature that emerged in the human state of nature, which was the environment of evolutionary adaptedness in which human nature was shaped.  In the foraging societies in Locke's state of nature, the laws of nature are moral rules for choosing sides in conflicts by impartial rules of action, which are enforced by the weak teaming up to compel the strong by their coordinated punishment of wrongdoers.  This agrees with DeScioli's reasoning, but he does not understand that his explanation of "the origin of laws by natural selection" is implicitly an explanation of Lockean natural law grounded in the Darwinian evolution of human nature.  This is clear in one of the two sentences where DeScioli explicitly refers to natural law:  "the origin and stability of official laws depend on the natural laws composed by our moral judgment, backed by the coordinated attacks they unleash" (201).

WHAT ARE LAWS?

To understand laws, DeScioli suggests, we can study their expression in language and ask what ideas are behind the words.  He begins with an example of a law against murder:

Whoever is guilty of murder in the first degree shall be punished by death or by imprisonment for life (196).

Whoever is guilty of murder suggests the idea of impartiality, because "the law applies to everyone who murders, whether family, friend, ally, or king."  The phrase is guilty implies that the person must be proven guilty with evidence.

Murder in the first degree stipulates that the person has murdered deliberately, knowingly, and with malice, which alludes to ideas of mental states such as intention, knowing, and purposeful planning.

The phrase shall be punished indicates that the law will be enforced by a necessary punishment that no murderer should expect to escape.

That the punishment is by death or by imprisonment for life suggests the idea that the penalty should be proportionate to the crime:  since a murderer takes a life, he should be punished by the loss of his life--a life for a life.

"We therefore find within one law a wealth of ideas.  They include indefinite people, actions, intentions, truth, impartiality, possibility, necessity, punishment, and proportion."

To illustrate how we see "the same ideas in law after law," DeScioli considers a sample of ten laws from Exodus in the King James Bible.  He can then conclude:

In general, we find the same themes and variations in the laws of society after society: the spoken laws of foragers, the Laws of Eshnunna and the Code of Hammurabi from ancient Sumer, the Tang Code from medieval China, the common law of England compiled in Blackstone’s Commentaries, the Constitution of the United States, the Universal Declaration of Human Rights, mundane traffic codes, and so on.

In each case, we find rules about a general person who can, cannot, or must perform a specific action, and the rules are enforced by punishment. Humans combine these universal elements with variable actions to make infinite laws (197)

These "universal elements" should be identified as "natural law."  DeScioli actually refers in one passage to "the natural laws composed by our moral judgment" (201).  But he does not reflect on how his evolutionary reasoning about law might be connected to the tradition of natural law jurisprudence.

That he begins with the law against murder as paradigmatic for law in general is an idea that he shares with natural law thinking.  The law against murder is the most prominent law of violence because in violent conflicts human beings are naturally exposed to life-threatening attacks, and they have a natural desire for self-preservation that supports their natural right to life.  

"Thou shalt not kill.  Thus proclaims the most unanimous and iconic of moral laws.  Anyone who is mortal supports it.  If only all laws were so agreeable" (202).

But then DeScioli recognizes that of course there are exceptions to the no-killing rule.  We may kill in self-defense, in defense of the lives of others, in defense of our country in war, or to punish a wrongdoer.  So now he no longer defends a Kantian categorical imperative of no killing with no exceptions as a model of moral judgment.  

Instead of a Kantian morality of categorical imperatives, DeScioli implicitly assumes a natural law morality of hypothetical imperatives, which means that if we want to protect human life, then we must punish murder as unjustified killing, but killing in defense of life is justified.  People obey the natural law only as long as most people see it as beneficial to themselves.  "As each person simulates the effects," DeScioli observes, "they conclude that protection against murder is more valuable than the freedom to murder" (202).

That all law rests on a hypothetical imperative is implicit in what DeScioli identifies as the conditional form of all law: "If anyone [action], then they will be punished" (198).  If you do not want to be punished for breaking the law, then you ought to obey the law.

Locke explains the primacy of punishment in the law of murder as grounded in human nature by saying that in the state of nature, everyone has the "executive power of the law of nature," which is the natural power to punish those who violate the law of nature; and this includes the right of every man in the state of nature to kill a murderer, both to deter others from murdering, and to secure everyone from unjust violence.  Upon this is grounded "the great Law of Nature, Who so sheddeth Man's Blood, by Man shall his Blood be shed" (Second Treatise [ST], 11).  Thus, Locke quotes a divine command in Genesis 9:6 and equates it with a law of nature.  

Similarly, when DeScioli quotes ten divine laws from Exodus, he says nothing about divine authority, and thus implies that these laws can arise naturally from the human mind; and that they can be enforced by the natural human propensity to punish those who violate natural law, because human beings can see that the natural law benefits them (196-97).  Even the Old Testament suggests this, because Moses repeatedly declared that if the Israelites obeyed his laws, they and their children would survive and prosper in competition with other groups (Deuteronomy 4:40, 6:1-3, 11:8-9, 20, 23:9-14, 25:11-16).  Even Biblical laws are hypothetical imperatives: if you want to survive and prosper, then you must obey these laws.

WHAT ARE LAWS FOR?

Having seen the ideas in the mind that constitute laws, DeScioli suggests, we next need to ask what laws are for.  We are asking about the evolutionary functions of law.  To answer that question, we need to consider the whole history of the human species beginning about 300,000 years ago, when our human ancestors lived as nomadic hunter-gatherers, before the invention of writing and agriculture, because it was it was during that longest period of human history that natural selection shaped the human mind.  If we looked only at written laws, we would see only the last few thousand years, which is less than 1% of our history.

Our human ancestors lived in foraging societies with a few hundred people who knew each other well. In foraging societies, the laws are spoken, preserved as customs, and enforced by a close community with gossip, blame, and punishment. Like the laws we discussed earlier, the laws of foragers govern countless actions including murder, theft, marriage, sex, diet, work, sacrifice, sorcery, and many more. Foraging societies, then, are the natural habitat where the ability to make laws evolved, so there we will find what laws are for (197).

This "natural habitat" for the evolution of the human ability to make laws is what Locke called the "state of nature," in which for most of human history, our human ancestors lived in small foraging societies governed by spoken laws enforced by the whole community that constituted the "law of nature."  Locke learned this from his study of hundreds of works of travel literature by Europeans who had explored the New World.  From this, Locke inferred that "in the beginning, all the world was America," and that the foraging societies in America were "still a Pattern of the first Ages in Asia and Europe" (ST, 49, 108).  

In these first human societies, Locke saw what Christopher Boehm identified as egalitarian hierarchy:  some individuals have higher status than others and exercise some leadership, but subordinates use sanctions--such as ridicule, disobedience, ostracism, or execution--to restrain politically ambitious individuals, those with special learned or innate propensities to dominate.  In every society, there will be leaders in some form. But an egalitarian society will allow only a moderate degree of leadership checked by popular resistance to domination expressed as spoken laws that protect the weak against the strong.

DeScioli sees here an evolutionary transition from despotic hierarchies enforced by animal threats to egalitarian hierarchies enforced by human laws.  Animals use threats to reduce the harms of fighting.  A stronger animal will threaten to attack a weaker opponent if the opponent does not retreat from food, territory, or a sexual mate claimed by the threatener.  The threatener benefits from persuading the opponent to retreat without a costly fight.  The opponent also benefits from not fighting a costly battle that he would lose anyway.  Animals also fight over dominance because having high rank in a dominance hierarchy gives an animal control over valuable resources, and dominant animals use threats to persuade subordinate animals to be submissive.

DeScioli notes that laws might look like threats because they are similar in their conditional form:  if someone does something wrong, he will be punished.  A threat could be: if you come closer, then I will punish you.  A law could be:  if you commit murder, then you will be punished.  But despite this similarity in form, DeScioli sees differences between threats and laws.

The conditional form for threats is: If [event], then I will punish you.  The conditional form for laws is:  If anyone [action], then they will be punished.  For threats, the person addressed is you.  For laws, the person addressed is anyone.  For threats, the condition is an event.  For laws, the condition is an action.  For threats, the attacker is the threatener.  For laws, the attacker is everyone.  For threats, the punishment is coercive.  For laws, the punishment is proportionate.

There are four fundamental differences.  First, while threats are directed to a particular person (you), laws are directed to whosoever meets the stipulated condition (everyone).

A second difference is that while in threats, the threatener plans to attack, laws warn that everyone in the community plans to attack.  In this way, laws have an impartiality that threats do not have: we expect everyone to want the wrongdoer punished.  In some foraging societies, offenders can be punished by their own kin.  In modern societies, we assign legal specialists (such as police, judges, and prison guards) to carry out the punishment of lawbreakers, but these specialists are understood to be acting as representatives of the whole community.

A third difference between threats and laws is made clear in foraging societies, where, as DeScioli observes, "the strong compel the weak by threats, while the weak compel the strong by laws" (199).  "In foraging societies, the weaker members, not the superiors, commonly make and enforce the laws.  Foragers use laws against dominant aggressors to suppress their ambitions for power."  The many weaker individuals check the power of the few stronger individuals because the weaker are more numerous, and they can form coalitions of the majority, so that the weak team up against the strong.  Relatively few animal species form coalitions, and for those who do, it's usually coalitions of kin groups competing against other kin groups.  Chimpanzees can form more flexible coalitions that can sometimes challenge dominant individuals.  Christopher Boehm and Richard Wrangham have identified this primate propensity for forming coalitions of the weak to overthrow stronger dominant individuals as the evolutionary precursor to the evolved human capacity for forming coalitions of the majority that enforce laws that constrain the power of the strong to compel the weak by threats.

It is hard to see this, however, as DeScioli explains, if we consider only the history of written laws.  The invention of writing about 5,000 years ago, in places like ancient Mesopotamia, emerged in agricultural societies with extreme hierarchies of kingly power, and thus the first written laws (like the Laws of Hammurabi) often depicted the king receiving the laws from a deity.  Written laws were issued by a few stronger superiors to compel the obedience of the many weaker subordinates.  And to a large extent, these written laws were actually "threats disguised as laws to make them appear more just" (199).

DeScioli observes:

This historical confound has caused much confusion, such as the classic dilemma about whether a king or god at the top of the hierarchy must follow the laws too. A threatener is not bound to obey their own threat, yet we sense that laws bind everyone. We resolve the confusion once we expand our view to include the foraging societies that comprise 99% of human history. Among foragers, a few superiors do not use laws to compel the many, but rather the many use laws to compel the few. Laws are made and enforced by everyone in the community not only the superiors at the top. So yes, kings and gods must follow laws too (199).

We need to see how laws originally evolved in foraging societies as spoken laws by which the weak compelled the strong, in contrast to the written laws in the first despotic kingships that compelled the weak to obey the strong.

This is what Locke does by showing how the laws of nature first arose in the state of nature to protect the liberty of all men against the aggression of the strong, and how the emergence of absolute monarchies allowed a powerful few to pervert the laws so that they could rule tyrannically unconstrained by law, which rightly provokes the many to rebellion (ST, 20, 93).

The final, and most fundamental difference, between threats and laws is that while threats are coercive rules of force that can be seen in many animal species, laws are moral rules of authority that are unique to human beings.  This difference becomes blurred when tyrannical rulers express their threats as laws:

"We again need to distinguish genuine laws from fake laws that are really threats in disguise.  As we have seen, threats, whether spoken or written in statutes, have parts that differ from laws, so we can distinguish threats in disguise from genuine laws.  Recall too that threats are easy to understand: a king who writes a statute to punish dissenters uses the same strategy as an alpha baboon who charges at rivals.  In contrast, we seek to understand the strange parts of laws, including their use of actions, truth, impartiality, and proportion.  A precious clue is that moral rules share the very same peculiarities" (199).

Locke makes the same distinction between "genuine laws" and "fake laws that are really threats in disguise" in describing absolute monarchies where the appeal to the impartial rule of law is denied:

"Where an appeal to the Law, and constituted Judges lies open, but the remedy is den'd by a manifest perverting of Justice, and a barefaced wresting of the Laws, to protect or indemnifie the violence or injuries of some Men, or Party of Men, there it is hard to imagine any thing but a State of War.  For wherever violence is used, and injury done, though by hands appointed to administer Justice, it is still violence and injury, however colour'd with the Name, Pretences, or Forms of Law, the end whereof being to protect and redress the innocent, by an unbiassed application of it, to all who are under it; wherever that is not bona fide done, War is made upon the Sufferers, who having no appeal on Earth to right them, they are left to the only remedy in such Cases, an appeal to Heaven" (ST, 20).

"Appeal to Heaven" is Locke's phrase for when people take up arms in rebellion against an oppressive government.

This distinction between "genuine laws" and "fake laws" is expressed in the traditional natural law teaching that unjust laws are not really laws (see, for example, Thomas Aquinas, Summa Theologica, I-II, q. 95, a. 2; q. 96, a. 4).  This distinction also denies the claim of legal positivists like John Austin who say that law is nothing more than command backed by threat.

If, as DeScioli says, "laws and moral rules are one and the same," and this is certainly true for foragers, then laws and moral rules should have the same evolutionary purpose, which he identifies as choosing sides in conflicts.  When conflicts break out in forager societies, people need to choose sides.  DeScioli identifies three strategies for doing this.

One strategy is to support the fighter with greater status in the dominance hierarchy.  If most people do this, they can make a convincing threat that forces the subordinate fighter to back down.  This can restore the peace, but in strengthening the hierarchy, it increases the danger of a tyranny in which the strong oppress the weak.

A second strategy for choosing sides is to support one's own allies against their opponents.  This creates powerful coalitions that can check the power of potential tyrants in the dominance hierarchy.  But this also creates the danger of factional conflicts between the coalitions.

To avoid the dangers of both tyrants and factions, DeScioli suggests, natural selection favored moral judgment as a strategy for choosing sides in conflicts by impartial rules of action.  Moral judgment is the uniquely human capacity of the human mind for creating rules of right and wrong and then applying those rules to conflicts so that people can choose the right side over the wrong side.  If most people do this, and if they share the same rules and evidence, they will choose the same side in conflicts.  The majority of the people in a society can then coordinate their choices through impartial moral rules without following the hierarchy, which checks the power of the dominants, and without strengthening rival factions.

And yet, as DeScioli indicates, moral judgment never completely replaces hierarchy and coalitions as strategies for managing conflicts.  The best strategy varies according to the circumstances of different individuals and groups.  Communities also vary as to which strategy is customary for different kinds of conflict.

These laws of moral judgment arise in nomadic foraging societies without formal governmental institutions as customary unwritten laws, which are what Locke calls "the law of nature."  With the establishment of formal governmental structures in settled agricultural societies, some of these natural laws were formally enacted as stipulated written laws, which DeScioli calls "official laws," and which Locke identifies as the transition from the state of nature to "political society" (ST, 86-94).

DeScioli explains:

These rules, amplified by writing, ritual, and government, we call the law. The official laws include only a fraction of the moral rules in a community, those that officials have found practical and expedient to enforce. This fact gives the common impression that morality and law are different. Indeed, to be precise, written laws are a subset of moral rules that have been selected, refined, and elevated to serve the ends of lawmakers. Nonetheless, law and morality come from the same origin in the mind, because moral judgment produces the stock of rules from which official laws are chosen. Moreover, citizens use their moral judgment to assess the official laws and to coordinate attacks against the government when its laws stray too far from the community’s moral code. Thus, both the origin and stability of official laws depend on the natural laws composed by our moral judgment, backed by the coordinated attacks they unleash. 

The game of choosing sides explains why written laws are so powerful, in fact more powerful than the leaders and officials who enforce them. For a prominent law can summon not only police and soldiers but also immense battalions of civilians who choose sides by following the law’s beacon. The game of coordination explains too why the official laws can be suddenly overrun by rebels. Public events may change the most prominent strategy to a rule that turns citizens against the government. For instance, everyone could see a scandal of political corruption and condemn it together, which then makes the prohibition against corruption more prominent than the obligation to obey the authorities, spurring a violent rebellion widely perceived as morally justified. By a synchrony of moral outrage, people perceive that the natural law against corruption supersedes the official law against violent revolt. Likewise, a public spectacle could make hierarchy or faction the most prominent strategy for taking sides, overriding law and morality altogether. For example, a dictator who prominently executes dissenters could make many citizens conclude that hierarchy supersedes moral judgment in that society (201-202).

Notice here DeScioli's implicit confirmation of Lockean natural law thinking--the two references to natural law, the claim that official law depends on the natural law that arose in the foraging state of nature, and the recognition that people have a natural right to rebel against a government that violates natural law (ST, 12, 135, 223-43).

All of this shows how a modern evolutionary explanation of the origin of laws by natural selection supports a Darwinian understanding of Lockean liberalism.

FROM IDENTITY RULES TO GENERAL RULES

We might think that DeScioli's one big mistake is his assumption that throughout the history of law, laws have been understood as impartial rules of action.  He thus ignores the fact that the history of law shows a transition from the illiberal conception of laws as identity rules to the liberal conception of laws as general rules.  Henry Sumner Maine called this the move from status to contract.  

In medieval and early modern Europe, for example, the laws were applied differently based on one's social identity.  In many parts of Europe, the nobility either did not pay many taxes or were assessed at a lower rate of taxation than were commoners.  Under the criminal law, the punishments for nobles were less severe than for commoners.  Jews, Protestants, and Catholics faced different treatment by the law.

But DeScioli might respond by saying that "laws as identity rules" are what he calls "fake laws that are really threats in disguise" that support powerful factional coalitions--such as the "nobility"--against "commoners."  Originally, in prehistoric forager societies, the many (the commoners) enforced impartial customary laws against dominant individuals and the ambitious few.  But then with the emergence of centralized states, kings and nobles were able to enforce fake laws that were really threats to suppress the many.  In a few more liberal societies (like ancient Athens), laws as impartial rules could restrain to some degree the dominant power of the one and the few, which restored to some extent the egalitarian liberty of the foraging state of nature.

Then in modern liberal states, the laws are understood as general rules that apply impartially to all regardless of differences in social status, which goes even farther towards approximating the equal liberty of the evolutionary state of nature.  These are what Douglass North and his colleagues called "open access societies."  Laws as general rules are crucial for the liberal conception of the state as securing individual freedom and social cooperation.  This liberal understanding of the laws as impartial rules of action approximates the law of nature as it arose in the evolutionary state of nature.

Laws Are Moral Ideas Created by the Human Mind and Expressed in Language: DeScioli and Locke

 The May 2023 issue of Evolution and Human Behavior (volume 44, number 3) is a special issue on "Evolution, Justice, and the Law."  One of the best articles is "On the Origin of Laws by Natural Selection" (pages 195-209) by Peter DeScioli.  Although he says nothing about John Locke, almost everything he says confirms Locke's explanation of morality and law as based on the law of nature that arose in the state of nature, which evolutionary psychologists identify as the human "environment of evolutionary adaptation."  Here I begin a series of posts pointing out the parallels between Locke and DeScioli with links to some of my posts on the evolutionary psychology of Lockean liberalism.

Although we might assume that laws are what is written in law books, DeScioli observes, this is mistaken for two reasons.  Laws must appear as ideas in the mind before they appear as written in a book.  And for most of human evolutionary history, over 300,000 years, before the invention of writing, human beings lived in hunter-gatherer societies with spoken laws.

The critical point here is that laws are created by the human mind as moral ideas that then are expressed in spoken or written language.  This mental capacity for creating the moral ideas of law is unique to human beings.  As Frans de Waal has explained, of the three levels of human morality, other primates show the first two levels--morality enforced through moral sentiments and social pressure--but not the third--the morality of moral judgment.

Similarly, Locke saw that human beings were the only animals with the rational capacity for creating the moral ideas of law.  "For, were there a monkey, or any other creature, to be found that had the use of reason to such a degree, as to be able to understand general ideas, he would no doubt be subject to law," and in that sense, Locke observed, that rational monkey would be a "moral man" (ECHU, III.11.16).

Darwin made the same point in The Descent of Man: "any animal whatever, endowed with well-marked social instincts, the parental and filial affections being here included, would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become as well, or nearly as well developed, as in man" (2004, 120-21).

Moral ideas in the mind arise from a symbolic inheritance system that is uniquely human because it shows the qualitative leap that defines our humanity as based on our capacity for symbolic thought and communication. Other animals can communicate through signs. But only human beings can communicate through symbols. The evolution of human language was crucial for the evolution of symbolism. Symbolic systems allow us to think about abstractions that have little to do with concrete, immediate experiences. Symbolic systems allow human beings to construct a shared imagined reality. These symbolic constructions are often fictional and future-oriented. Art, religion, science, and philosophy are all manifestations of human symbolic evolution.  Moral rules and laws are also products of this human mental capacity for symbolic thought and language.

The mind's symbolic creation of moral ideas and law corresponds to what Locke calls "mixed modes" in the mind.  Locke makes it clear that in the state of nature, when human beings lived in bands of hunter-gatherers, there was no formal government, but there were human social institutions--particularly, marriage, families, private property, economic exchange, and social norms of moral conduct that Locke calls "the law of nature." This was the first human society that was created by informal consent--collective recognition or acceptance--through language, and language itself was a social creation in which certain sounds were given symbolic meaning by a "tacit consent" (ECHU, II.2).  But this society was not a political society, because there was not yet any consent to a formal government or legal system (First Treatise, pars. 86-93; Second Treatise, pars. 6-14, 25-35, 77-90). 

Language creates society.  Locke explained in the Essay Concerning Human Understanding that social institutions were created by human beings through the language of mixed modes for use in social intercourse (II.2.22; II.28.2-4; II.31.3; III.1.1, III.2.8; III.5).

According to Locke in the Essay, all our ideas originate in experience, either in experience of the external world, which we have through sensation, or in experience of our own thinking and wishing, which we have through reflection.  We form our simple ideas in our minds directly from these experiences.  We can then form complex ideas by combining and comparing simple ideas, and we can form general ideas by abstracting one idea from others with which it is associated.  Thus, all human thought arises either as an impression from experience or as a modification of such impressions by some faculty of the mind.

Locke distinguishes the complex ideas of substances from complex ideas of modes and relations.  Complex ideas of substances are combinations of simple ideas that represent particular things that exist by themselves, for example, man, sheep, army, and gold.  Modes are complex ideas that do not contain any representation of anything existing by itself; rather, modes are ideas conceived as modifications of simple ideas.  Simple modes are combinations of a single simple idea, for example, space and duration.  Mixed modes combine several different simple ideas, for example, triangle, gratitude, obligation, and murder.  Ideas of relations are a special kind of mixed mode that arises by comparing one idea with another, for example, father, whiter, cause and effect.

Mixed modes are important for social and political thought, because most of the words used in theology, ethics, law, and politics are mixed modes.  Locke's examples of mixed modes include adultery, incest, murder, parricide, justice, gratitude, glory, and ambition.

Locke emphasizes the arbitrariness of mixed modes.  The ideas of mixed modes are "made very arbitrarily, made without patterns, or reference to any real existence.  Wherein they differ from those of substances, which carry with them the supposition of some real being, from which they are taken, and to which they are conformable.  But, in its complex ideas of mixed modes, the mind takes a liberty not to follow the existence of things exactly."  Mixed modes are "the workmanship of the mind" (III.5.3-4). 

This is the same arbitrariness that John Searle sees in institutional facts that exist only because we think they exist and say that they exist.  Searle declares: "God can create light by saying 'Let there be light!'  Well, we cannot create light, but we have a similar remarkable capacity.  We can create boundaries, kings, and corporations by saying something equivalent to 'Let this be a boundary!' 'Let the oldest son be the king!'  'Let there be a corporation.'"

But since both Searle and Locke stress the arbitrariness with which human beings freely create their social norms by collective consent through speech, we have to wonder whether this denies that there is any natural foundation or standard for judging our moral ideas.  And if so, wouldn't this contradict Locke's claim that there is a natural law knowable by natural human reason and Searle's claim that human rights are rooted in human nature, which suggest a natural standard rather than arbitrary creation?

Locke says that while mixed modes are made "very arbitrarily," they are not made "without reason" or "at random" (III.5.3, 6-7).  Although our moral ideas are not copied from nature, they are made by human beings for the purpose of communicating standards of conduct that facilitate human social life; and the requirements of such a life are shaped by the natural desires and inclinations of human beings.  The ultimate natural standard for judging social norms is whether they satisfy the natural human pursuit of happiness (I.2.3; III.21.42-73).  In that way, human nature does set standards for our moral ideas.

So, for example, if human beings say that intentionally killing an innocent human being is murder, and murder shall be punished, but killing a sheep is not murder, this distinction is not simply discovered by just looking at human beings killing one another and killing sheep.  This moral distinction is made by human beings to serve the natural desire of human beings to preserve their lives against attack and to punish those that threaten them (III.5.5-6; FT, 86-88; ST, 7-11).  And if we distinguish the killing of a father or mother as worse than killing others, it's because of the different heinousness of the crime that demands a distinct punishment that fits the crime (III.5.7).  Similarly, if we create the idea of an incest taboo, it's because human beings naturally express moral disgust in response to incest, although there will be cultural variation in how incest is defined based on variable kinship systems.

In this view of moral principles and laws as inventions of the human mind, we see an empiricist ethics of moral anthropology as opposed to the transcendentalist ethics of moral cosmology.  A moral anthropology sees morality as dependent on the human mind and the symbolic world that it creates.  A moral cosmology, by contrast, sees morality as independent of the human mind in conforming to the cosmic normativity of a cosmic God, a cosmic Nature, or a cosmic Reason.

The ethical transcendentalists assume that a moral anthropology makes morality and law fictional by seeing them as arbitrary inventions of the human mind.  But the ethical empiricists argue that morality and law are not arbitrary or illusory as long as they are grounded in an enduring, although not eternal, human nature: morality and law are neither objective truths about the universe nor subjective illusions of individual fancies but intersubjective symbolic principles to which human beings have consented.

As DeScioli and Locke suggest, the moral laws of homicide illustrate this cognitive reality of moral rules and laws as the means by which human beings choose sides in conflicts.  I will explain that in the next post.

Peter DeScioli's Response: The Kantian Denial of the Thomistic Distinction Between Intended and Unintended Killing

Peter DeScioli has sent me some responses to my previous post.  He has given me permission to quote them here:

I just skimmed your article and have just one clarification for now: We did not intend to draw on Kant as an explanation or theory of moral judgment. We use "Kantian" in a purely descriptive sense to mean that people's judgments resist utilitarian tradeoffs in dilemmas like the footbridge trolley problem. Our use of "Kantian" is synonymous with "absolutist", "non-consequentialist", "deontological", "taboo" in Tetlock's sense of resisting tradeoffs, and other synonyms in the moral psychology literature. So just as describing moral judgment as "absolutist" does not appeal to something transcendental, we did not intend "Kantian" to do so. Kant is simply an iconic example of rigid moral judgment focused on prohibited actions and resistant to tradeoffs, and similarly we refer to "categorical imperatives" as a descriptive label of moral psychology, rather than as an appeal to Kant's theories. 

Let me also point you to the passage below from DeScioli 2016 which you cited. It illustrates how I use Kantian as a descriptive label for categorical judgments in contrast to utilitarian judgments which I here label as Vulcan, using Spock from Star Trek to represent utilitarian judgments. I argue that humans are "hybrid Vulcan-Kantians," meaning we have both forms of judgment, as seen in the footbridge and switch versions of the trolley problem. Our view is that the Vulcan judgments come from cognitive systems designed for altruism, while Kantian judgments come from cognitive systems for choosing sides. 

DeScioli has said that "Immanuel Kant would argue . . . that when humans face this dilemma, they should not kill one to save five because there is an inviolable moral rule against killing that cannot be broken regardless of the consequences" (Kurzban et al. 2012, 323).  So, DeScioli suggests, in the footbridge version of the trolley problem, most people show a Kantian morality in refusing to kill the fat man because they believe there is an "inviolable moral rule against killing" regardless of the good "intended outcome" (saving five lives) of the killing.  But in the switch version of the trolley problem, most people show a utilitarian morality that justifies killing one person when the "intended outcome" is good--saving five lives.

DeScioli sees an unresolvable contradiction between two kinds of moral rules--killing is always wrong versus killing is wrong except when the "intended outcome" is good.

But as DeScioli has indicated, John Mikhail's research offers a plausible way to resolve this contradiction by seeing the Thomistic Principle of Double Effect as part of the evolutionary moral psychology of human beings.  By seeing that one action can have two effects--one that is intended and another that is foreseen but unintended--we can see that the outcomes or consequences in the footbridge and switch cases of the trolly problem are not the same.  In both cases, one person is killed to save five people.  But in the footbridge case, both the saving of the five people and the killing of one person are intended.  While in the switch case, the saving of the five is intended, but the killing of one is not.

DeScioli recognizes this Thomistic distinction between intended and unintended killing when he considers the laws of violence.  "Thou shalt not kill . . . proclaims the most unanimous and iconic of moral laws" (DeScioli 2023, 202).  Here then is the Kantian categorical imperative--no killing regardless of the consequences.  "But there are of course exceptions," DeScioli says.  We allow killing to punish a wrongdoer, killing in self-defense, and the killing of enemy combatants in war.  But doesn't that deny the Kantian categorical imperative of no killing regardless of the consequences and with no exceptions?

As Aquinas indicated, these exceptions to the no killing rule depend on the distinction between intended and unintended killing.  One may kill an aggressor to save one's life or the lives of others, but only as long as the killing is not the directly intended effect.  If the aggressor retreats or surrenders, and thus gives up the threat to life, we cannot rightly kill him.  To kill him in that situation would be an intended killing, which is wrong.  This requires that we judge the circumstances and the consequences of our actions.

This Thomistic principle of double effect in cases of killing is clearly illustrated in the laws of just war.  Combatants may kill enemy combatants in war to remove their threat to life.  But once the enemy combatants surrender, we cannot kill them without being charged with intentional murder.  We may directly target enemy combatants for attack, but we may not directly target noncombatants, even though noncombatants are often killed as an unintended side-effect of attacks directed at combatants.  So, for example, we can condemn the directly intended terror bombing of Germany and Japan in World War II by the allies as unjust.

This illustrates DeScioli's primary argument "on the origin of laws by natural selection"--that moral rules and laws are for choosing sides in conflicts.  So when someone threatens to kill someone, and his threatened victim argues that this is morally wrong, we can take the side of the victim by agreeing to moral rules or laws that prohibit unjustified killing.  But strangely DeScioli denies that people taking the same side in a conflict is a form of cooperation.  Equally strange is that DeScioli does not see how the rule of justified killing--such as killing in self-defense or killing to save the lives of others--denies the Kantian absolute rule of no killing with no exceptions.

Consider this scenario at the opening of one of his articles:

"Imagine you are alone on a desert island when a hulking man says to hand over your food supplies or he will kill you.  You protest that his threats are morally wrong.  How much protection could your moral judgment really provide?  If you had to choose, would you defend yourself with a hand axe or moral arguments?  Now imagine instead that there are fifty people on the island.  In this case, morality might actually be the better weapon: a persuasive moral argument could rally dozens of armed defenders to your side" (DeScioli 2016, 23).

Persuading dozens of people to give you armed defense against the threats of a murderer sounds like cooperation to me!  Indeed, this is exactly how social cooperation emerges in Locke's state of nature when people agree to formulate the law of nature for resolving conflicts and to punish the violators of that natural law.  Moreover, recruiting "armed defenders to your side" must violate the Kantian absolute rule of no killing--not even in self defense.

I will say more about this in another post.