Morals, Metaphysics and Naturalism

There are many traffic law systems around the world, just as there exists different systems of moral law. Each of these systems is a composite incorporating various elements. Each element serves a specific function within the system. These elements include specific rules with defined exceptions, roles for various players given specific authorities and responsibilities, rewards and penalties for compliance and non-compliance with the rules. In this section, I will focus on the rule aspect of traffic and moral law systems. In Section 3, I will bring into consideration the other aspects of the moral law system. I will use the term 'law' and 'rule' interchangeably throughout this essay. If you the reader find one of these terms problematic, simply replace that term with the other.

In brief, my argument is as follows. Our system of moral laws is a system for regulating social behaviour. It bears similarity with another system for regulating road behaviour; our system of traffic laws. That we ought to obey traffic laws is no more mysterious than our obligation to obey moral laws. Just as the normative force of traffic laws requires no supernatural or non-natural grounding, likewise for our moral laws. My argument here draws out the following five features that traffic laws share with moral laws.

1. Traffic laws are normative.
2. Traffic laws are formulated by humans.
3. Traffic laws are enforced by humans.
4. Traffic laws serve a social purpose.
5. There is one (or more) optimal set of traffic laws.

The conclusion here is that just as all of these features of traffic laws are sufficiently explained naturally, analogously, all of the features of moral laws require no other-worldly metaphysical explanation.

Let me address each of these similarities in turn.

1. 1.
   Traffic laws are normative.

Traffic laws are action guiding. They provide a reason for driving according to certain constraints. Each locality's traffic code constitutes a set of norms for driving in that locality. Driving in Australia, for example, requires drivers to drive on the left-hand side of the road.

However we explain the force of the obligation to obey traffic rules, no recourse is made to a transcendental lawgiver or some mysterious metaphysical attribute of the universe. Whichever natural explanation we use to ground the normativity of road rules applies equally to the 'oughtness' of moral rules.

1. 2.
   Traffic laws are formulated by humans.

The content of traffic laws in the various localities was determined by human agents. Road speed limits and give-way priorities, for example, were handed down neither from on high nor discerned by interrogating the mysteries of the universe. Historical documents record the decisions of groups of people making the first road law conventions. Similarly, archaeology uncovers the first moral codes devised by ancient human societies around the world, such as the Egyptian 42 Laws of Maat, the Hittite Code of the Nesilim, the Babylonian Code of Hammurabi and the Jewish Law of Moses.

1. 3.
   Traffic laws are enforced by humans.

Each locality assigns and trains people in specific roles for specific enforcement purposes. Depending on the locality, these can include traffic infringement officer, traffic police officer and regular police officer. Punishments for infringement include a variety of human-enforced penalties, including fines, demerit points, forfeiture of licence and jail time.

Similarly, moral rules are enforced by a multiplicity of human agents, including judges, parents, teachers, and community and religious leaders. Adherence to the moral rules is encouraged using a variety of inducements and penalties. As with the enforcement of road rules, divine or other non-natural intervention is not a manifest feature of the enforcement regime.

1. 4.
   Traffic laws serve a social purpose.

Traffic control systems arose for the specific social purpose of maintaining safety and convenience. The first comprehensive set of road regulations appeared in England in 1835 with the Highway Act. Road laws resembling those of today appeared in 1931 with the Highway Code (see Ministry of Transport [1931]). They originated in response to the increasing frequency of accidents as more cars appeared on roads. The first traffic laws were introduced in the United States for that purpose in the early twentieth century (see, for example, Powers [2020]. The content of traffic laws is neither random nor arbitrary. Regulators design and modify traffic laws with the intention of either improving efficiency or safety or both.

Likewise, universally agreed moral laws serve to optimise individual and collective welfare. Permitting the torturing and killing of innocent people and allowing gratuitous stealing and lying would quickly lead to social disintegration, as those propounding a religious grounding for moral rules so often rightly point out.

1. 5.
   There is one (or more) optimal set of traffic laws.

There is a fact of the matter about whether, in a given locality, one proposed law better achieves the objectives of the traffic law system compared with another. There is at least one set of laws that optimally achieves the objectives of regulators and road users. In that sense, reasons are offered for adopting one law over another. None the less, there may be more than one optimal system. In some cases, adopting either one of two contrasting options will achieve the same objectives. For example, prescribing driving on the left- or right-hand side of the road may achieve the objectives of safety and efficiency equally well.

Similarly, moral laws understandably may differ in two different societies without undermining their purpose. For example, societies culturally and historically structured around children caring for their aged parents will place a more stringent moral expectation on children compared with societies that leave aged care largely to the state. In both the case of traffic laws and moral laws, variability of laws is expected naturally without detriment to either system. The content of both road laws and moral laws are not subject to whim or personal preference, as metaphysicians rightly emphasize. At the same time, a naturalist explanation for both systems adequately accounts for variations in content across time and place.

That completes my survey of the five key similarities between road rules and moral rules. If a naturalist account explains adequately the development, content and normativity of road rules (as it surely does), then we can equally eschew obscure metaphysical explanations for our system of moral rules. As I have tried to show here, both systems arose as a response to real human day-to-day needs as societies and their technologies increased in scope and complexity. The rules in both systems are devised and enforced without exception by human agents. Just as no spooky metaphysics is required to underwrite our obligation to obey road rules, likewise for moral rules. Finally, a naturalist account explains why both road rules and moral rules share basic features from epoch to epoch, region to region, while allowing for some variation for local historical and cultural factors.

No gods or other metaphysical elements are required for the explanation in both cases. Any move to introduce such non-natural concepts into the account is superfluous. (One example of this redundancy is the attempt to ground our moral responsibility to each other on the interconnectedness of everything in the universe—'we are all one'. When I ask the mystic how they justify the taking of antibiotics to cure them of a serious infection, the ideal of the oneness of all gives way to a mundane weighing of competing interests.)

An interlocutor could point out that there is one fundamental difference between traffic laws and moral laws that breaks the usefulness of my analogy. Traffic laws, they may insist, are restricted to regulating behaviour on the roads whereas moral laws apply to all behaviour without restriction. I do not think this difference raises a problem with my argument. In fact, I think this difference in scope of application is a strength of my analogy. These features of the traffic rules system that I point out can be easily generalized to all human behaviours. That's the lesson that my analogy draws.

Within the realm of all human behaviours, there is nothing magical or mysterious about behaviours off the road compared with those on the road. All social interactions—not just on-road behaviours—benefit from co-operation and co-ordination. A system that provides confidence that a fellow citizen will fulfil a contract is advantageous to all citizens, just as a system that gives assurance that a fellow motorist will drive on the right side of the road is a benefit to all motorists. I will say more on this universalist aspect of moral laws when I deal with this and other objections to my analogy in Section 5. But first, I want to fill out the picture a bit more on the other important analogous elements in the traffic rules and moral rules systems.

Copyright © 2026 Leslie Allan