The Logic of Love: A Natural Theory of Morality

This article presents an objective, naturalistic, scientific theory of morality. It is presented as an answer to the religious argument that there would be no objective morality without God and the equally fallacious secular argument that there is no objective morality at all. It is based on the same fundamental principles that have guided modern physicists to discover the unified laws of nature. To understand it, we first must review the essential nature of science and the historical trajectory that has led to the modern unified theories.

Objectivity, Symmetry, and Invariance

The essence of science is objectivity and the essence of objectivity is invariance under transformation. Harvard philosopher Robert Nozick explained this in his article Invariance and Objectivity where he describes the nature of objective facts or truths as follows:

1. First, an objective fact is accessible from different angles. It can be repeated by the same sense (sight, touch, etc.) at different times, it can be repeated by different senses of one observer, and by different observers. Different laboratories can replicate the phenomenon.
2. The second mark of an objective truth, related to the first, is that there is or can be intersubjective agreement about it.
3. The third feature concerns independence. If p is an objective truth, then it holds independently of people’s beliefs, desires, hopes, and observations or measurements that p.
4. An objective fact is invariant under various transformations. It is this invariance that constitutes something as an objective truth and it underlies and explains the first three features.

Nozick unified and grounded our concept of objectivity by explaining all its features in terms of a single concept – invariance under transformation. This commonsensical definition is the very root of why we believe there is an “objective world” independent of ourselves. We pick up an object, rotate it, look at it under different light, tap on it. We show it to others and ask what they see. Some properties remain invariant no matter how we or others investigate it; we call those properties objective facts.

Nozick’s definition of objectivity coincides exactly with the mathematical definition of symmetry. A geometrical object is symmetric with respect to a given transformation if its shape remains unchanged. The two most obvious symmetries are reflection and rotation. An object with bilateral symmetry looks the same when reflected in a mirror. An object with rotational symmetry looks the same when rotated through a given angle. For example, the appearance of a square remains invariant when it is rotated by 90^o. A circle is the most symmetric of all two dimensional objects because it can be rotated through any angle without variation.

Symmetry principles have recently become the fundamental unifying concept of physics, as noted by theoretical physicist and Nobel laureate Steven Weinberg:

Countless physicists have chimed in with similar observations. For example, Christopher Martin, in his article On Continuous Symmetries in the Foundation of Physics says this:

To understand the profound significance of these statements, we need to briefly review the history of physics.

Unification and Symmetry: The Historical Trajectory of Science

Scientific theories are designed to give a comprehensive explanation of a body of facts in terms of a few elementary principles. Successful theories reveal the underlying unity of apparently diverse phenomena. A Theory of Everything, often called the Holy Grail of physics, would give a fully unified explanation of all physical phenomena within a single theoretical framework based on a small set of axioms. If found, it would be a solution to the sixth of the twenty-three unsolved problems listed by mathematician David Hilbert in 1900. He suggested that physics should be axiomatized much as Euclid established the theory of Geometry on five axioms in his Elements (ca. 300 BCE). Isaac Newton made the first great step towards solving Hilbert’s sixth problem when he laid the axiomatic foundation of Classical Mechanics in his Three Laws of Motion:

1. An object remains at rest or moves in a straight line with constant velocity v unless acted on by a force F.
2. The force F is equal to the rate of the change in momentum (mv). For a body of constant mass m, the acceleration a is related to the force F by the equation F = ma.
3. For every action caused by force F there is an equal and opposite reaction given by –F.

Maxwell’s Equations

These three simple laws (principles, axioms) unified our understanding of the motion of objects, enabling us to both explain and predict related facts. But there were other phenomena such as light, electricity, and magnetism that required their own independent explanations so physicists were stuck with four disparate theories: a theory of mechanics, a theory of light, a theory of electricity, and a theory of magnetism. This all changed in 1861 when James Clerk Maxwell unified the latter three in a single theory of Electromagnetism that required only four elegant and compact axiomatic equations. There now were only two theories that required unification – Electromagnetism and Newtonian Mechanics.

The unification of Newtonian Mechanics and Electromagnetism was a daunting problem because the two theories are invariant under different transformations that are not consistent with each other. They could not both be true without contradicting the definition of objectivity, the very heart of science. Newtonian Mechanics is invariant under Galilean transformations whereas Electromagnetism is invariant under Lorentz transformations. To resolve this problem, Einstein focused on the fact that the speed of light, c, was itself a constant (invariant) in Maxwell’s equations, and so concluded that it was Newtonian Mechanics that must be modified to be Lorentz invariant. The result was his Special Theory of Relativity which not only unified Mechanics and Electromagnetism, but also unified space and time into a single ontological unity – spacetime. In the words of Minkowski:

And of course the central equation of Einstein’s new theory, e = mc², revealed the underlying unity of energy and matter. This shows the power of symmetry principles: At a time time when most people were still traveling in horse and buggy, Einstein revolutionized our understanding of space, time, mechanical motion, and energy by revealing their unity based on symmetry. This harkens back to the Plato’s understanding of symmetry, which he said “creates the greatest unity possible” as noted in the introduction to Symmetries in Physics : Philosophical Reflections:

Harmony, unity, beauty, science, and objectivity are themselves all subsumed in the concept of symmetry. These qualitative concepts became quantitative in 1918 when Amalie Emma Noether published her theorem that proved that any symmetry of spacetime would have a corresponding conserved quantity. Suddenly all the conservation laws of physics such as conservation of linear momentum, angular momentum, and energy, were derived from first principles. Anthony Zee expressed his excitement at this discovery in his fabulous review of this topic called Fearful Symmetry:

Einstein used the same principles to unify our understanding of Gravity by extending his principle of relativity to include general covariance of the laws. Quantum physicists followed his lead and now all physics is based fundamentally on symmetry principles. Space prohibits further review. It suffices to note that the trajectory of physics has been one of discovering ever greater unity based upon symmetry. This is the same pattern that I follow in my theory of morality.

The Logic of Love: A Natural Moral Theory

The moral theory I propose is intended to be objective in the same sense as our theories of physics described above. Therefore we must begin, like Einstein, to see if there are any invariant moral principles. The answer is not long to find. If there is any invariant moral principle, it is the Golden Rule. Here are a few examples from all over the planet:

Now look at the principle itself – it is symmetric under an interchange of Self and Other! This means our search for invariance has led to a principle that is itself symmetric. If this isn’t the Holy Grail of Moral Theory, I don’t know what could be.

There is another invariant associated with morality: Love. A person with no love is a person with no morality. Furthermore, love is the “motive force” in all moral reasoning. This is most evident in the formulation of the Golden Rule attributed to Jesus, “Thou shalt love thy neighbor as thyself.” And what is the nature of love? It is closely related to, if not identical with, the concept of unity. It is a kind of symmetry. Thus we arrive at my objective moral theory which is based on two symmetrically related axioms and two ontologically primitive concepts: Self and Love:

1. Self Love: This is the axiom that a Self loves Self because Self is one by definition. A Self naturally desires its own well-being. For a Self to exist, it must be a unified integrated whole.
2. Moral Symmetry: A rational Self recognizes the Other as a Self like unto one’s own Self. Moral symmetry stems from Logic and Love. Love is the unity of Self and Other. Self Love is reconciled with Love of the Other through the symmetric logic of the Golden Rule. The principle of indifference implies that there is no justification to prefer Self over Other. This is the principle of moral symmetry, fairness, justice. All moral statements must be symmetric under an interchange of person A and person B.

The first axiom is analogous to Aristotle’s law of identity: A is A. Identity is necessarily unity and the simplest symmetry. The second axiom symmetrically relates Self and Other. Fairness and justice are the root of morality, so morality is  intrinsically objective, like a pair of scales. It is my assertion that these two axioms explain all our moral intuitions. Therefore, this theory is scientific in the sense that it can be falsified if we find moral intuitions that it contradicts or fails to explain. It is an objective, naturalistic, scientific theory of morality.

Both principles are founded in the most basic and universal moral intuitions shared by all humanity and any objection is immediately shown to violate one of the two principles. The Golden Rule (Reflective Love) stands above all other moral principles as explained by Professor R. M. MacIver in his article The Deep Beauty of the Golden Rule (provided online by Google Books):

There also is another approach that really gets to the heart of the matter. My argument is a “left brained” analytic approach to morality. The “right brained” holistic approach is much simpler. It subsumes both principles in a single concept – Universal Love for all sentient beings. This is an objective standard because any rational observer could, in principle, discern between what is or is not more loving. To refute this argument, it would have to be shown that people cannot objectively determine what is more loving. Put together, we have a “whole brained” approach to the understanding objective morality:

Despite its clarity, many theists will attempt to refute the analytic form of my argument because it defeats their moral argument for God. This is a great irony because the two principles were taught by Christ when he said “Thou shalt love thy neighbor as thyself” (Matthew 22:39). His statement includes both principles of Self-love and the Golden Rule, and is best described as Universal Love so it encompasses both forms of my argument. Another irony leaps out when Christians oppose the analytic form because they unwittingly imply that they lack love for others when they say that there would be no morality without God. They forget love – the first principle of morality – when they argue that morality is based on mere rules dictated by a god.

Some people may be confused by the first principle because they have been taught that self-love is contrary to love for others. Nothing could be further from the truth. On the contrary, loving others is impossible without self-love. American psychologist Erich Fromm eloquently explained this in his book The Art of Loving. He was a masterful logician of love. His book has been hailed as one of the most important of the Twentieth Century. Fifty-six years ago he isolated and articulated the two axioms of my objective theory of morality. I was thrilled to find his work after I had formulated my theory. Here is the relevant extract from his book (pg 58). He first clarifies the illogical conflation of self-love and selfishness, and then explains the Golden Rule:

Fromm hammered this point home on page 63 where he quoted Meister Eckhart as stating that absolute symmetry between Self and Other is required for true love, which is unity:

This is the logic of love. Our moral intuitions are fundamentally based on love for Self and Other modulated through the symmetric logic of the Golden Rule.

The Beatles got it right. All you need is love.