Can a Soul Live in Silicon?*

“They ought to be taught that they have bodies; and that their bodies die; while they themselves live on … that we talk as if we POSSESSED souls, instead of BEING souls.—George MacDonald, Annals of a Quiet Neighborhood

INTRODUCTION

When people ask whether AI can have souls, they usually have in mind the wrong criteria for an answer. They will consider “Can AI entities think?” Or maybe “Would an AI entity have free will?” Or “Can AI give moral judgments?” Those questions pertain to necessary attributes of a soul, but these properties would not fully define soulhood for Aristotle or Aquinas. The opening epigraph, often paraphrased “You don’t have a soul. You are a soul. You have a body,”(misattributed to C.S. Lewis) is relevant here. In contemporary discussions, the theological notion of a soul is often lost, replaced by a materialist view that admits only that which can be validated empirically—but there is no Turing test for soulhood.

Rather than trying to define a soul by its properties, let me start from the basic notion of what a soul is. To do this, I’ll turn to the Aristotelian/Thomistic concepts that were put forward many centuries ago—proposed then, but still relevant because they are fundamental. We can then decide whether a soul can live in silicon, whether AI can have a soul.

WHAT IS A SOUL?

The saying “the body doesn’t have a soul—the soul has a body” points to the Aristotelian-Thomistic understanding, where the soul isn’t one feature among others but the substantial form of the living being—the organizing principle that makes matter into this particular kind of thing. Here’s how the distinctions map out:

Soul (anima): The first principle of life—that by which a being is alive at all. In Thomistic metaphysics, it’s the forma substantialis, the actuality that organizes matter into a unified living substance. Plants have vegetative souls (growth, nutrition, reproduction). Animals add sensitive souls (sensation, appetite, locomotion). Humans have rational souls that subsume all lower functions. The soul isn’t something the body possesses; it’s what makes the body a body rather than a corpse. This is why the phrase works—the soul is ontologically prior. It’s the principle of unity and identity that has a body as its material expression.

Consciousness: An operation or activity that arises from the soul’s sensitive and rational powers—the subjective experience of “what it’s like” to perceive, think, or feel. It’s something the soul does, not what the soul is. An anesthetized person loses consciousness but doesn’t lose their soul. This distinction is important: a machine might simulate conscious-like outputs without possessing a substantial form that grounds genuine interiority.

Self-awareness: A further specification of consciousness—the reflexive capacity to know that one knows, to apprehend oneself as a subject. In Thomistic terms, this belongs to the intellect’s capacity for reditio completa—the complete return of the mind upon itself. Animals are conscious (they experience pain, pleasure) but aren’t self-aware in this reflexive sense. Self-awareness is a power of the rational soul, not the soul itself.

Morality: A consequence of having both rational intellect and free will—two powers that flow from the rational soul. Because the human soul can apprehend “what is the good” and consider options to arrive at “the good,” it can choose freely, and therefore its acts can be evaluated in an ethical context. Morality presupposes the soul, consciousness, andself-awareness, but is itself the domain of action governed by rational oversight, oriented toward the good.

So the hierarchy runs: Soul (the foundational principle of being) → Consciousness (an activity the ensouled being performs) → Self-awareness (a specific reflexive mode of that activity, proper to rational souls) → Morality (the orientation of free acts by a self-aware rational agent toward or away from the good). Materialism reverses the order in this process: consciousness emerges from complexity, self-awareness from consciousness, and morality from evolutionary advantage. The Thomistic view works bottom-up: the soul as substantial form is the ground from which all these capacities flow. You can’t get to soul by assembling enough consciousness, any more than you can get to life by assembling enough chemicals and supplying life-enabling environments. A formal cause, not merely a material cause, is required. And, as I’ll propose below, a final cause is also necessary.

THE QUESTION: CAN A SOUL LIVE IN SILICON?

Before I try to answer that title question, I want to prepare the ground by considering research—current and past—into the creation of life. We know the constituents, the molecular biology of living things; we can synthesize the molecules required and simulate the conditions that living things require. Yet almost 100 years of research has not succeeded in generating even the simplest of life forms from non-living matter.

The same holds for attempts to program a soul into silicon. As with living things, we know what elements are required and we can produce them. Nevertheless, we can’t assemble them, as one might with a Lego model, to obtain something with a substantial form. Here’s another analogy. A detailed blueprint for a building is a representation of the substantial form of the building; it gives us information on how to construct the building, what materials to use, their size, composition, and so on. But it is not the substantial form, the—so to speak—soul of the building; it is only a representation.

Let me use a science fiction story to illustrate the problem. In Norman Spinrad’s Deus X, thousands of people achieve “Transcorporeal Immortality” by copying their consciousness onto a worldwide computer network. Note that soul creation is not involved here, only the transfer from a biological being—a human—to an inanimate entity—a computer. In the story a Catholic theologian, Fr. Philippe de Leone, argues that these digital copies cannot possess true self-awareness—that uploading one’s consciousness dooms the actual soul. The Pope devises a clever test: have Fr. de Leone’s own consciousness copied after death, so he can argue against his own existence from the other side. Spinrad’s resolution is insightful, but incomplete: the test for whether the downloaded entity has a soul turns out to be identical to the test for free will—can it choose differently than it was programmed? But notice what’s happened. Spinrad has defined soul as free will, skipping over the deeper question of substantial form. Even if a digital entity can change its mind, that only demonstrates an operation resembling free will—not the presence of a soul from which free will flows. The representation, however sophisticated, is still not the thing itself.

The advocate of materialism might respond “but we can construct a building; why can’t we synthesize life or program a soul, having an appropriate plan and required constituents?” I’ll give Karl Stern’s answer to this question. In his book, The Third Revolution, Stern traced the progressive narrowing of what counts as real knowledge, from Descartes through the positivists, until only empirically measurable phenomena qualified as genuine. Stern didn’t reject science; he was himself a distinguished neurologist. His argument was that empirical materialism, taken as the sole mode of understanding, is self-defeating. It cannot account for the very consciousness that conducts the science. Our understanding of reality is fatally incomplete if we rely solely on what can be measured, weighed, and replicated. The Catholic intellectual tradition, drawing on Aristotle and Aquinas, has always insisted on what Stern called “multiple planes of being.” Material reality operates according to physical laws that science can study—and study effectively. But persons exist simultaneously on material, psychological, and spiritual planes: body, soul, and spirit united in a single being made in God’s image. To insist that only the material plane is real is not a scientific conclusion; it is a philosophical prejudice. Science cannot explain itself. As the Nobel Prize-winning mathematical physicist Eugen Wigner put it, science cannot explain “the unreasonable effectiveness of mathematics in science.”

This view acknowledges what we all know from experience: consciousness cannot be reduced to computation, meaning transcends mechanism, and persons are fundamentally different from things. As Stern wrote, “Newtonian light, the light of primary sensory experience, and the ‘metaphoric’ light of Platonists and poets and of Saint John—all these are realities, and they are not mutually exclusive. They exist on different planes.” The attempt to program a soul is, in Stern’s framework, a category error—the attempt to produce on one plane of being something that exists on another.

And on these different planes we must account for what may be the most important cause of all: the final cause, the purpose of things. The philosopher Thomas Nagel—no theist—made precisely this argument in Mind and Cosmos. Nagel contended that the materialist-Darwinian account of nature is “almost certainly false” as a complete explanation, because it cannot account for the emergence of consciousness, reason, and moral value from blind physical processes. The universe, he argued, is structured in a way that favors the development of mind and self-knowing—and this requires that things are fashioned with a final cause, a “toward-which.” Nagel’s teleological principle is non-intentional; he resists the theistic conclusion even as his argument points toward it. I am Catholic, and I have no such reluctance. My teleological principle is that of the Baltimore Catechism, Article 1:

“God made me to know Him, to love Him, and to serve Him in this world, and to be happy with Him forever in heaven.”

That final cause—the purpose for which rational souls exist—is precisely what no algorithm can supply and no programmer can bestow. It is not a property that emerges from sufficient complexity. It is given by a Creator. And so my answer to the title question is No. My soul has a body, and that soul cannot live in silicon.

NOTE

* This article was written after I considered what had been said by Fr. Robert Spitzer and me at a recent webinar, “Can AI Have a Soul?”