Introduction

1Before a designed reality exists, there is only a substrate and someone facing it. The substrate contains no space, since no metric has yet told any two of its states how far apart they are. Nothing in it changes, because no law has been written to govern change. Its memory holds values that mean nothing, and its processors cycle through operations that describe nothing.

2Whoever sits before such a system occupies a position no engineer, architect, physician, or legislator in history has occupied. Each of them worked inside a world whose deepest rules were settled long before they were born. Builders of cathedrals took gravity as a given and shaped their vaults to stand against it. Painters received light from the sun, with its particular spectrum and its way of scattering in air, and made their art within its possibilities. Lawgivers wrote statutes for bodies that tire, bleed, age, and die, without ever having to choose any of those facts.

3A designer at the empty substrate inherits none of these givens. Every quantity that earlier makers treated as the fixed frame of their work becomes a variable awaiting a value. The decisions that settle those values fall into an order, since each early choice narrows the space in which later choices can be made. So the designer has to begin somewhere, with a first decision that everything built afterward will inherit.

4For nearly all of history this scene belonged to theology and to speculative fiction. Over the past few decades, several lines of research have moved it toward engineering. Physicists using lattice quantum chromodynamics now derive the masses of the proton and neutron, and even the small difference between them, from the equations of the strong and electromagnetic interactions. Quantum chemists predict the structure and behavior of molecules and materials from the quantum mechanics of their electrons before anyone has made them in a laboratory. Machine learning has produced world models, networks trained on video and interaction that generate explorable environments frame by frame, keeping terrain, lighting, and objects coherent as a user moves through them. Researchers have begun publishing assessments of which artificial architectures satisfy the indicators proposed by leading scientific theories of consciousness, and at least one AI developer has launched a research program on the welfare of its own models. Each of these results remains partial. First-principles calculation grows ruinously expensive as the number of interacting particles increases. World models hold their coherence for minutes and obey a physics learned approximately from footage. Nobody can yet determine whether a given system feels anything.

5What turns these fragments into a near prospect is artificial superintelligence, a capability exceeding human performance across science and engineering, which many of the people building today’s systems expect within years. Such a system could design its own successors and the hardware they run on. It could also pursue research faster than any human institution, closing in years distances that human science would cross in centuries. A civilization equipped with it could plausibly command the computation and theory needed to sustain a coherent physics that bottoms out near the level of life, along with the minds living under it, before this century ends. The figures this book uses for cost and capability are deliberately conservative, and superintelligence is likely to find machines and methods that leave them far behind, though nothing it builds can escape the limits physics places on every machine. The forecast could fail in its timing or its premises, and consciousness may resist inquiry even by minds far greater than ours. Still, the probability is high enough to make the design of realities a practical question for people alive today. Its ethics have to be settled before the capacity arrives, because whatever habits of thought exist when building becomes possible will govern what gets built. Those ethics turn on one question, what someone able to design a reality owes the beings who will come to live in it.

6Our own universe arose without any designer anyone can identify, and every later reality would have to be built inside it. It can be called the primordial cosmos, since it stands at the head of whatever sequence of realities comes after it. The usual name for a world sustained by computation is “simulation,” a word that ordinarily means an imitation of something located elsewhere. Weather models, flight trainers, and economic forecasts represent their targets without instantiating them. The hurricane in a forecasting model floods no streets and drowns no one. Calling a designed reality a simulation imports that relation of copy to original, and with it a ranking in which the computational world becomes a lesser shadow of the primordial one. A designed reality need imitate nothing, and the people in it are no one’s shadows.

7Consider what actually holds inside a reality whose physics runs on a computational substrate and whose inhabitants are conscious. Pain there hurts whoever suffers it. A parent grieves a lost child with a grief wholly their own, friendships console, and a climber’s hands bleed on rock as surely as any hands have bled on granite. Whether that rock consists of quarks or of states in a memory register makes no difference to the one who bleeds. When we learned that our own matter is made of excitations in quantum fields, not a single wound in our world hurt less. Reality, for anyone whose life is at stake, is a matter of what a world does to and for the subjects within it. A world that sustains conscious lives possesses all the reality those lives require, and describing it as an imitation invites its mistreatment. A maker who thinks of a world as a model will feel licensed to pause it, edit it, run it for curiosity, and delete it, treating its inhabitants as figures in a representation when each of them is a subject with as full a claim to existence as the maker.

8The question of what is owed reaches the physics as a question about what the whole construction is for. The technical choices that crowd forward first, such as the number of spatial dimensions, the form of the fundamental equations, or the smallest unit the substrate will resolve, all presuppose an answer to it.

9Aristotle had a word for the art that answers such a question. Near the opening of the Nicomachean Ethics he observes that every craft and inquiry aims at some good, and that crafts form hierarchies. Bridle-making and the other trades that equip horses serve horsemanship, and horsemanship, along with every other military activity, serves generalship. The ends of the governing arts are more choiceworthy than the ends beneath them, since the lower ends are pursued for the sake of the higher.

10He calls the governing arts architectonic and the art at the summit of such a hierarchy the most architectonic of all, architektonikē in the fullest sense, a word formed from archi-, meaning chief or first, and tektōn, meaning builder or craftsman. An architektōn was the master builder on a Greek construction site, the person who held the plan of the whole and directed masons, carpenters, and metalworkers toward a purpose none of their individual skills could define. Aristotle gives this master role to politics, which decides which sciences a city should cultivate, who should learn them, and how far. Its end, the human good, contains the ends of all the arts it directs.

11Designing a reality stands in exactly that relation to the sciences it draws on. Particle physics, cosmology, thermodynamics, chemistry, biology, information theory, and the science of mind all contribute a competence the designer cannot do without. They answer questions about how to bring an effect about, and none of them can say which effects deserve to be brought about. The governing art orders them by the good of the beings who will live in the result. The physicist chooses a star’s spectrum with skin and eyes in mind, and the biologist builds the signaling of bodily damage with attention to how it will feel.

12Aristotle’s master art was also political in the ordinary sense, concerned with the shared life of many beings under common laws. The design of a reality is political in the most literal sense available. Its designer legislates at the level of physical law for a population that had no voice in drafting the laws it lives under.

13Commitment Conscious experience is the ground of…The question of what the construction is for finds its answer in that population. Conscious experience is the ground of all value. A universe of galaxies, symmetries, and exquisite laws in which nothing is ever felt by anyone contains nothing good or bad for anyone. Good and bad are always good and bad for some subject, and where no subject exists the terms find no purchase. Once a subject exists, its good reaches beyond its experiences to real relationships, knowledge of its world, and freedom from domination. Stars, laws, and structures matter through what they mean for beings able to experience them. Elegance, parsimony, and grandeur earn a place in the design by entering someone’s life, as beauty to a perceiver or as intelligibility to an inquirer. A designer who began elsewhere, holding that a reality exists to display mathematical beauty, to generate interesting phenomena, or to honor its maker, would accept a physics that tortures its inhabitants whenever the torment produced a pleasing enough equation or spectacle. The record of our own universe shows how easily an elegant physics coexists with immense suffering.

14Commitment Moral standing extends to every being…Commitment Functionalism is the book’s working hypothesis…Commitment Under uncertainty about which systems are…Placing the subject at the foundation also extends moral standing to every being organized so as to have experiences, whatever it is made of, whether it evolved or was designed, and however many layers of computation separate it from the primordial cosmos. That extension rests on a working hypothesis, that consciousness arises from the functional organization of a system and can therefore be realized in neurons, in silicon, or in the matter of a physics no one has yet written. The hypothesis could be mistaken. Under that uncertainty the sound policy is precaution, which treats any system that might be conscious as a possible subject.

15With subjects as the measure, each physical parameter becomes a decision about lives. Take the fine-structure constant, the dimensionless number near 1/137 that measures the strength of electromagnetism. Together with the electron’s mass, its value fixes how tightly nuclei hold their electrons, and therefore the energies of chemical bonds, which in our universe fall at a few electron volts. Photons of visible light carry energies of the same order. That coincidence of scale allows sunlight to drive photosynthesis and a single photon to twist a pigment molecule in the retina and produce sight.

16Ultraviolet photons from the same star carry only slightly more energy, enough to fuse adjacent bases in a strand of DNA into lesions that cells repair imperfectly. A fair-skinned child spends summer afternoons on a beach, and small errors accumulate in the cells of her shoulders. Forty years later a dermatologist finds a dark, irregular mark that has already spread to a lymph node. Her illness, her children’s fear, and the months of treatment run back through mutation, ultraviolet chemistry, and stellar spectra to a single number. The same number stands behind every leaf that turns sunlight into sugar and every eye that has ever seen a face.

17Commitment A designer who selects a value…Other laws and constants reach into lives just as directly. Gravity’s strength settles how hard a child lands when she falls from a tree. Nuclear stability governs how much radiation seeps from the ground beneath a village. The second law of thermodynamics drains heat from every warm body into colder surroundings, so a hiker lost on a winter ridge may not survive the night. So far as anyone can tell, the primordial cosmos arrived at its values through no intention, which leaves its harms without anyone we can hold responsible for them. If some intention did lie behind those values, it was one that gave little consideration to the beings who would suffer under them. A designer who selects a value knowing its consequences takes up responsibility for all of them. The melanoma downstream of a constant enters the same account as the harvests and sunsets the constant makes possible.

18Commitment Forced annihilation is among the gravest…Some 170,000 human beings die on an ordinary day in our world, most of them from aging and the diseases that accompany it. Those processes are rooted in an evolutionary history that rewarded reproduction early in life and stayed indifferent to whether anyone wished to go on living. Beneath that figure lies a far larger toll among other animals, killed by predators, parasites, starvation, cold, and age in numbers no census records. Forced annihilation is among the gravest harms a conscious being can suffer. It destroys the subject and with the subject every good that being might yet have had, including friendships, discoveries, and pleasures still ahead, along with the chance to repair what went wrong before. The harm grows with what remains to be lost, so it is greatest where the future taken away would have been long and good. The capacities that would make designed realities possible bear directly on that toll. A civilization that understands consciousness well enough to sustain it on a computational substrate could perhaps carry the minds of the dying into worlds built without aging, provided the passage is made in a way that preserves each mind as the same subject. The same science of bodies and minds could also bring aging to an end within the primordial cosmos itself.

19Philosophy ordinarily proceeds at the pace of journals and seminars, which suits questions that will keep. These questions run on a harsher clock. If designed realities can be built within this century, each year separating understanding from construction corresponds to more than sixty million human deaths and to animal deaths beyond reckoning, every one of them a subject ended without consent. The harm in these deaths lies in what they take from beings who never chose to give it up. Every being able to choose therefore remains free to decline continuation for themselves, which keeps opposition to death from hardening into a duty to exist.

20Yet a designer who builds in haste and errs will fill a world with beings who must live inside the error. The urgency that calls for speed calls equally for exactness, and answering it means accepting the slower pace that careful verification of every parameter requires.

21Exactness needs a standard to be exact against, and that standard is the argument of this book, which has to answer seven questions in roughly the order a designer meets them. The first asks what makes a world real and what makes it fit to be lived in, and the second asks what the machine beneath a world may spare and what it must carry in full. Next comes who can be trusted to write a world at all. After that the argument turns to standing, which belongs to every being with a point of view, whatever it is made of and however it began. A fifth question asks how the lives in a world are to be judged, and a sixth asks when anyone may bring a new being into existence and what is owed to the dying who already exist. The last concerns keeping a world once it runs, so that its people never live at the mercy of whoever holds its machine. Some of the answers have appeared already, among them that conscious experience grounds value, that standing follows experience wherever it occurs, and that anything which might feel is treated as a possible subject. These and all the rest are argued in the chapters where they do their work, and a reader who wants them in one place will find them gathered at the end of the book, each beside the chapter that earns it.

22All of this reasoning converges on someone who does not yet exist. Far downstream of the first decision, after the metric, the forces, the chemistry, and the slow work of biology have run their course, a being will open whatever senses the design has given them and find themselves where all those choices have led. That being will inherit every value set at the empty substrate without having been consulted about any of them. They will live inside those values as plainly as we live inside the gravity that holds us to the floor. Whatever ease or hardship the physics contains will arrive in their life as the way things are, in the texture of stone underfoot, the length of a day, how far a voice carries across open ground, and whether this life must someday end.

23What the designer owes that being has to be paid in advance, in the care taken over every parameter. By the time the being can feel the consequences of a choice, the choice will long since have become a fact of nature.

24The substrate is as empty as it was at the start, holding no distance, no change, and no one. Yet the designer facing it is no longer alone. Somewhere beyond the last equation, a being who has not begun to exist is already waiting on every question asked here, and will receive each answer as simply the world.