Glossary
- architektonikē
-
The governing art, the one that directs other arts toward an end none of them could set for itself. The word comes from the Greek for chief builder, and the book uses it for the art of designing a world, ordered by the good of the beings who will live in it.
In the text
…architektonikē in the fullest sense, a word formed from archi-, meaning chief or first, and tektōn, meaning builder or craftsman.
Introduction, The First Decision, ¶ 10
The governing art orders them by the good of the beings who will live in the result.
- basic claims
-
The two negative claims every subject holds equally, whatever its degree of consciousness. They are the claim not to be made to suffer and the claim not to be destroyed against its interest.
In the text
Every subject stands equal in its basic claims, which are negative, the claim not to be made to suffer and the claim not to be destroyed against its interest, whatever its degree of consciousness.
See also duties of aid and moral standing
- the carpenter’s world
-
The designed world the book returns to as its example, the world of the third table. A carpenter there cut a table from a tree that grew under a star whose spectrum was chosen, and a boy skips stones at the edge of a lake.
In the text
Imagine now a third table. It stands in a room in a world that someone designed. A carpenter there cut it from a tree that grew in soil formed under a star whose spectrum was chosen.
Chapter 1, The Third Table, ¶ 4
In the carpenter’s world, the world of the third table, a boy stands at the edge of a lake toward evening.
- checkpoint
-
A saved copy of the complete state of a world at a given moment, from which the world can later be restored.
In the text
A machine can save the complete state of a world at a given moment, a checkpoint from which the world can later be restored.
See also restoration and rollback
- computationally sustained reality
-
A reality whose laws are carried out by a computational substrate. The term names the medium that carries a world’s laws, so a world can be designed, computationally sustained, or both.
In the text
A designed reality is one whose laws and initial conditions were chosen by a designer, and a computationally sustained reality is one whose laws are carried out by a computational substrate, the first term concerning where a world’s laws came from and the second the medium that carries them.
Chapter 1, Words for the Work, ¶ 89
See also designed reality and substrate
- deep world
-
A world whose physics goes down far enough for life to arise from chemistry. Every body in it costs as much to carry as the matter it is made of.
In the text
A deep world lets life arise from chemistry and makes every body as costly as the matter it is made of.
Chapter 2, The Depth of a World, ¶ 14
See also depth, shallow world, and far horizon
- deferral
-
Postponing the computing of a region and computing it in full later, one of the economies a machine can use. Within a protected region it is permitted and saves nothing.
In the text
The first is deferral, which postpones computing a region and later computes it in full.
See also summary
- depth
-
How far down a world’s physics goes, meaning the finest level it resolves. The designer chooses where the physics bottoms out, and that choice, more than any other, sets what the world costs to carry.
In the text
What it costs to carry the boy’s evening depends above all on how deep the world goes, meaning the finest level its physics resolves.
Chapter 2, The Depth of a World, ¶ 7
The designer decides where the world’s physics bottoms out.
Chapter 2, The Depth of a World, ¶ 9
See also deep world, shallow world, level, floor, and richness
- designed reality
-
A reality whose laws and initial conditions were chosen by a designer. The term says where a world’s laws came from.
In the text
A designed reality is one whose laws and initial conditions were chosen by a designer, and a computationally sustained reality is one whose laws are carried out by a computational substrate, the first term concerning where a world’s laws came from and the second the medium that carries them.
Chapter 1, Words for the Work, ¶ 89
See also computationally sustained reality and primordial cosmos
- designer
-
Whoever answers for a world’s laws and initial conditions, and for what they do to the lives lived under them. The first designers are likely to be composites of people, institutions, and machines.
In the text
The designer answers for a world’s laws and initial conditions and for what they do to the lives lived under them.
See also keeper
- domination
-
Living at the mercy of another’s will, whether or not the other ever interferes, as Philip Pettit describes it in Republicanism (1997).
In the text
…domination, the condition Philip Pettit describes in Republicanism (1997) as living at the mercy of another’s will, whether or not the other ever interferes.
- duties of aid
-
Positive duties owed because a being is in need and someone is able to help, with rescue first among them, along with relieving suffering one did not cause and providing what a being lacks. They vary with two things only, the probability that the being feels and what it stands to lose.
In the text
The positive duties that vary are duties of aid, owed because a being is in need and someone is able to help, with rescue first among them, along with the relief of suffering one did not cause and the provision of what a being lacks.
See also basic claims
- emulation
-
A mind computed at the grain of its function, at the level of its neurons and synapses rather than molecule by molecule, as an immigrant carried in from the primordial cosmos would be. It is still the mind it was only if that grain carries what consciousness depends on.
In the text
…emulated minds, such as immigrants carried in from the primordial cosmos and lodged in bodies of the world, provided a mind computed at a functional grain is still the mind it was.
Chapter 2, The Depth of a World, ¶ 13
See also grain and immigrants
- far horizon
-
The farther of the book’s two forecasts, in which deep worlds grow their own chemistry and life. Its designer would be a civilization able to command a star’s output with nearly reversible machines and to keep worlds running far slower than their keepers live.
In the text
On the far horizon, where deep worlds grow their own chemistry and life, the designer would be a civilization able to command a star’s output with nearly reversible machines and to sustain institutions that keep worlds running far slower than their keepers live.
Chapter 3, Who Will Write a World, ¶ 5
See also near horizon and deep world
- fault
-
An error in the machine that shows up inside a world, such as a flipped bit. Inside the world it has no natural cause, because nothing in the world’s laws produced it.
In the text
Inside a world, a fault has no natural cause, because nothing in the world’s laws produced it.
See also checkpoint
- finite list
-
One possible floor for a world, a finite list of fundamental things with nothing underneath.
In the text
One possibility is a finite list of fundamental things with nothing underneath.
See also floor
- fit to be lived in
-
Said of a reality that has the three marks of reality and also the capacities for publicity and participation. The subjects who live in such a reality are its inhabitants.
In the text
A reality that bears the capacities for publicity and participation as well as the three marks of reality is fit to be lived in, and the subjects who actually live in one are its inhabitants.
Chapter 1, Words for the Work, ¶ 90
See also marks of reality, publicity and participation, and inhabitants
- floor
-
The level where a world’s physics bottoms out, chosen by its designer. It might be a finite list of fundamental things, a lattice, or a regress that keeps yielding structure, and whatever the inhabitants’ science finally finds will be that choice.
In the text
The questions will continue until their instruments either reach a level with nothing beneath it or keep finding structure beneath every level they reach. Whatever they find will be the floor the designer chose.
See also depth, finite list, and sequential floor
- forgetful machine
-
A machine that erases information as it computes, as ordinary computers do. It pays at least Landauer’s price for every operation, however slowly it runs.
In the text
Ordinary computers forget constantly and in practice spend many orders of magnitude more energy per operation than Landauer’s limit.
Chapter 2, Ceilings and Costs, ¶ 21
A forgetful machine pays Landauer’s price for every operation of those years, however slowly it runs.
Chapter 2, Ceilings and Costs, ¶ 23
See also Landauer’s limit and reversible machine
- grain
-
The level of detail at which something is computed, such as the grain of molecules or the grain of a mind’s function. The finer the grain, the higher the cost, and no one yet knows the grain at which consciousness depends on physical detail.
In the text
Described at the grain of molecules, the same lake becomes a finite problem.
Chapter 2, The Depth of a World, ¶ 8
It would be safe only if the designer knew the grain at which consciousness depends on the physical details beneath it.
Chapter 2, The Depth of a World, ¶ 16
See also depth, emulation, and the middle path
- halo
-
The finely computed world around a creature, reaching as far as it can sense and moving with it, while the world beyond can be summarized. It thins with distance.
In the text
Around every fish there is therefore a halo of finely computed water reaching as far as the fish can sense, moving with it as it swims.
See also summary and protected region
- immigrants
-
Inhabitants who came to a world from another reality, such as minds carried in from the primordial cosmos.
In the text
Natives have never lived anywhere else, whether they arose there or were built there, and immigrants came to it from another reality.
Chapter 1, Words for the Work, ¶ 90
See also natives, emulation, and the passage
- inhabitants
-
The subjects who actually live in a world fit to be lived in, natives and immigrants alike, in bodies of its matter or, where the world allows it, without one.
In the text
…the subjects who actually live in one are its inhabitants.
Chapter 1, Words for the Work, ¶ 90
Both live in bodies of its matter or, where a world allows it, without one.
Chapter 1, Words for the Work, ¶ 90
See also natives, immigrants, and visitors
- keeper
-
Whoever answers for the machine that carries a world’s laws, for its fidelity to them, and for its custody over time.
In the text
The keeper answers for the machine that carries those laws, for its fidelity to them, and for its custody over time.
See also designer
- Landauer’s limit
-
The least heat that erasing one bit of information must release, proportional to the temperature of the surroundings and about 3 × 10 to the power −21 joules at room temperature. It is a price on forgetting.
In the text
…erasing a bit of information must release a minimum amount of heat, proportional to the temperature of the surroundings, which comes at room temperature to about 3 × 10 to the power −21 joules. The price attaches to forgetting.
Chapter 2, Ceilings and Costs, ¶ 21
See also forgetful machine and reversible machine
- level
-
A layer of organization at which things act on one another by their own laws, such as the level of molecules or the level of life.
In the text
…a level is a layer of organization at which things act on one another by their own laws.
- line of protection
-
The probability of feeling at and above which a system is treated as a subject in full. The book sets it at a credence of one in ten.
In the text
The rule keeps Birch’s structure and adds a stated threshold, the line of protection, a probability of feeling at and above which a system is treated as a subject in full, modeled on his sentience candidate.
Chapter 5, The Precautionary Rule, ¶ 31
The line of protection sits at a credence of one in ten.
Chapter 5, The Line of Protection, ¶ 36
See also protected region, precautionary rule, and two errors
- marks of reality
-
The three features that make a lawful order of events a reality at all. Its events have causal powers of their own, it holds together whatever any mind in it believes, wishes, or attends to, and it is counterfactually robust, meaning it would have answered as its laws require had any earlier state been otherwise.
In the text
To the first question, what makes something a reality at all, the answer is a lawful order of events bearing three marks.
Chapter 1, What a Reality Is, ¶ 56
Its events have causal powers of their own.
Chapter 1, What a Reality Is, ¶ 57
It holds together independently of the beliefs, wishes, and attention of any mind it contains.
Chapter 1, What a Reality Is, ¶ 57
It is counterfactually robust.
Chapter 1, What a Reality Is, ¶ 57
See also fit to be lived in
- the middle path
-
Building a deep world and then computing its natives’ brains at the cheaper grain of their function. The book rejects it, since the saving would be taken from subjects who never agreed to bear it, while a shallow world built openly is allowed.
In the text
The designer could build a deep world, let chemistry and life run at full depth everywhere, and then compute the brains of natives at the cheaper grain of their function, as though each skull held an emulation in place of matter.
Chapter 2, The Depth of a World, ¶ 16
What they may not do is build a deep world and then quietly make its people shallow, because a saving taken on a subject is a harm done to someone who never agreed to bear it.
Chapter 2, The Depth of a World, ¶ 16
See also deep world, shallow world, and grain
- model and simulation
-
Names for a use of a system. A system is a model whenever someone reads its states as standing for a target elsewhere, whatever its own structure. The book avoids calling a computed world a simulation, since the word suggests an imitation of something located elsewhere.
In the text
The usual name for a world sustained by computation is “simulation,” a word that ordinarily means an imitation of something located elsewhere.
Introduction, The First Decision, ¶ 6
The words “model” and “simulation” stay in this vocabulary as names for a use, since a system is a model whenever someone reads its states as standing for a target elsewhere, whatever its own structure may be.
- moral standing
-
A being’s claim to moral consideration in its own right. The book extends it 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.
In the text
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.
Introduction, The First Decision, ¶ 14
See also possible subject and basic claims
- native physics
-
The laws closest to a machine’s own operations and cheapest for it to carry. A designer under budget pressure feels a steady pull toward the machine’s native physics.
In the text
Every machine therefore has what might be called a native physics, the set of laws closest to its own operations and cheapest for it to carry.
Chapter 2, Ceilings and Costs, ¶ 31
See also physics
- natives
-
Inhabitants who have never lived anywhere else, with bodies made from the designed world’s own materials, whether they arose there or were built there.
In the text
…natives, beings whose bodies are made from the materials of the designed world and who have never lived anywhere else.
Chapter 1, The Senses of a Word, ¶ 11
Natives have never lived anywhere else, whether they arose there or were built there, and immigrants came to it from another reality.
Chapter 1, Words for the Work, ¶ 90
See also immigrants and inhabitants
- near horizon
-
The nearer of the book’s two forecasts, in which worlds bottom out near the level of life and minds are carried at the grain of their function. Its likeliest first designer is a laboratory or company directing artificial systems.
In the text
On the near horizon, where worlds bottom out near the level of life and minds are carried at the grain of their function, …
Chapter 3, Who Will Write a World, ¶ 5
See also far horizon and shallow world
- the passage
-
Carrying the mind of a dying person into a designed world in a way that preserves it as the same subject.
In the text
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.
Introduction, The First Decision, ¶ 18
See also immigrants and emulation
- pause
-
A halt in the computing of a world, after which it may resume. Its inhabitants would notice nothing, and from inside, a pause cannot be told from an ending until the world resumes.
In the text
From inside, a pause and an ending are indistinguishable until the moment of resumption, which in an ending never arrives.
Chapter 1, The Objection from Multiplicity, ¶ 83
See also rollback and substrate time and world time
- physics
-
The laws a reality obeys together with the things those laws govern, as distinct from the substrate that carries them.
In the text
A reality’s physics is the set of laws it obeys together with the entities those laws govern, as distinct from the substrate beneath them, …
Chapter 1, Words for the Work, ¶ 89
See also level, substrate, and native physics
- possible subject
-
A system that might be conscious. Under the precautionary rule it is treated as possibly a subject, with care scaled to the chance that it feels and to what it stands to lose.
In the text
Under that uncertainty the sound policy is precaution, which treats any system that might be conscious as a possible subject.
Introduction, The First Decision, ¶ 14
See also precautionary rule
- precautionary rule
-
The book’s policy under uncertainty about consciousness. Any system that might be a subject is treated as possibly one, with care scaled to the probability that it feels and to what it stands to lose.
In the text
Under uncertainty, the asymmetry between these errors settles the policy, which the rest of this book calls the precautionary rule. Any system that might be a subject is to be treated as possibly one, with care scaled to the probability that it feels and to what it stands to lose.
Chapter 1, What a Reality Is, ¶ 67
See also two errors, possible subject, and line of protection
- primordial cosmos
-
Our own universe, seen as the first in whatever sequence of realities may be built from within it. Its substrate is unknown.
In the text
It can be called the primordial cosmos, since it stands at the head of whatever sequence of realities comes after it.
Introduction, The First Decision, ¶ 6
The primordial cosmos is our universe, first in the sequence of realities that may be built from within it.
Chapter 1, Words for the Work, ¶ 89
See also designed reality and substrate
- protected region
-
The region drawn generously around every creature whose capacity to feel is left seriously open by the best available evidence, since no one can yet tell for certain which creatures feel. Whatever lies in it is computed in full whenever it is computed, and computed once, without speculative runs that are later erased.
In the text
No one can yet tell for certain which creatures feel, so the region this rule protects, the protected region, is drawn generously, around every creature whose capacity to feel is left seriously open by the best available evidence.
See also line of protection and summary
- publicity and participation
-
The two capacities a reality needs, besides the marks of reality, to be fit to be lived in. Publicity lets many subjects meet in it, encounter the same objects, and check their perceptions against one another. Participation lets it host beings made of its matter, whose actions change it and who are changed by it in turn.
In the text
The first is publicity, the capacity of a reality to be public, so that many subjects could meet within it, encounter the same objects, and check their perceptions against one another. The second is participation, the capacity to host participants embedded within it, beings made of its matter whose actions change it and who are changed by it in turn.
Chapter 1, What a Reality Is, ¶ 59
See also fit to be lived in
- restoration
-
Recovering what a fault destroyed, using a checkpoint. Done the simple way it rewinds the world and erases everything lived since, so the book asks keepers to restore what was lost into the present.
In the text
Checkpoints are the root of restoration.
…a keeper who uses checkpoints must learn to restore what was lost into the present instead of returning the present to the past.
See also checkpoint and rollback
- reversible machine
-
A machine whose every step can be undone, so that nothing is erased and Landauer’s price need not be paid on each step. Running it more slowly costs less energy, which makes energy and waiting a single currency.
In the text
Charles Bennett showed in 1973 that computation can be made logically reversible, with every step undoable, so that nothing is ever erased and Landauer’s price need not be paid on each step.
Chapter 2, Ceilings and Costs, ¶ 24
Energy and waiting then become a single currency.
Chapter 2, Ceilings and Costs, ¶ 24
See also forgetful machine, Landauer’s limit, and substrate time and world time
- richness
-
What a world comes to hold that no one specified, such as the languages its natives form, the music they compose, and the friendships they choose. It grows from the laws working on the initial conditions over time, as it did in the primordial cosmos, so it belongs to what grew.
In the text
The primordial cosmos acquired its richness in exactly this way, from a short list of laws working on a set of initial conditions over a very long time. A designed world is man-made in its foundations in the sense that a forest grown from planted seed is man-made, and its richness belongs to what grew.
See also depth
- rollback
-
Discarding computed work and computing it again, as machines do when a guess about another part proves wrong. Where a region holds a subject, a rollback erases experiences that were computed and computes different ones in their place.
In the text
Optimistic methods have each part compute ahead on its best guess and roll back when a message arrives showing that the guess was wrong, discarding the work done since and computing it again.
Chapter 2, Many Machines, Two Clocks, ¶ 67
When an optimistic machine rolls back a region that contains a subject, it erases experiences that were computed and computes different ones in their place.
Chapter 2, Many Machines, Two Clocks, ¶ 68
See also checkpoint and restoration
- sequential floor
-
The limit set by operations that must follow one another, which no quantity of hardware can pass, because such operations cannot be spread across more machines. It caps how fast any machine can carry a world.
In the text
No quantity of hardware passes that sequential floor, since operations that must follow one another cannot be spread across more machines.
Chapter 2, Ceilings and Costs, ¶ 23
See also floor
- shallow world
-
A world whose physics stops at about the level of life, so that bodies are built from coarse units arranged to do what neurons do, with nothing finer underneath. Minds are cheap to carry there, though such a world may never produce them by itself.
In the text
…the natives of a world that is shallow beneath the level of life, whose bodies are built from coarse units arranged to do what neurons do, with nothing finer underneath.
Chapter 2, The Depth of a World, ¶ 13
A world shallow beneath life makes minds cheap, and it may never produce them.
Chapter 2, The Depth of a World, ¶ 14
See also depth, deep world, and near horizon
- substrate
-
The system on which a reality’s physics runs, such as the machine that carries a designed world.
In the text
The substrate is that medium, the system on which a reality’s physics runs, and for the primordial cosmos it is unknown.
Chapter 1, Words for the Work, ¶ 89
See also physics and substrate time and world time
- substrate time and world time
-
The two clocks of a computed world. Substrate time is the time of the primordial cosmos, in which the machine runs, and world time is the time the inhabitants live. The two can run at very different rates.
In the text
Substrate time is the time of the primordial cosmos, in which the machine runs, and world time is the time the inhabitants live.
Chapter 2, Many Machines, Two Clocks, ¶ 69
See also pause and reversible machine
- summary
-
Replacing the full detail of a region with a coarse description of it, as statistical mechanics describes a gas by its temperature and pressure without following a single molecule. It is not allowed within a protected region.
In the text
The second is summary, which replaces the full detail of a region with a coarse description of it, the way statistical mechanics describes a gas by its temperature and pressure without following a single molecule.
See also deferral, halo, and protected region
- two errors
-
The two ways a designer can be wrong about a world’s inhabitants. Believing an empty world inhabited is a grave mistake, and treating an inhabited world as empty is a graver one, since it falls on beings able to suffer. That difference sets the direction in which protection should err.
In the text
A designer who built such a world while believing it inhabited would have made a grave mistake. The opposite mistake would be graver, because it would fall on beings able to suffer.
Chapter 1, What a Reality Is, ¶ 67
The asymmetry between the two errors sets the direction in which the line of protection should err.
Chapter 5, The Precautionary Rule, ¶ 35
See also precautionary rule and line of protection
- visitors
-
Those who experience a world through an interface while their minds run elsewhere. They are not its inhabitants.
In the text
Visitors experience a world through an interface while their minds run elsewhere, and they are not its inhabitants.
Chapter 1, Words for the Work, ¶ 90
See also inhabitants
- working hypothesis
-
The book’s assumption about consciousness, functionalism. It holds that a system’s experience is fixed by its organization at the level where organization matters, whatever material carries it, so that consciousness can be realized in neurons, in silicon, or in the matter of a physics no one has yet written.
In the text
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.
Introduction, The First Decision, ¶ 14
On that basis functionalism is the best working hypothesis available, the claim that a system’s experience is fixed by its organization at the level where organization matters, whatever material carries it.
Chapter 5, The Working Hypothesis, ¶ 11
See also grain