Short Answers

Lecture 10A: Chalmers “The Matrix as Metaphysics”

Continuity versus Equivalence

• Several students asked me in office hours about continuity. It prompted me to make the following qualification:

• Equivalence is: • Qualitative Identity

• At a time

• To say two things are equivalent is to say they are alike • Either in some respect (e.g. two people of equivalent height)

• Or absolutely (they are duplicates)

• Continuity is: • Non-accidental similarity and/or relatedness

• Over time

• To say A at time T is continuous with B at time T1 is to say that they are related and similar.

• If a certain kind of continuity amounts to persistence (e.g. if brain continuity is persistence) then to say they are continuous in this way is to say they are numerically identical

• This is true even if they are not (absolutely) qualitatively identical.

• Consider: • You are numerically identical with who you were a year ago.

• But you are not entirely qualitatively identical with who you were a year ago.

• What is true is that the qualitative changes happen in small doses and over time.

• E.g. • ABCDEFG

• BBCDEFG

• BBCDAFG

• BBDDAFG

• BBDDAAG

Review: Computational Continuity/Equivalence

• To be computationally equivalent, two systems must have the same sub-systems and/or representations

• To be computationally continuous, system 1 at time T must have most of the same systems and/or representations as system 2 at time T1. • Alternatively, if there are big changes, they must be gradual.

Key Concepts

• Sim World = a world that is entirely run on a computer(s) and populated by sims • Sim = a being in the sim world

• Virtual Reality = a world that is entirely run on computers but inhabited by people in the physical world

• Nested World = A world inside another world

• Base World = World containing another world • Can be relative (World 1 is the base world of World 2) • Or absolute (This world is the base world = not nested in any other worlds)

• Phenomenal Aspect of World = The sum total of sensible objects properties of a world (think phenomenology = experience, phenomenon = object of experience)

• Substrate of World = The most basic level of a world, what underlies the phenomenal aspect • Sim worlds/Virtual realities have code as their substrates • Substrate of a Mind = that which a mind is realized on

• Intuitively, our minds are realized in brains • But the mind of a Sim can be realized in the same code as the substrate of a sim world • It can nonetheless be computationally equivalent to (as complex as) our minds!

Reality

• What do we mean by ‘reality’? • In one sense, the real world is whatever world we inhabit. • But we generally think it means more than that.

• Our intuitive picture of reality • Reality is mind-independent • The substrate of reality is matter and energy • Reality is the (absolute) base world

• Skeptical scenarios challenge these assumptions • When we are presented with a challenge to any of the premises of the ‘intuitive

picture’ we have a choice: • Concede that the world we are in is not the real world • Or re-define reality • Chalmers will discuss this question.

Bostrom’s Argument

• It is possible we are Sims and don’t know it. • We have access to the phenomenal aspect of our world and ourselves, but not the

substrate. • If computing is sufficiently complex, sim worlds could be as complicated as ours.

• If we were in one, we wouldn’t know the difference. • If CTM is true and computing is sufficiently complex, sim minds could be as complex as ours.

• If we were such sims, we wouldn’t know the difference.

• Not only possible, but likely. • Once a society can build one sim/sim world as complex as ours, the rest are cheap. • Thus, there is reason to think there are many more sims/sim worlds than organic

beings/physical worlds. • Unless there is some reason to think otherwise. • Possible reasons include:

• Societies regularly destroy themselves before developing tech • Societies just don’t care.

• Bostrom rejects both.

David Chalmers

• Australian Philosopher

• Professor of Philosophy, New York University (#1 Philosophy Department in World).

• Interested in Metaphysics and Philosophy of Mind

• Arguably most famous living philosopher of mind

• Aside from what we are reading he is famous for: • Study of Consciousness • Extended Mind Hypothesis

The Matrix: Skeptical vs. Metaphysical Interpretations

• Suppose you are in the Matrix (or, better, a world like the Matrix but not an imperfect Simulation).

• Suppose you believe you are in Tucson, and your senses support this belief.

• Chalmers asks: Is your belief that you are in Tucson true? Are you in Tucson?

• Skeptical reading: No, it is false. You are in a vat somewhere, so unless that vat happens to be in Tucson, you are not. • Even if the vat is in Tucson, your true belief is accidental, therefore not knowledge.

• Metaphysical reading: Yes, it is true. What it is to be in Tucson is to be in a certain ‘position’ in the Sim world.

• Note the relationship: • Skeptical reading → Reality is what I think it is, but I am not in the real world. • Metaphysical reading → Reality is not what I thought it was, but I am in the real world.

The Metaphysical Hypothesis

• The Combination Hypothesis consists in three separate hypotheses all being true. The Metaphysical Hypothesis is a version of the Combination Hypothesis.

• First Hypothesis = Creation Hypothesis. • Creation Hypothesis: “Physical space-time and its contents were created by beings

outside physical space-time” (Chalmers, 39). • One version of the Creation Hypothesis is the belief that a God (or gods) outside the physical

universe created the physical universe. Most people probably believe something like this.

• Another version of the Creation Hypothesis is that “our world was created by a relatively ordinary being in the ‘next universe up’” (Chalmers, 39).

• Another way of putting this: our world is not the base level, and something in the base level (or at least a level closer to the base level than ours) created our world.

• It is not (yet) saying we are in a Sim world. For that requires…

The Metaphysical Hypothesis

• The Combination Hypothesis consists in three separate hypotheses all being true. The Metaphysical Hypothesis is a version of the Combination Hypothesis.

• Second Hypothesis = The Computational Hypothesis • Computational Hypothesis: “Metaphysical processes throughout space-time are constituted by underlying

computational processes” (Chalmers, 40). • Does not deny that there are physical particles. Just adds that there is something underlying even the smallest physical

particles, and says that this thing is computational.

• Restated more formally: our substrate is made up of computational processes. • Physical objects exist, but are not at substrate level. • Further, facts about substrate do not change the truth of our beliefs about the phenomenal world.

• Whether I am in Tucson = fact about world at my level, not fact about world at some other level. • If Computational Hypothesis is true for my (level) world, then whether I am in Tucson = fact about computational processes or

‘code’ underlying my world. • Different from appearance = reality: I can be mistaken about being in Tucson, even if the Computational Hypothesis is true.

• Suppose I thought I got on a plane to Tucson, but I really got on a plane to Phoenix. Then my belief that I am in Tucson would be false.

• What would not make my belief false is if I am an envatted being at some base (or more basic) level in Phoenix at that level, but am in Tucson in my world.

• The Computational Hypothesis added to the Creation Hypothesis gets you a Sim World. But not yet the Matrix, which needs…

The Metaphysical Hypothesis

• The Combination Hypothesis consists in three separate hypotheses all being true. The Metaphysical Hypothesis is a version of the Combination Hypothesis.

• Third Hypothesis = The Mind-Body Hypothesis • Mind-Body Hypothesis: “My mind is (and has always been) constituted by processes outside physical space-

time, and receives its perceptual inputs from and sends its outputs to processes in physical space-time” (Chalmers, 41).

• Refers to realization basis/substrate of minds. • If computational and mind-body hypotheses are true then substrate of world = code, substrate of mind = (potentially) matter

• Helpful to think of ‘physical space-time’ as relative to a world.

• Key difference between envatted beings and Sims: • If you are a Sim, then only Computational Hypothesis must be true.

• Your mind is not outside of ‘physical space-time’ relative to that world.

• If you are an envatted being, then both Computational and Mind-Body hypotheses must be true. • Your mind is outside ‘physical space-time’ relative to that world. • Not to be confused with Computational Theory of Mind. If the Computational Hypothesis is true, then the world is made up of

computational processes (code). But, if you are an envatted being, then your mind is made up of a different kind of computational process.

• Counterintuitive claim: even if the world you are in is computational, and the world more basic than yours is physical at the lowest level (i.e. has a substrate of matter rather than computations), if you are an envatted being, then your mind is outside ‘physical space-time.’

Let’s Visualize All This

Sim World Base World

01010111111000000001111100 101011010

Sim Chalmers

Envatted Chalmers

Brain of Envatted Chalmers

Nouminal World of Sim Level

‘Physical’ objects in Sim World

Note: ‘Physical space-time’ refers to what is inside the Sim world, even if it is based in code and the base world is not.

The Metaphysical Hypothesis

• Call the combination of Creation, Computational, and Mind-Body hypotheses the Combination Hypothesis.

• The Metaphysical Hypothesis is the Combination Hypothesis plus the claim that “the computational processes underlying physical space-time were designed by the creators as a computer simulation of a world” (Chalmers, 42). • In other words, the standard (theistic) interpretation of the Creation hypothesis is

ruled out.

• Metaphysical Hypothesis = Matrix Hypothesis • If Metaphysical Hypothesis is true, then “I have (and have always had) an

isolated cognitive system that receives its inputs from and sends its outputs to an artificially designed computer simulation of a world. This is just the Matrix Hypothesis” (Chalmers, 43).