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Constructing the World Week 4. David Chalmers. The Case for Scrutability. (1) PQTI and the Cosmoscope (2) The Cosmoscope Argument (3) Empirical Scrutability (4) Conditional Scrutability. Scrutability of Ordinary Truths.

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Constructing the world week 4
Constructing the WorldWeek 4

  • David Chalmers


The case for scrutability
The Case for Scrutability

  • (1) PQTI and the Cosmoscope

  • (2)The Cosmoscope Argument

  • (3) Empirical Scrutability

  • (4) Conditional Scrutability


Scrutability of ordinary truths
Scrutability of Ordinary Truths

  • Aim: make an initial case that there is a compact class of truths such that all ordinary truths are scrutable from base truths.

  • Ordinary truths: macroscopic truths such as ‘Water is H2O’, ‘Life on our planet is based on DNA’, ‘Platypuses are mammals’, etc.

  • Hard cases (math, mental, moral, modal, social, metaphysical, vague, names, deference, ...) later.

  • Issues specifically about a priori scrutability next week.


Base truths
Base Truths

  • Base Truths: PQTI. Includes

    • P: microphysical and macrophysical truths, in (final plus classical) physical vocabulary

    • Q: phenomenal truths, in pure phenomenal vocabulary

    • T: a “that’s-all” truth

    • I: indexical truths: ‘I am ...’, ‘Now is ...’.

    • Laws and counterfactuals in the vocabulary of P and Q.


Positive truths
Positive Truths

  • To avoid issues about characterizing T (in terms of apriority), I’ll argue for: all ordinary positive truths are scrutable from PQI.

  • Positive truths: Those that cannot conceivably be falsified by adding something to a world.

    • E.g. ‘There are more than five particles’

    • Not: ‘There is no ectoplasm’, ‘Everything alive is made of DNA’.


The cosmoscope
The Cosmoscope

  • A virtual reality device that stores the information in PQI and makes it usable. It contains

    • (i) a supercomputer to store and calculate

    • (ii) holographic tools that use P to zoom and display information about matter in regions

    • (iii) virtual reality for knowledge of experience

    • (iv) a “you are here” marker

    • (v) a simulation mechanism for knowledge of counterfactuals


Empirical and conditional mode
Empirical and Conditional Mode

  • Cosmoscope in empirical mode: Tells one about the character of one’s own world.

    • Relevant to Empirical Scrutability

  • Cosmoscope in conditional mode: Tells one about a scenario that may or may not be one’s own world, to enable conditional conclusions.

    • Relevant to Conditional and A Priori Scrutability


Using a cosmoscope
Using a Cosmoscope

  • Say a subject utters S. They could then in principle use a Cosmoscope to investigate the truth of S.

    • In empirical mode, determine the truth of S.

    • In conditional mode: determine whether, if things are as the Cosmoscope describes, S is true.


The joys of the cosmoscope
The Joys of the Cosmoscope

  • The Cosmoscope delivers multiple supermovies of the world:

    • phenomenological supermovies, geometrical supermovies, counterfactual supermovies, microphysical supermovies

    • at all locations and scales of space and time

  • One could clearly use this to come to know very many ordinary truths.


The cosmoscope argument
The Cosmoscope Argument

  • 1. All ordinary truths are scrutable from a Cosmoscope.

  • 2. If a truth is scrutable from a Cosmoscope, it is scrutable from PQI.

  • _________________________

  • 3. All ordinary truths are scrutable from PQI.


Case for premise 1
Case for Premise 1

  • (1) All knowable ordinary truths are knowable through perception, introspection, and reasoning

  • (2) Any truth knowable through perception, introspection, and reasonable is scrutable from a Cosmoscope

  • ______________________

  • (3) So: all knowable ordinary truths are scrutable from a Cosmoscope.


The case for premise 1 continued
The Case for Premise 1, continued.

  • (3) All knowable ordinary truths are scrutable from a Cosmoscope.

  • (4) All unknowable ordinary truths are Fitch-unknowable or scale-unknowable.

  • (5) Scale-unknowability is no obstacle to scrutability and Fitch-unknowability is an obstacle only to empirical scrutability; so

  • (6) All ordinary truths are conditionally scrutable and all non-Fitchian truths are empirically scrutable from a Cosmoscope.


The case for premise 2
The Case for Premise 2

  • The Cosmoscope is simply providing information in PQI along with truths for reasoning with this information.

  • Anything that can be known with the aid of a Cosmoscope can be known by an ideal reasoner given PQI, without the aid of a Cosmoscope.

  • So: Any truth scrutable from a Cosmoscope is scrutable from PQI.


Another case for scrutability
Another Case for Scrutability

  • One can make a more detailed case for Scrutability by considering how one can reason from PQI.

  • Use Q to know phenomenal truths and as a prima facie guide to perceptual truths.

  • Use counterfactuals about Q as a guide to more

  • Use P to rule out skeptical perceptual scenarios, and as a guide to unperceived parts of the world.

  • Use Q as a guide to other minds.

  • And so on.


The completeness of pqti
The completeness of PQTI

  • P enables knowledge of geometrical structure and dynamics at all levels. Q enables knowledge of experience and appearance.

  • Together, PQTI enables knowledge of (actual and counterfactual) appearance, behavior, composition, distribution of all bodies of matter in one’s environment.

  • It also enables one to rule out arbitrary skeptical hypotheses.

  • Knowing this enables one to know all ordinary truths.


Empirical scrutability
Empirical Scrutability

  • Not all truths are empirically scrutable from a Cosmoscope.

    • E.g. ‘There is no Cosmoscope’

    • P, Q

  • One could just exclude non-Fitchian truths.


Complete cosmoscopes
Complete Cosmoscopes

  • Best to suppose that the Cosmoscope is a nonphysical device that only affects a local piece of spacetime, then erases all traces.

  • Complete Cosmoscope: Delivers PQI*, true in world of use (not original world)

    • Problem 1: scrutability from Cosmoscope isn’t scrutability from original PQI.

    • Problem 2: paradoxes of will/action.


The incomplete cosmoscope
The Incomplete Cosmoscope

  • Incomplete Cosmoscope: Delivers PQI-, truths common to original world and world of use.

    • “Local” truths about the area of Cosmoscope interaction are excluded.

  • Empirical Scrutability: All nonlocal truths are scrutable from PQI-.

    • This avoids Fitchian worries?


Conditional scrutability
Conditional Scrutability

  • For all ordinary true sentence tokens M, the speaker is in a position to know that if PQI’, then M (PQI’ = conjunction of PQI).

  • This requires cr*(M|PQI’) to be high.


Argument for conditional scrutability
Argument for Conditional Scrutability

  • Direct: All ordinary truths are conditionally scrutable from a Cosmoscope, so from PQI.

  • Indirect: (i) Empirical scrutability says knowledge of PQI- suffices for knowledge of nonlocal M. (ii) Conditionalization suggests: before knowing PQI-, one is in a position to know that if PQI-, then M. (iii) Locality/Fitch pose no special worries for Conditional Scrutability. So (iv) Conditional Scrutability.


The objection from experience
The Objection from Experience

  • Having a perceptual experience provides grounds for knowledge in a way that merely knowing about the experience does not.

  • But: perception plays its epistemic role in virtue of providing knowledge of certain perceived states of affairs: shapes, colors, etc. That knowledge is also provided by PQI.

  • What about high-level contents? The argument for scrutability goes through even assuming low-level contents, so high-level contents are epistemologically inessential.


The objection from idealization
The Objection from Idealization

  • Arguments for Scrutability require a strong idealization of reasoning, memory, etc.

    • Infinite capacity, infinitary reasoning!

  • The Cosmoscope offloads some but not all of the idealization.


Three objections from idealization
Three Objections from Idealization

  • Conceptual objection: The idealization isn’t well-defined.

    • Infinitary reasoners are presumably possible, and there are facts about what they could know.

  • Epistemological objection: We can’t know what these reasoners could know.

    • Why not? We can reason generally as before. Perhaps they’ll correct our views about what’s true, but the arguments will still go through.

  • Objection from applicability: Next time.


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