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Constructing the World Week 4

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

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  1. Constructing the WorldWeek 4 • David Chalmers

  2. The Case for Scrutability • (1) PQTI and the Cosmoscope • (2)The Cosmoscope Argument • (3) Empirical Scrutability • (4) Conditional Scrutability

  3. 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.

  4. 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.

  5. 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’.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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?

  19. 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.

  20. 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.

  21. 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.

  22. 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.

  23. 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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