Presentation on theme: "Constructing the World Week 4 David Chalmers. The Case for Scrutability (1) PQTI and the Cosmoscope (2) The Cosmoscope Argument (3) Empirical Scrutability."— Presentation transcript:
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 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: PQTI. Includes P: microphysical and macrophysical truths, in (final plus classical) physical vocabulary Q: phenomenal truths, in pure phenomenal vocabulary T: a thats-all truth I: indexical truths: I am..., Now is.... Laws and counterfactuals in the vocabulary of P and Q.
Positive Truths To avoid issues about characterizing T (in terms of apriority), Ill 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 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 Cosmoscope in empirical mode: Tells one about the character of ones own world. Relevant to Empirical Scrutability Cosmoscope in conditional mode: Tells one about a scenario that may or may not be ones own world, to enable conditional conclusions. Relevant to Conditional and A Priori Scrutability
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 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 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 (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. (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 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 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 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 ones environment. It also enables one to rule out arbitrary skeptical hypotheses. Knowing this enables one to know all ordinary truths.
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 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 isnt scrutability from original PQI. Problem 2: paradoxes of will/action.
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 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 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 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 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 Conceptual objection: The idealization isnt well-defined. Infinitary reasoners are presumably possible, and there are facts about what they could know. Epistemological objection: We cant know what these reasoners could know. Why not? We can reason generally as before. Perhaps theyll correct our views about whats true, but the arguments will still go through. Objection from applicability: Next time.