Link to original article

Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: ELK Thought Dump, published by Abram Demski on February 28, 2022 on The AI Alignment Forum. I recently spent a couple of weeks working on ELK. What follows is a somewhat disorganized thought-dump, with the post-hoc theme of relating ELK to some common ideas in philosophy. I'll assume familiarity with the ELK document. You can read quick summaries on some other reaction posts, so I won't try to recap here. Everything here should be read as "threads for further research" -- many of these sections could be long posts in themselves if I tried to fully formalize them, or even to unpack all my thoughts so far. I've numbered sections which contain semi-concrete ELK proposals. As a result, the section numbers will be weird -- for example, "2. Truth Tracking" is not the second section. Semantics The problem at the heart of ELK is that of semantics, that is, ascribing meaning. The leading theory (for LessWrongers, at least) is the map/territory analogy, according to which beliefs are like a map, and the world is like a territory. A map has a "scale" and a "key" which together tell us how to relate the map and the territory. Likewise, beliefs are thought to have a "correspondence" which tells us how to relate belief to reality. In academic philosophy, this is known as the correspondence theory of truth (rather than "the map territory theory of truth"). LessWrong is pretty big on the map/territory distinction, but (I think) has historically been far more interested in applying the idea than developing or analyzing it. While map/territory semantics seems pretty obvious, it gets weird when you start looking at the details. This has caused some philosophers to abandon it, and develop alternatives (some of which are quite interesting to me). Alex Flint has an extensive discussion of problems with some possible theories of truth. This post is my take on the issue. Semantics vs Truth Sometimes, the correspondence theory of truth is rendered via Tarski's T-schema: True("The moon is made of blue cheese.") ↔ The moon is made of blue cheese. There are other replies that can be given, but my reply is as follows. I am interested in "truth" only as a way of getting at meaning/semantics. A definition of truth should shed light on what it means for something to be true; why it is considered true. It should help me cope with cases which would otherwise be unclear. In other words, the T-schema tells us nothing about the nature of the correspondence; it only says that the predicate "true" names the correspondence. When I say something is true, I am (according to the correspondence theory) asserting that there is a correspondence; but Tarski's T-schema offers me no help in unpacking the nature of this correspondence further. The T-schema is very important in the subfield of logic dealing with formal theories of truth. The idea of this subfield is to construct axiomatic logics of truth, which avoid paradoxes of truth (most centrally, the Liar paradox). This is a fascinating field which is no doubt relevant to semantics. However, like the T-schema, these theories don't clarify the connection between truth and the external world. They focus primarily on self-consistency, and in doing so, only clarify dealings with mathematical or logical truth, with little/nothing to say about empirical truth. I will spell out the following hypothesis connecting meaning to truth: Truth-functional semantics: The meaning of an assertion is fully captured by its truth-conditions. Under what condition is the assertion true, false, and (if relevant) any other truth-values (such as "nonsensical", if this is regarded as a truth-value). This is the "truth function" of the assertion; the idea that semantics boils down to truth-functions is an old one in logic. (According to correspondence theory, the truth-function will speci...