Philosophical sources

2.1 Yudkowsky and the Sequences

Eliezer Yudkowsky's essays distinguish epistemic rationality, concerned with accurate beliefs, from instrumental rationality, concerned with acting effectively toward one's ends. For Yuddish this yields a basic grammatical separation: a truth assessment belongs to epistemic grammar, while a goal or directive belongs to a different utterance type. A preferred outcome does not acquire a higher probability merely because it is preferred. This is a language-design interpretation of the distinction in “What Do I Mean By Rationality?”.

The Sequences are a body of essays organized into collections. “Feeling Rational” is the second opening essay in the 2015 book edition used here; it is not itself the whole second sequence. Its treatment of emotion makes it a useful test of whether Yuddish can describe feelings without treating rationality as emotional numbness. See “Feeling Rational”.

2.2 Bayesianism

Bayesian reasoning represents uncertainty using probabilities and revises those probabilities by conditioning on evidence. For a hypothesis H, evidence E, and background information K:

P(H given E,K) = P(E given H,K) × P(H given K) / P(E given K).

The language uses base-2 log-odds because the corresponding update is additive. It also distinguishes a posterior probability from a likelihood: confidence in H after seeing E is different from how likely E would have been if H were true. Yuddish does not settle disputes about how to choose priors, build models, or obtain likelihoods. It provides ways to say what one used.

Bayesianism is broader than the writings of any one author or community. The elementary identities in this document are mathematical constraints; the choice to grammaticalize them, and the proposed vocabulary for doing so, belong to the conlang.

2.3 LessWrong

LessWrong describes itself as a forum and community concerned with improving reasoning and decision-making, with a substantial interest in Bayesian reasoning and artificial intelligence. Its community contains disagreements and changing practices; it is not a single doctrine or a synonym for Yudkowsky. Yuddish draws on recognizable discussion habits associated with that setting: explicit credences, distinguishing observations from interpretations, revising beliefs, and asking what a claim predicts. See LessWrong's introduction.

The name LessWrong is retained as a proper name. A playful descriptive calque is veniker-falsh / װײניקער־פֿאַלש, “less wrong,” but that expression need not replace the community's name.

2.4 Maps, predictions, and definitions

A belief or model describes something; it is not the thing described. Yuddish makes model construction an explicit act and gives displayed wording a quotation operator. This helps distinguish an event, a representation of the event, and a sentence used to name that representation.

The idea that beliefs should constrain expectations motivates a request for a discriminating prediction: what observable outcome would differ if the hypothesis were false? This is a practical reading of “Making Beliefs Pay Rent”. It does not require every useful concept to denote something directly visible.

Definitions need their own operator because choosing a label does not establish an empirical fact. A request to restate a disputed word in operational terms is inspired by “Taboo Your Words”. In Yuddish, defining intelligence never by itself establishes that a particular system has it.

2.5 Fallibility and the probability endpoints

Yudkowsky's “0 and 1 Are Not Probabilities” motivates the language's refusal to express empirical certainty as an infinite epistemic strength. A prior of zero cannot be rescued by ordinary conditioning on evidence of positive marginal probability; a prior of one has the corresponding problem for its complement.

The mathematical distinction matters: 0 and 1 are valid probabilities in standard probability theory. They occur in formal models and probability measures. Yuddish's restriction is a rule for fallible empirical assertion. It does not outlaw deterministic models, logical identities, or zero-measure events. Those can be discussed inside explicit mathematical or model frames.

Every finite empirical bit value remains revisable. A speaker may say avavav, but the repeated syllables still denote a finite number. Proof claims likewise distinguish what follows in a formal system from the fallible claim that a human checked the proof correctly.