Path: utzoo!attcan!uunet!decwrl!shelby!neon!Neon!jmc From: jmc@Gang-of-Four.usenet (John McCarthy) Newsgroups: comp.ai.philosophy Subject: Re: Reasoning Paradigms Message-ID: Date: 8 Oct 90 12:32:35 GMT References: <9963@ccncsu.ColoState.EDU> Sender: news@Neon.Stanford.EDU (USENET News System) Followup-To: comp.ai.philosophy Organization: /u/jmc/.organization Lines: 29 In-Reply-To: petersja@debussy.cs.colostate.edu's message of 5 Oct 90 20:51:27 GMT Peters writes "This is Smolensky's chicken and egg problem: Does "hard," logical, rule-based reasoning ground all reasoning, or does "soft," evaluative, inductive, rough, pattern recognizing, fuzzy, kinds of reasoning ground all our thought processes, including "hard" scientific thinking? Or are they independent? Smolensky suggests that soft reasoning grounds the hard, while Minsky (and Fodor) appear to believe that hard thinking grounds any soft thinking." Minsky will doubtless tell you that logic isn't what he is enthusiastic about, whereas I am an enthusiast for logic. However, I wouldn't claim that logic "grounds" all reasoning, because I think grounding is an oversimplified notion. The human ability to do logic developed from and still uses processes that can be called reasoning but don't correspond to logic. These processes are inaccurate in unnecessary and inconvenient ways. These inaccurate human processes did form a desire to develop accurate reasoning processes, i.e. logic. As a branch of mathematics, logic is grounded in formal semantics as Tarski and others have described, i.e. it has been made independent of the thought processes that motivated its development. For full AI, mathematical logic needs supplements such as formalized nonmonotonic reasoning and probably formalized contexts, but these aren't reversions to ordinary soft thinking. We can make an analogy with the fact that we can write an interpreter for any good programming language in any another. We can talk about logic in ordinary language, and we can formalize ordinary language and reasoning in logic.