From owner-cse575-fa08-list@LISTSERV.BUFFALO.EDU Tue Sep 2 20:17:03 2008 Received: from ares.cse.buffalo.edu (ares.cse.buffalo.edu [128.205.32.79]) by castor.cse.Buffalo.EDU (8.13.6/8.12.10) with ESMTP id m830H3bb021168 for ; Tue, 2 Sep 2008 20:17:03 -0400 (EDT) Received: from postscanC.acsu.buffalo.edu (postscanc.acsu.buffalo.edu [128.205.5.203]) by ares.cse.buffalo.edu (8.13.8/8.13.6) with ESMTP id m830H099014994 for ; Tue, 2 Sep 2008 20:17:00 -0400 (EDT) Received: from listserv.buffalo.edu (listserv.buffalo.edu [128.205.4.140]) by postscanC.acsu.buffalo.edu (Postfix) with ESMTP id 7DAFD2025B; Tue, 2 Sep 2008 20:16:40 -0400 (EDT) Received: by LISTSERV.BUFFALO.EDU (LISTSERV-TCP/IP release 15.5) with spool id 17428767 for CSE575-FA08-LIST@LISTSERV.BUFFALO.EDU; Tue, 2 Sep 2008 20:16:37 -0400 Delivered-To: cse575-fa08-list@listserv.buffalo.edu Received: (qmail 15148 invoked from network); 3 Sep 2008 00:16:20 -0000 Received: from unknown (HELO mxB.acsu.buffalo.edu) (128.205.5.197) by listserv.buffalo.edu with SMTP; 3 Sep 2008 00:16:20 -0000 Received: from mxB.acsu.buffalo.edu (localhost [127.0.0.1]) by localhost (Postfix) with SMTP id 8ADA57A9 for ; Tue, 2 Sep 2008 20:16:20 -0400 (EDT) Received: from mxB.acsu.buffalo.edu (localhost [127.0.0.1]) by mxB.acsu.buffalo.edu (Postfix) with ESMTP id 8DFD25732 for ; Tue, 2 Sep 2008 20:16:17 -0400 (EDT) Received: from castor.cse.Buffalo.EDU (castor.cse.Buffalo.EDU [128.205.32.14]) by mxB.acsu.buffalo.edu (Prefixe) with ESMTP id 8685B572E for ; Tue, 2 Sep 2008 20:16:17 -0400 (EDT) Received: from castor.cse.Buffalo.EDU (rapaport@localhost [127.0.0.1]) by castor.cse.Buffalo.EDU (8.13.6/8.12.10) with ESMTP id m830GHpk021105 for ; Tue, 2 Sep 2008 20:16:17 -0400 (EDT) Received: (from rapaport@localhost) by castor.cse.Buffalo.EDU (8.13.6/8.12.9/Submit) id m830GHxu021104 for cse575-fa08-list@listserv.buffalo.edu; Tue, 2 Sep 2008 20:16:17 -0400 (EDT) X-PM-EL-Spam-Prob: : 7% Message-ID: <200809030016.m830GHxu021104@castor.cse.Buffalo.EDU> Date: Tue, 2 Sep 2008 20:16:17 -0400 Reply-To: "William J. Rapaport" Sender: Introduction to Cognitive Science From: "William J. Rapaport" Subject: 575: Further comments on philosophy (long message!) To: CSE575-FA08-LIST@LISTSERV.BUFFALO.EDU Precedence: list List-Help: , List-Unsubscribe: List-Subscribe: List-Owner: List-Archive: X-DCC-Buffalo.EDU-Metrics: castor.cse.Buffalo.EDU 1336; Body=0 Fuz1=0 Fuz2=0 X-Spam-Status: No, score=-1.2 required=5.0 tests=AWL autolearn=disabled version=3.1.8 X-Spam-Checker-Version: SpamAssassin 3.1.8 (2007-02-13) on ares.cse.buffalo.edu X-Virus-Scanned: ClamAV 0.91.2/8142/Tue Sep 2 17:27:04 2008 on ares.cse.buffalo.edu X-Virus-Status: Clean Status: R Content-Length: 12341 ------------------------------------------------------------------------ Subject: Further comments on philosophy ------------------------------------------------------------------------ Here are some miscellaneous notes on philosophy. 1. ------------------------------------------------------------------------ Gardner makes an interesting observation that philosophy formulates research questions (i.e., makes research proposals), other disciplines seek the answers, and philosophy then critiques the results. That's not too unfair, but often philosophy contributes to seeking the answers as much as any of the other disciplines. 2. ------------------------------------------------------------------------ Philosophy tends to splinter, in that many now-independent academic disciplines were once part of philosophy: physics, psychology, sociology, perhaps logic. I.e., philosophy's successes are no longer considered to be part of philosophy. AI suffers from this to some extent: "B. Raphael...has suggested that AI is a collective name for problems which we do not yet know how to solve properly by computer" (Michie, Donald, "Formation and Execution of Plans by Machine," in N.V. Findler & B. Meltzer (eds.) (1971), Artificial Intelligence and Heuristic Programming (New York: American Elsevier): 101-124; quotation on p. 101). Note that it follows that once we do know how to solve them, they are no longer AI! Thus, philosophy (as well as AI) *appears* to make no progress. But it does: * There are technical results in logic, philosophy of language, etc. (just read any professional journal in these fields). This is because, as I noted above, philosophy contributes to seeking the answers to its own questions. * Philosophy makes progress by helping to clarify and sharpen ideas. For a discussion of this, see "Can there be progress in philosophy? Can philosophy ever solve any of its problems?", online at: http://www.cse.buffalo.edu/~rapaport/584/S07/whatisphil.html#progress 3. ------------------------------------------------------------------------ Last (and longest), here's a selective history of philosophy relevant to cognitive science: A. ------------------------------------------------------------------------ METAPHYSICS is the branch of philosophy that investigates theories about what exists, what kinds of things there are, what their properties and relationships are, etc. EPISTEMOLOGY is the branch of philosophy that investigates theories about how we can have knowledge. B. ------------------------------------------------------------------------ Two major epistemological theories are "rationalism" and "empiricism". RATIONALISM says that the source of knowledge is: reason. It takes logic and math as paradigm disciplines. This is supposed to guarantee that our knowledge is absolutely certain. EMPIRICISM says that the source of knowledge is: experience, structured by reasoning. It takes science as the paradigm. But note that we can err when making observations, thus our knowledge cannot be certain! Two principal rationalists were Descartes and Leibniz. DESCARTES (1596-1650) is famous for inventing analytic geometry and for his "cogito ergo sum" ("I think; therefore, I am"), which we discussed in lecture. LEIBNIZ (1646-1716) is famous for inventing world's fairs and the calculus, and for the idea of a "characteristica universalis"--a universal language or alphabet or algebra of thought that would allow disputes to be settled by pure reasoning ("come, let us reason together"). Some current philosophers consider it to be the forerunner of symbolic AI. A central notion for the rationalists was that of "INNATE IDEAS": ideas that we are born with. Leibniz offered the metaphor that the mind at birth was like a slab of marble with veins in it: The veins constrained ideas to take certain "shapes". Later cognitive scientists (e.g., Chomsky) argued that certain features of human cognition had to be innate (e.g., our ability to learn language). The 3 principal empiricists, all "British" (though one was English, one Irish, and one Scottish, respectively), were Locke, Berkeley, and Hume. LOCKE (1632-1704, thus overlapping Descartes and a near-contemporary of Leibniz) disagreed about innate ideas, offering the metaphor of the mind at birth as a "tabular rasa" (a blank slate), upon which experience writes. He distinguished between two kinds of properties: primary, which are physical properties (like shape and extension) that belong to objects, and secondary, which are properties produced by--but not located "in"--objects when they come into contact with a mind (like color, and other sensory properties). BERKELEY (1685-1753), an idealist (as we discussed in lecture), claimed that *all* properties were secondary. And HUME (1711-1776; note that he died the year of American independence) held that the mind was (merely) a sequence of ideas. He is also known for his theory that causation cannot be found in nature, but only "constant conjunction", i.e., correlations. C. ------------------------------------------------------------------------ These two schools of thought were more or less reconciled by KANT (1724-1804), the great German philosopher (some say, the greatest philosopher since Aristotle). [By the way, just for chronological comparison, Beethoven lived from 1770-1827.] Kant agreed with Hume that there were no necessary causal connections in nature, but that we humans impose such connections onto nature (this solves Hume's problem). He also believed that you can't answer metaphysical questions without first answering epistemological ones; after all, how would you know if your metaphysical theories are correct if you don't first have a theory about how to identify correct theories? So, for Kant, the fundamental philosophical question was: How is it possible for us to have knowledge? In particular, how is it possible to have what he called "synthetic a priori" knowledge? What's that? Consider the following table: | a priori judgments | a posteriori judgments | --------------------------------------------------------- synthetic | A | B | judgments | | | --------------------------------------------------------- analytic | C | D | judgments | | | --------------------------------------------------------- "synthetic" judgments are those in which the predicate (verb phrase) is not part of the subject (noun phrase); I'll give examples below. "analytic" judgments are those in which the predicate *is* contained in the subject. "a priori" (that's Latin for "prior to (i.e., independent of) experience") judgments are rational, chronologically and logically prior to observation and experience, and universal and necessary links between subject and predicate. "a posteriori" (Latin for "posterior to (i.e., following after, or dependent upon) experience") judgments come after, and are based on, experience. So, we have 4 logically possible kinds of judgments: A: synthetic a priori B: synthetic a posteriori C: analytic a priori & D: analytic a posteriori Here are some examples: A: 7+5=12 statements of physics statements of metaphysics B: grass is green this rose is red C: bald people lack hair red roses are red red roses are roses D: [the set of analytic a posteriori sentences is empty; they're not possible, according to Kant] Again, his question was how type-A judgments are possible; they don't seem to require experience, but they are not merely logically true. Kant's answer: The mind brings *ordering principles* to the "blooming, buzzing confusion" of sensory experience (that phrase is due to William James, not Kant). These ordering principles are what Kant called "forms of intuition"; they are space and time. So, we put on our "space/time eyeglasses" and suddenly are able to see the world clearly. Among these principles are what Kant called "categories of thought": quality (affirmative, negative...) quantity (universal, particular...) relation (categorial, hypothetical...) manner (modality: possible, necessary, exists) And we have "schemes" for interpreting raw sensory data. Thus: "Thoughts without content are empty; intuitions without concepts are blind." So much for Kant's epistemology. What about his metaphysics? There is (1) a world of things-as-they-are-"in themselves", independent of how we think of them. But, because we can only think of them in terms of our space/time glasses and categories of thought, we cannot say what they are like "in themselves": Our concepts don't apply to them, so they are unknowable. He called them "noumena" (singular: noumenon). And there is (2) the world as it is constructed by us, which is knowable, but only in terms of *our* concepts. This is the world of "phenomena" (singular: phenomenon). Note how word usage has changed: Modern science studies "phenomena", which is usually taken to mean something like "things out there in the world". But that's NOT what Kant said that "phenomena" are! D. ------------------------------------------------------------------------ After Kant, came the German Idealists, like Hegel. They believed in crazy things like "the Absolute" and made deep, and deeply puzzling, statements like: Das Nichts nichts (The Nothing nothings). We now quickly move on to (oh, I should mention that some folks in AI and cognitive science think that the Hegelians and their intellectual descendents were on the right track!)... E. ------------------------------------------------------------------------ Logical Empiricism and Logical Positivism: These were philosophical movements based on successes in reducing math to logic + set theory (e.g., as accomplished by Whitehead and Russell, in their 3-volume Principia Mathematica). The logical empiricists and positivists put an emphasis on "analysis": the analysis of language, of concepts, etc., as opposed to the kind of system-building ("synthesis") conducted by the German Idealists. They took sensory data as primitive (especially Russell; see, e.g., his "Logical Atomism") and structured it according to logic, in order to "rationally reconstruct" the world (a task taken on by Carnap, in his _Logical Structure of the World_). They tried to eliminate "speculative" metaphysics. Their weapon of choice was the Verification Theory of Meaning: The meaning of a proposition P is the method of verifying it (see A.J. Ayer, _Language, Truth, and Logic_). In the 1950s, Alonzo Church (one of the founders of computer science) logically proved that this theory, when spelled out in detail, would not work. F. ------------------------------------------------------------------------ Next in our whirlwind tour is W.V. Quine, one of the greatest philosophers of the last century, certainly the most important of the last half of the 20th century. In his article "2 Dogmas of Empiricism", he dealt the final death blow to logical positivism, argued against the analytic/synthetic distinction, and argued *for* a holistic "web of belief": that all statements of science, math, logic, and philosophy, and everything else, form a vast, interconnected web, and a change to any part of it would affect all of it. G. ------------------------------------------------------------------------ At some point during this history, there was a "linguistic turn". Wittgenstein (Russell's student, and another of the greatest 20th-century philosophers) focussed on what some call "ordinary language philosophy", saying that meaning was "use": What an expression means depends on how it is used. Austin and Searle developed "speech-act theory": sometimes we perform actions by saying words, as when a duly authorized person says "I now pronounce you husband and wife"--that person is not just calling them married but *making* them married. And Quine, in _Word and Object_ set as his goal to understand the "meaning" of psychological terms such as "believe" in an "austere" language that refers only to physical objects (as well as numbers and sets). There's a lot more I could say, but this is already long enough :-)