Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!mailrus!tut.cis.ohio-state.edu!bloom-beacon!XEROX.COM!hayes.pa From: hayes.pa@XEROX.COM Newsgroups: comp.ai.digest Subject: Re: Consensus and Reality Message-ID: <19880610203400.5.NICK@INTERLAKEN.LCS.MIT.EDU> Date: 10 Jun 88 20:34:00 GMT Sender: daemon@bloom-beacon.MIT.EDU Organization: The Internet Lines: 65 Approved: ailist@ai.ai.mit.edu Date: Thu, 9 Jun 88 19:14 EDT From: hayes.pa@Xerox.COM Subject: Re: Consensus and Reality In-reply-to: "Bruce E. Nevin" 's message of Thu, 9 Jun 88 09:31:41 EDT Subject: Consensus and Reality To: bnevin@cch.bbn.com cc: ailist@ai.ai.mit.edu, hayes.pa@Xerox.COM, jmc@sail.stanford.edu, bn@cch.bbn.com I suspect we agree, but are using words differently. Let me try to state a few things I think and see if you agree with them. First, what we believe ( know ) about the world - or, indeed, about anything else - can only be believed by virtue of it being expressed in some sort of descriptive framework, what is often called a `language of thought': hence, we must apprehend the world in some categorical framework: we think of our desks as being DESKS. Second, the terms which comprise our conceptual framework are often derived from interactions with other people: many - arguably, all - indeed were learned from other people, or at any rate during experiences in which other people played a central part. ( I am being deliberately vague here because almost any position one can take on nature/nurture is violently controversial: all I want to say is that either view is acceptable. ) None of this is held as terribly controversial by anyone in AI or cognitive science, so it may be that by your lights we are all consensual realists. I suspect that the difference is that you think that when we talk of reality we mean something more: some `absolute Reality', whatever the hell that is. All I mean is the physical world in which we live, the one whose existence no-one, it seems, doubts. One of the useful talents which people have is the ability to bring several different categorical frameworks to bear on a single topic, to think of things in several different ways. My CRT screen can be thought of ( correctly ) as an ensemble of molecules. But here is where you make a mistake: because the ensemble view is available, it does not follow that the CRT view is wrong, or vice versa. You say: BN> From one very valid perspective there is no BN> CRT screen in front of you, only an ensemble of BN> molecules. No: indeed, there is a collection of molecules in front of me, but it would be simply wrong to say that that was ALL there was in front of me, and to deny that this collection didnt also comprise a CRT. That perspective isnt valid. Perhaps we still agree. Let me in turn agree with something else which you seem to think we realists differ from: neither of these frameworks IS the reality. Of course not: no description of something IS that thing. We dont mix up beliefs about a world with the world itself: what makes you think we do? But to say that a belief about ( say ) my CRT is true is not to say that the belief IS the CRT. I suspect, as I said in my earlier note, that you have a stronger notion of Truth and Reality than I think is useful, and you attribute deep significance to the fact that this notion - "absolute Reality" - is somehow forever ineffable. We can never know Reality ( in your sense ): true, but this could not possibly be otherwise, since to know IS to have a true belief, and a belief is a description, and a description is couched in a conceptual framework. And as Ayer says, it is perverse to attribute tragic significance to what could not possibly be otherwise. When your discussion moves on to the evolution of nature, citing Pask, Winograd and Flores and other wierdos, Im afraid we just have to agree to silently disagree. Pat