Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!cmcl2!rutgers!ucla-cs!cit-vax!tybalt.caltech.edu!myers From: myers@tybalt.caltech.edu (Bob Myers) Newsgroups: sci.philosophy.tech Subject: Re: Truth of theories Message-ID: <3996@cit-vax.Caltech.Edu> Date: Wed, 16-Sep-87 07:19:35 EDT Article-I.D.: cit-vax.3996 Posted: Wed Sep 16 07:19:35 1987 Date-Received: Fri, 18-Sep-87 06:50:07 EDT References: <20297@ucbvax.BERKELEY.EDU> <20304@ucbvax.BERKELEY.EDU> Sender: news@cit-vax.Caltech.Edu Reply-To: myers@tybalt.caltech.edu.UUCP (Bob Myers) Organization: California Institute of Technology Lines: 83 Keywords: truth In article <20543@ucbvax.BERKELEY.EDU> kube@cogsci.berkeley.edu.UUCP (Paul Kube) writes: >In article <3893@cit-vax.Caltech.Edu> myers@tybalt.caltech.edu.UUCP (Bob Myers) writes: >>I'm saying that a theory is not a set of statements, but a manner of >>looking at the world that allows one to *make* true statements. > >>It is this conceptual model -- mass, F=ma, and the >>Newtonian reference frame -- that make up the theory of Newtonian Physics. > > But I'd like further clarification: What >exactly is left out of the theory of Newtonian Physics if we cast your >characterization of it into a statement: "There is mass, F=ma, and >there are Newtonian reference frames"? Or to put it another way: What >in a `conceptual model' isn't just a matter of what's believed by those >who adopt the model? I take it that what's believed is susceptible of >evaluation with respect to truth. The *results* of a theory can always be reduced to a set of statements. However, there is a fundamental conceptual reorganization involved in the creation of a theory that is seemingly ignored if one concentrates solely on the statements involved. Newtonian Physics requires one to look at the world in terms of masses, forces, and Newtonian reference frames. It is one way of viewing the world which is very successful on some levels. However, I don't think we should confuse the *conceptual nature* of *mass* with reality. In other words, I do *not* say that there *is* mass, merely that it is a useful concept within certain limitations (Newtonian reference frames, non-relativistic velocities primarily.) What is left out of your summary is the fact that Newtonian Physics is an idealization of reality, not reality itself. What is Real is the province of philosophy or religion, not science. Scientific philosophy should not be confused with science. In article <889@klipper.cs.vu.nl> biep@cs.vu.nl (J. A. "Biep" Durieux) writes: >Funny. For my feeling "mass" just *is* matter, and so very concrete to me >(My physics teacher didn't like me equating the two..), whereas "force" is >a much more esoteric notion for me. (I know what getting hit by a stone is, >however.. :-)) You're confusing symbols and reality, which is just what I've been talking about. Firstly, even under a Newtonian scientific philosophy, mass is a *property* of matter, its quantity, not the stuff itself. There are more properties of matter than mass (for example, charge). Secondly, even this doesn't hold under relativity. Mass increases when you near light speed, but has the amount of matter changed? Note that I am *not* talking about the conversion of energy to mass, but the fact that the mass of an object depends on your reference frame. A good measure of "amount of matter" should be invariant under a reference frame change, no? But note that "amount of matter" is a prior conception. There is no a priori reason to believe that there is a constant "amount of matter." This is precisely the problem. We create these abstractions like mass, assume they have actual reality related to some prior beliefs we have, and end up applying them to circumstances where that abstraction breaks down, all the while arguing about how it makes no sense. QM being the 'classical' example here, of course. Is light a wave or a particle? The answer is both, and neither. One *model* fits better for certain classes of light phenomena, the other for other classes. I think it is a real mistake to assume that nature has to fit in our narrow little models. Thus my statement that theories are not 'true'. A theory is a model which can approximate reality, sometimes quite well, but should not be confused with reality. We can use theories to make true statements, statements about real physical observables, but we cannot know the reality of the theory itself, or its unobservable conceptions like 'mass'. It is not 'susceptible to evaluation with respect to truth'. I have two problems with Biep's ideas. One is my comment about theories not existing in the absence of an observer. But the other has to do with the creation of abstractions like "mass". Biep, how is your mechanism going to discover these abstractions without having first been told about them? ------------------------------------------------------------------------------- Bob Myers myers@tybalt.caltech.edu {rutgers,amdahl}!cit-vax!tybalt.caltech.edu!myers