kube@cogsci.berkeley.edu (Paul Kube) (01/01/70)
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. Whew. I thought we were gearing up for a substantive disagreement about whether or not scientific statements can be true. Now it's clear we just disagree about what `theory' means, and I don't want to take time to argue about that. (I certainly agree that manners of looking at the world are neither true nor false.) >It is this conceptual model -- mass, F=ma, and the >Newtonian reference frame -- that make up the theory of Newtonian Physics. >Is it true? This still seems (to me) a strange way of looking at a model. >Can it produce true statements? Yes. >Have I clarified my position any? Yes, and thanks for it. 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. --Paul kube@berkeley.edu, ...!ucbvax!kube
biep@cs.vu.nl (J. A. "Biep" Durieux) (01/01/70)
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 a >conceptual model. Science is a human activity, done by humans to help them >understand their environment -- which means to make conceptual models of >their environment, which I call theories. It is not done in the absence of >an observer -- statements by themselves do not make a theory. This is the >objection I have to Biep's "mechanization" of science. OK, that's a definitional matter, then. I take "theory" to be just a set of statements, with nothing but operational semantics for the primitive terms. (So electric current *is* what I, or the computer, measures.) Of course no program makes sense (well, perhaps to itself?) unless there is someone to say "These numbers are the salaries of the employees". But then my postings don't make sense either unless there is someone who says what all those little squiggles on your screen mean. I do believe I have some sort of "intrinsic semantics", but I also believe others can't infer it other than by just looking at my behaviour and my statements and trying to guess. In other words: the computer will (may) not understand what it does, but we may be unable to tell whether it does. And for my purpose (graduating), that's (way more than) enough. >I think it is safe to say that most of us have >conceptions of acceleration and force, but mass is something we experience >only through F=ma. 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.. :-)) >Have I clarified my position any? More or less, yes. Let me wait till you have answered Paul Kube's questions. BTW, as the new schol year has begun, people expect me to do funny things which lots of students in a big room, so I suppose I'll slow down my usenet pace somewhat. Things will come, however (DV), it may only take more time. Please bear. -- Biep. (biep@cs.vu.nl via mcvax) My F-key has autorepeat
kube@cogsci.berkeley.edu (Paul Kube) (08/26/87)
Bob Meyers writes: >Are we still talking about scientific theories? What does it mean to >say a scientific theory is more likely to be true? A theory, scientific or otherwise, is a statement about how things are. Like any statement, it is true iff things are the way it says they are. That's all there is to it... What relative likelihood of truth of theories amounts to then is just a matter of how you want to do probability theory. Typically, a scientific theory will make claims about both observable and unobservable entities. It's harder to evaluate a theory's claim about the unobservable ones; usually one does something like taking confirmation of predictions in carefully designed experiments as evidence for the unobservables. It's hardest when two theories agree on all the observables and disagree on the unobservables; how to decide now which theory is more likely to be true? This, of course, is where Ockham's razor is supposed to come in. --Paul kube@berkeley.edu, ...!ucbvax!kube
myers@tybalt.caltech.edu (Bob Myers) (08/28/87)
Paul Keube ( :-) ) writes: >A theory, scientific or otherwise, is a statement about how things >are. Like any statement, it is true iff things are the way it says >they are. That's all there is to it... What relative likelihood of >truth of theories amounts to then is just a matter of how you want to >do probability theory. Interesting. I don't agree. Firstly, I think a theory is more than "a" statement. Continental Drift is not a theory, but Plate Tectonics is. Now, is plate tectonics "true"? Are things the way plate tectonics say they should be? Certainly not exactly. Plate tectonics is a model of geological processes, necessarily much simplified from what "actually" is going on. And this is certainly not specific to geology. Is Newtonian Physics true? Things are not the way it says they are, under some conditions. I would say that is where the model breaks down. But if I'm concerned about whether or not it is "true", I would say that *no* scientific theory is true, because they are always simplifications of what is observed. Didn't you mention that there is a *lot* of information thrown away in the F=ma mapping? I think people try to introduce the idea of "truth" in science because they are used to talking about such things in philosophy and religion. The concept of "Laws of Nature" is part of this. "Laws of Nature" date back to the Enlightenment, and aren't much favored today. ------------------------------------------------------------------------------- Bob Myers myers@tybalt.caltech.edu {rutgers,amdahl}!cit-vax!tybalt.caltech.edu!myers
greg@mind.UUCP (Greg Nowak) (08/28/87)
In article <3800@cit-vax.Caltech.Edu> myers@tybalt.caltech.edu.UUCP (Bob Myers) writes: >Paul Keube ( :-) ) writes: >>A theory, scientific or otherwise, is a statement about how things >>are. Like any statement, it is true iff things are the way it says >>they are. That's all there is to it... What relative likelihood of >>truth of theories amounts to then is just a matter of how you want to >>do probability theory. >Interesting. I don't agree. Firstly, I think a theory is more than "a" >statement. Continental Drift is not a theory, but Plate Tectonics is. Continental Drift, as articulated by Wegener, was more than "a" statement. I have to call you on this one, Bob -- can you explain why CD isn't (or do you mean "wasn't") a theory, but PT is? (No fair saying CD was 'wrong' ... ;-) >Now, is plate tectonics "true"? Are things the way plate tectonics say >they should be? Certainly not exactly. Plate tectonics is a model of >geological processes, necessarily much simplified from what "actually" >is going on. And so too was Continental Drift a model of geological processes, necessarily much simplified from what "actually" is going on. We must be careful not to restrict our definition of "theory" to only those families of ideas which are currently accepted ... You wouldn't want to get caught calling Newton a lousy theorist, would you? ;-) greg -- "You're not the only soul accused of hit and run Tire tracks all across your back I can see that you had your fun" ...seismo!princeton!mind!greg
myers@tybalt.caltech.edu (Bob Myers) (08/28/87)
In article <1191@mind.UUCP> greg@mind.UUCP (Greg Nowak) writes: >In article <3800@cit-vax.Caltech.Edu> myers@tybalt.caltech.edu.UUCP (Bob Myers) writes: > >>Interesting. I don't agree. Firstly, I think a theory is more than "a" >>statement. Continental Drift is not a theory, but Plate Tectonics is. > >Continental Drift, as articulated by Wegener, was more than "a" >statement. I have to call you on this one, Bob -- can you explain why >CD isn't (or do you mean "wasn't") a theory, but PT is? (No fair >saying CD was 'wrong' ... ;-) You are correct, and I didn't say what I meant. By continental drift above, I meant just the idea that the continents move and once fitted together across the Atlantic. I used it as an example due to a previous when I was replying to Biep. Is that clear now? ------------------------------------------------------------------------------- Bob Myers myers@tybalt.caltech.edu {rutgers,amdahl}!cit-vax!tybalt.caltech.edu!myers
kube@cogsci.berkeley.edu.UUCP (08/31/87)
In article <3800@cit-vax.Caltech.Edu> myers@tybalt.caltech.edu.UUCP (Bob Myers) writes: >Paul Keube ( :-) ) writes: >>A theory, scientific or otherwise, is a statement about how things >>are. Like any statement, it is true iff things are the way it says >>they are. >Interesting. I don't agree. Firstly, I think a theory is more than "a" >statement. Look, statements can be pretty long; but if you prefer to think of a theory as a set of statements instead, that's fine. The theory is true iff each of the statements it makes are true. Or what are you getting at here? I'm not saying that every statement is a theory, only the converse. >Now, is plate tectonics "true"? Are things the way plate tectonics say >they should be? Certainly not exactly. >And this is certainly not specific to geology. Is Newtonian Physics >true? Things are not the way it says they are, under some conditions. If Newtonian Physics says "F=ma, period" then it's false, since there are circumstances in which F!=ma. If it says "F=ma to a real good approximation at reasonable masses and velocities, etc." then it's not false on that account. It can be nontrivial to figure out what statements are being made; in this case I guess Newton, though not 20th century college physics instructors who teach Newton, should be held to "F=ma, period". I'd think it's uncharitable to interpret any theory as making more precise statements than its framers intend. >I think people try to introduce the idea of "truth" in science because >they are used to talking about such things in philosophy and religion. >The concept of "Laws of Nature" is part of this. "Laws of Nature" date >back to the Enlightenment, and aren't much favored today. Let me reply to one ad hominem with another. I think that people respond neurotically to the mention of "truth" because of experiences of oppression at the hands of institutions or individuals who, in some sociopolitical context, have their position of power because of a supposed priveleged access to truth. This, however, is not a problem with the concept of truth, but with cultural attitudes towards it. What we should learn from having tried to do theology, philosophy, and science is some idea of how hard it is to get nearer the truth, and what kind of open-ended project of cooperation and criticism it seems to take. --Paul kube@berkeley.edu, ...!ucbvax!kube
myers@tybalt.caltech.edu (Bob Myers) (09/04/87)
In article <20371@ucbvax.BERKELEY.EDU> kube@cogsci.berkeley.edu.UUCP (Paul Kube) writes: > >Look, statements can be pretty long; but if you prefer to think of a theory >as a set of statements instead, that's fine. The theory is true iff each >of the statements it makes are true. Or what are you getting at here? >I'm not saying that every statement is a theory, only the converse. 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 a conceptual model. Science is a human activity, done by humans to help them understand their environment -- which means to make conceptual models of their environment, which I call theories. It is not done in the absence of an observer -- statements by themselves do not make a theory. This is the objection I have to Biep's "mechanization" of science. >If Newtonian Physics says "F=ma, period" then it's false, since there >are circumstances in which F!=ma. If it says "F=ma to a real good >approximation at reasonable masses and velocities, etc." then it's >not false on that account. F=ma (at reasonable ... etc.) is a true statement that Newtonian Physics allows one to make. It is not the theory, though it is an important part of it. One really important part is the concept of mass -- which is introduced by Newtonian Physics. What is mass? F=ma is, in the end, a definition of mass. What makes it useful is that it is consistent in any Newtonian reference frame (which is the other important concept of Newtonian Physics). I think it is safe to say that most of us have conceptions of acceleration and force, but mass is something we experience only through F=ma. It is this conceptual model -- mass, F=ma, and the Newtonian reference frame -- that make up the theory of Newtonian Physics. Is it true? This still seems (to me) a strange way of looking at a model. Can it produce true statements? Yes. Have I clarified my position any? ------------------------------------------------------------------------------- Bob Myers myers@tybalt.caltech.edu {rutgers,amdahl}!cit-vax!tybalt.caltech.edu!myers
sarge@thirdi.UUCP (Sarge Gerbode) (09/09/87)
In article <889@klipper.cs.vu.nl> biep@cs.vu.nl (J. A. "Biep" Durieux) writes: >>I think it is safe to say that most of us have >>conceptions of acceleration and force, but mass is something we experience >>only through F=ma. > >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.. :-)) I think Bob Myers is right here. At least that corresponds to *my* experience. I wouldn't experience aomething as having mass unless it resisted a force I applied to it. A feather offers little resistance, so we say it is not massive. A lead weight offers greater resistance, so we experience it as more massive. More precisely, at the phenomenological level, mass is experienced as aq resistance to *acceleratd translation* (acceleration of an object as a whole in a certainj direction), while *solidity* and *viscosity* is experienced as resistance to *transformation* (change of shape). Friction is experienced as resistance to *simple translation*. Phenomenologically, the solidity and massiveness of the universe around us is experienced through the resistance the universe gives to our efforts to change it. -- "Absolute knowledge means never having to change your mind." Sarge Gerbode Institute for Research in Metapsychology 950 Guinda St. Palo Alto, CA 94301 UUCP: pyramid!thirdi!sarge
myers@tybalt.caltech.edu (Bob Myers) (09/16/87)
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