On the other hand, there is a huge and highly charged debate going on in current physics and cosmology, as to whether string theory and the speculative multiverse that flows from it, is really a matter for science or not. On the Nay side are those who say that these ideas can never be falsified even in principle, as they concern matters which are by definition outside the universe. On the Yay side are those who say that, because of the compelling nature of the mathematics and the solutions that these models offer to many intractable problems, then such speculations should be regarded as within the ambit of science. — Wayfarer

Sorry I came late to this discussion. I looked through the other posts. I don't think what I say will duplicate others, although several people have touched on issues discussed in this post.

What Wayfarer says, above, is something I've thought about a lot. It does seem to me that if something can't be falsifiable, even in theory, it's not science. It's either metaphysics or meaningless. On the other hand, if the mathematics and the solutions that these models offer solutions to many intractable problems, why isn't that an example of falsifiability?

Then, of course, there are the assumptions that other people do in fact exist, that there is actually a real, external world that continues to exist without our participation, that there are "laws" that are explicable mathematically, etc. — darthbarracuda

@tim wood steered me towards "An Essay on Metaphysics," by R.G. Collingwood. I really like it, at least partly because his definition of "metaphysics" is similar to mine, although different from many others on this forum and elsewhere. Here's what he says:

"Metaphysics is the attempt to find out what absolute presuppositions have been made by this or that person or group of persons, on this or that occasion or group of occasions, in the course of this or that piece of thinking."

Here's what he says about absolute propositions:

"An absolute presupposition is one which stands, relatively to all questions to which it is related, as a presupposition, never as an answer."

"Absolute presuppositions are not verifiable. This does not mean that we should like to verify them but are not able to; it means that the idea of verification is an idea which does not apply to them...."

Here are some statements I think are absolute presuppositions:

• The outside world exists.
• There is an objective reality.
• Every event has a cause. There are no miracles. Causes are naturalistic.
• Truth is the ultimate goal of science and philosophy.
• The world behaves the same now as it did in the past and the same here as it does elsewhere in the universe.

What Wayfarer says, above, is something I've thought about a lot. It does seem to me that if something can't be falsifiable, even in theory, it's not science. It's either metaphysics or meaningless. On the other hand, if the mathematics and the solutions that these models offer solutions to many intractable problems, why isn't that an example of falsifiability? — T Clark

Popper devised the criterion of falsifiability to distinguish empirical hypotheses from speculative ideas that could not in principle be tested against some observation. Mathematics is a different matter as it concerns purely mathematical or logical facts.

As to why speculative mathematical theories such as string theory are scientific matters or not - obviously a highly vexed question. Have you heard of a book called Farewell to Reality, by Jim Baggott? It's a sceptical analysis of the current state of physics speculation by a physics-educated science writer. That and Peter Woit's book Not Even Wrong are both highly critical of string theory and its proponents.

I take issue with every one of your 'absolute presuppositions', as they're not actually part of the curriculum of metaphysics proper (especially #3). I think what you're doing there is conflating metaphysical naturalism with metaphysics proper. Metaphysical naturalism is the commitment of science to seeking natural explanations and causes, which is all well and good. However when that becomes a global statement about what is real, what kinds of causes exist, then you're no longer in the territory of metaphysical naturalism, but of metaphysics proper. You're making statements about 'the nature of reality' on the basis of naturalism. And that's susceptible to the 'metal detector' analogy that Feser gives in his criticism of 'scientism':


1. The predictive power and technological applications of the natural sciences are unparalleled by those of any other purported source of knowledge.

2. Therefore what science reveals to us is all that is real.

Compare:

1. Metal detectors have had far greater success in finding coins and other metallic objects in more places than any other method has.

2. Therefore what metal detectors reveal to us (e.g. coins, gold nuggets) are all that is real.

Metal detectors are keyed to those aspects of the natural world susceptible of detection via electromagnetic means (or whatever). But however well they perform this task -- indeed, even if they succeeded on every single occasion they were deployed -- it doesn't follow that there are not aspects of the natural world other than the ones they are sensitive to.

Popper devised the criterion of falsifiability to distinguish empirical hypotheses from speculative ideas that could not in principle be tested against some observation. Mathematics is a different matter as it concerns purely mathematical or logical facts. — Wayfarer

I guess what I was trying to say is, if I can't directly observe a phenomenon, but it's existence explains things I can observe, which is what I thought you were describing, then it may be reasonable for me to infer it's existence.

I think what you're doing there is conflating metaphysical naturalism with metaphysics proper. — Wayfarer

Not sure I understand the distinction. Collingwood is talking about absolute presuppositions "made by this or that person or group of persons, on this or that occasion or group of occasions, in the course of this or that piece of thinking." I interpret this as similar to what I have said in previous discussions - metaphysical approaches are chosen based on usefulness, not some absolute correspondence with reality. As he says, "Absolute presuppositions are not verifiable."

I guess what I was trying to say is, if I can't directly observe a phenomenon, but it's existence explains things I can observe, which is what I thought you were describing, then it may be reasonable for me to infer it's existence. — T Clark

It sounds a simple principle - but what about 'bubble universes' or 'multiple worlds'? Is it 'reasonable' to posit the reality of those? That is the salient point here.

Collingwood is talking about... — T Clark

If Collingwood is writing from within the Western philosophical tradition, then he's talking in terms of Aristotelian metaphysics, which has a definite domain of discourse. Sure it's 'general' in the sense of being a 'philosophy of first principles', but at the same time, it articulates the issues using a particular kind of vocabulary and set of concepts.

It sounds a simple principle - but what about 'bubble universes' or 'multiple worlds'? Is it 'reasonable' to posit the reality of those? That is the salient point here. — Wayfarer

Actually, the bubble universes was what set me off down this path. If I understood him correctly, @apokrisis was talking about them as an effect of one current understanding of inflation during, or before, or whatever, the big bang. If a phenomenon is required in order to understand something that is observable, even though it isn't, then it seems to me it meets the requirement as suitable for scientific evaluation.

If Collingwood is writing from within the Western philosophical tradition, then he's talking in terms of Aristotelian metaphysics, which has a definite domain of discourse. Sure it's 'general' in the sense of being a 'philosophy of first principles', but at the same time, it articulates the issues using a particular kind of vocabulary and set of concepts. — Wayfarer

Collingwood starts out talking about Aristotle, but it doesn't seem that hard to understand what he is trying to say. Unless I am misunderstanding something, his statements speak for themselves. I'll go back and read again.

Just to be clear, I have a lot of confidence in the way you see things. It's been a big help to me in the past. That makes me want to go back and re-examine what I'm saying.

3. Pluralism: Ontologies are dependent on theories that posit them, and they are all real just to the extent to which their respective theories are taken seriously. — SophistiCat

That seems question begging about how you would define "real" here. How does it not wind up sounding idealist or subjective - that is, anti-realist?

And an even greater difficulty. The least action principle is an example of how science does appear to discover a unity, rather than a pluralism, at the deepest ontic level.

You can try any theory you like ... but the historical evidence is that it needs to be based on the least action principle with its focus on closure and symmetry.

Very kind of you to say so. I will see if I can find a bit of time to read that Collingwood essay, it has been recommended by quite a few posters.

That seems question begging about how you would define "real" here. How does it not wind up sounding idealist or subjective - that is, anti-realist? — apokrisis

Well, I am not too concerned with how this sounds, but what question is being begged here?

And an even greater difficulty. The least action principle is an example of how science does appear to discover a unity, rather than a pluralism, at the deepest ontic level. — apokrisis

That to me suggests a structural relationship between theories. One is tempted to conclude that what accounts for this common trope is that in their different ways these theories all get a hold on the same truth. But one should always keep a bit of wary skepticism and not be totally seduced by theoretical elegance. That way lies dogmatism.

Probably just simpler to say science believes there is ontically one world, but epistemically any number of models of it.

So instrumentalism and pluralism would be the same thing I would suggest.

You may have been making the point that every model advances its own ontic commitments. They talk of “real” entities like temperature or charge. But that wasn’t clear, and would still be pragmatism anyway.

what they are doing commits them to nothing other than constructing models — ProcastinationTomorrow

Even that implies a fair amount of metaphysics, I think. Who or what are "they", what is a "commitment", what is "construction", what is a "model"?

It's not really possible to think at all without taking a good deal for granted, and actually what's taken for granted is a bunch of fairly boring stuff that most people agree with and that comports with common sense.

However, one understand what those scientists mean: they mean they're not committing themselves to anything particularly bizarre or unusual.

That's a fair point. I guess I am just not very serious about ontology: I am more interested to know what the world is like than what "stuff" it is made from or what "things" it ought to be parsed into - which puts me more on the side of instrumentalists and pragmatists. But I am also on the side of common sense and natural language in wanting to say that yes, there are chairs and cats and temperature and charge. That's just what "existence" means to us.