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Do thought experiments really uncover new scientific truths?

#1
C C Offline
https://aeon.co/essays/do-thought-experi...fic-truths

EXCERPT: . . . Today, most scientists and philosophers believe that there is only one reliable way to learn about the world, namely, to poke and prod at it – the view that philosophers call empiricism. [...] But as Galileo has shown, there seem to be exceptions to this rule. [...] Thought experiments, as they’re known, are an exercise of pure imagination. We think about some particular arrangement of things in the world, and then work out what the consequences would be. In doing so, we seem to learn something about the laws of nature. Thought experiments have played a crucial role in the history of physics. Galileo was the first great master of the thought experiment; Albert Einstein was another. [...]

If [philosopher James Robert] Brown is right – if Galileo successfully thought his way through to understanding something profound about the natural world – then it is important to know how, exactly, he pulled it off. Brown’s view is that thought experiments allow us to glimpse ‘universals’; that is, they let us discern universal truths about the natural world. In much the same way that we arrive at mathematical truths (by thinking about them), we can also arrive at certain truths about nature.

In other words, although the world is full of physical stuff, occupying space and persisting over time, some truths about the physical world have a very un-physical flavour. They resemble mathematical truths, seeming to exist outside of space and time. These truths, Brown believes, can be intuited a priori, without the need for observation or experiment. It’s an idea that goes back to Plato, and indeed Brown cheerfully describes himself as a Platonist.

For several decades now, John Norton, a philosopher at the University of Pittsburgh, has defended the empiricist camp against Brown’s Platonism. Norton believes that thought experiments, far from offering a glimpse into a realm of Platonic truths, are simply elegantly crafted arguments that bring vivid pictures to the mind’s eye. They do not produce new knowledge, he says, other than what one might deduce from analysing the knowledge already implicitly contained in the argument’s own premises. Thought experiments, as he wrote in a paper in 1996, ‘open no new channels of access to the physical world’. Consider again the Galileo case....

MORE: https://aeon.co/essays/do-thought-experi...fic-truths
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#2
Syne Offline
As far as science is concerned, thought experiments help us decide what and how to prod empirically. While they may be the initial insight, only verification leads to "scientific truths."
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#3
Yazata Offline
Aren't mathematical models essentially formalized thought experiments?
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#4
Yazata Offline
(Dec 22, 2017 03:32 AM)C C Wrote: Today, most scientists and philosophers believe that there is only one reliable way to learn about the world, namely, to poke and prod at it – the view that philosophers call empiricism.

'Empiricism' refers to the idea that we learn about the world by sensory experience. So...

1. In order to be empirical, must science conduct experiments where reality is indeed 'poked and prodded'? Where variables are intentionally changed and the results of changing them observed?

2. Or can science proceed merely by passive observation? (That's what astronomers seem to do.)

I guess that one way of harmonizing 1. and 2. would be to say that both of them involve causal interaction with what is observed. The astronomer is observing photons put out by distant astronomical objects, such that there is a continuous (if one-way) causal chain between the astronomer and the thing observed.

But I still think that I'd want to say that non-experimental forms of empiricism are possible.

Quote:Thought experiments, as they’re known, are an exercise of pure imagination.

I think that I disagree with that. Thought experiments employ concepts and relationships previously acquired empirically, through sensory experience. (Or their variations.) Then the thought experiment explores the implications of what has been observed or of changing this or that about it. In the total absence of any sensory contact with reality, it's hard to imagine what form imagination would take.

Quote:We think about some particular arrangement of things in the world, and then work out what the consequences would be. In doing so, we seem to learn something about the laws of nature.

We observe reality. We abstract relationships between observed variables from our observations. (That's often expressed in mathematical form). Then we can imagine the implications of our relationships (equations of theoretical physics) in new situations that haven't been observed.

If our empirically-derived abstractions are correct (a crucial 'if') then exploring their implications may indeed lead to new knowledge.

Quote:If [philosopher James Robert] Brown is right

I've often found myself disagreeing with Brown. He's interesting though.

Quote:if Galileo successfully thought his way through to understanding something profound about the natural world – then it is important to know how, exactly, he pulled it off. Brown’s view is that thought experiments allow us to glimpse ‘universals’; that is, they let us discern universal truths about the natural world.

We often seem to treat physical law that way, as Platonic-style universals. I'm still not sure what physical law is, so I think that it might be premature to jump to metaphysical conclusions.

As I suggested above, what I think what physicists do (this isn't universal in science, biologists don't proceed this way) is make observations and conduct experiments. They note relationships between variables. They generalize those relationships into mathematical form and if those expectations are confirmed sufficiently (whatever that means, the problems of induction arise here) they start thinking of their mathematical equation as a fundamental principle of nature. My point is that apart from the abstraction and formalization steps (which seem to embody metaphysical assumptions) it's all still drawn from experience and impeccably empirical.

One can advance the more metaphysical argument that this wouldn't work unless there really is an underlying regularity in nature that the physics is successfully modeling. I think that's true. So one can argue that these underlying truthmakers, the regularities in nature that physics models and that make the propositions of physics true, are in fact the universals.

Quote:In much the same way that we arrive at mathematical truths (by thinking about them), we can also arrive at certain truths about nature.

I wonder what kind of mathematics a being with no senses, no contact with physical reality, could possibly spin out of pure consciousness itself (consciousness of... what?) I suspect that mathematics might be impossible for such a being.

Quote:In other words, although the world is full of physical stuff, occupying space and persisting over time, some truths about the physical world have a very un-physical flavour. They resemble mathematical truths, seeming to exist outside of space and time.

I think that's the result of the abstraction and formalization that theoretical physics applies to its empirical raw material. Or the underlying metaphysical nature of reality itself. Or something... (I don't think that anyone really understands this.)

Quote:These truths, Brown believes, can be intuited a priori, without the need for observation or experiment.

I don't think so. (Brown seems to be channeling Descartes' ghost.)

I think that what physics does is abstract, generalize and formalize. That succeeds in giving us scientific knowledge when nature cooperates. It works very well in physics, which seems to be relatively simple, such that simple mathematical generalizations hold true. It hasn't worked at all in the so-called "social sciences" where no underlying law-like regularities seem to exist.

The Scientific Revolution succeeded in part because the initial attempts to create a new mechanics were applied to (physically speaking) the simplest cases. The motion of the planets in the sky (thanks astrologers) and simple cases like billiard balls striking one another or rolling metal balls down inclined planes. It took centuries more before the new science could get a grip on chemistry or biology, and only then after abandoning lots of its earlier Galileo and Newton style methodology (seeking mathematical universals).

Quote:For several decades now, John Norton, a philosopher at the University of Pittsburgh, has defended the empiricist camp against Brown’s Platonism.

I'd question how influential Brown is.

Quote:Norton believes that thought experiments, far from offering a glimpse into a realm of Platonic truths, are simply elegantly crafted arguments that bring vivid pictures to the mind’s eye. They do not produce new knowledge, he says, other than what one might deduce from analysing the knowledge already implicitly contained in the argument’s own premises.

Assuming that the abstractions, generalizations and formalizations of theoretical physics do in fact model the deep structure of reality, then working out their implications would seem to me to lead to the possibility of new knowledge. Certainly Norton can argue that it already implicitly 'existed' in the original formalization, but if no human being had ever recognized it previously, it would still be new to us.

Quote:Thought experiments, as he wrote in a paper in 1996, ‘open no new channels of access to the physical world’.


I agree. But...
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#5
Syne Offline
Empiricism is just knowledge derived by observation, whether or not we can interact to change variables. So there's no need to distinguish observation from prodding, as prodding is just a more direct observation. All empirical observations only seek to find repeatable patterns in nature. Being able to interfere with those patterns just provides more info. But experiments can be wholly observational. We can make observations, hypothesize about mechanisms, make predictions to test the hypothesis, make further/more detailed observations, and then arrive at a conclusion about the validity of a hypothesis. For example, many of the verifications of GR are wholly observational, like gravitational lensing, the orbit of Mercury, etc..

Thought experiments differ in that they seek to examine things that cannot be observed at the time, or at all. While they can be tests of hypotheses based on observation, they typically do not have access to the further observations necessary for such a test...so imagination must suffice. They don't usually make predictions, because they cannot be tested against observation. Where scientific modeling is commonly used to simplify and explain, thought experiments do not offer compelling conclusions. They only offer insights.

We can't determine by observation the state of Schrodinger's cat, the reality of the ladder paradox, the possibility for philosophical zombies, or the full ramifications of a brain in a vat. So we must interject imagination to make logical tests where empirical ones are not available.
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#6
C C Offline
Quote:In much the same way that we arrive at mathematical truths (by thinking about them), we can also arrive at certain truths about nature. [The author referencing James Robert Brown's views]


The basics of quantity and calculation were historically abstracted from phenomena and activity in the empirical or sensible world (the dawn of civilization and trade required measurement dependent transactions and record-keeping). But once its foundational characteristics and axioms were introduced into play, the evolution of later advanced mathematics might be construed as floating on its own. Or at least those endeavors which could be deemed pure mathematics.

Areas of applied mathematics, in the course of potential feedback from their use in practical skills and pursuits, could arguably still be created via the earliest way or perhaps even modified by that interaction with the contingent environment of humans. Superstring theory has spurred innovations, but since it is purely hypothetical and currently untestable it might as much be an example of an abstraction inspiring more abstractions, instead of new maths generated in an applied / empirical context. However, superstrings did come about to "solve" problems concerning the cosmos (barring general relativity and QM themselves and their incompatibility difficulties being just another useful fiction / abstraction rather than corresponding to empirically real circumstances).

Quote:If [philosopher James Robert] Brown is right – if Galileo successfully thought his way through to understanding something profound about the natural world – then it is important to know how, exactly, he pulled it off. Brown’s view is that thought experiments allow us to glimpse ‘universals’; that is, they let us discern universal truths about the natural world.

Is induction (reasoning from particular facts to general principles) a thought experiment? It seems more like one of the already existing tools optionally utilized by a thought experiment. I'm skeptical that "thought experiments" are always trying to output a universal. A generalization is also more of a way to "understand" particulars -- to anticipate/predict, group, manipulate them, and so forth -- almost a prescription for how to interpret or what to do, though that doubtless still falls under the liberal, contested, and resultingly fuzzy / obscure meanings of "knowledge".

It requires intellect / creativity to design an experiment -- to concoct a plan for interrogating some aspect of nature, rather than the cataloguing of what observationally exists in the world via passive encounters. But that kind of recruitment of reasoning and inventiveness doesn't seem to jibe with a thought experiment, unless the latter is by definition intended to not wholly be confined to armchair reflection or description on paper. Or if virtually running a lab investigation in the head (before the fact) to speculate on what will fall out of it should count as a thought experiment.

Otherwise a thought experiment is like a simulation carried out by the brain or manually guided by the brain's activity, that is either exploring the depths of or is being regulated by already existing, accepted or approved premises, principles, ideas, data, rules, schemes, doctrines, etc. In that sense any "new" knowledge analytically discovered in the internal structure of the concepts themselves or that is outputted by a mental "simulation" or process which they manage... Would indeed already be contained within those abstract forms or their working / interacting combinations [as rival John Norton apparently contends]. But OTOH, if "loose ends" or incoherent areas are discovered in the exploration and use of them which engenders a revision or forces creation of a new field of inquiry, or the synthesis of multiple ideas results in a radically new concept unlike any before, then it might be contended that truly valid novelties have been yielded or forecast from the existing constructs / information alone.

The oddities of quantum physics probably weren't contained in or predicted by the traditional or earliest formulations of philosophical naturalism or its employed version of methodological naturalism. So maybe a quick, tentative example of empirical reality intruding in upon a regulating concept or set of principles and forcing adjustments or an overhaul of that governing construct.

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#7
RainbowUnicorn Offline
(Dec 22, 2017 03:32 AM)C C Wrote: https://aeon.co/essays/do-thought-experi...fic-truths

EXCERPT: . . . Today, most scientists and philosophers believe that there is only one reliable way to learn about the world, namely, to poke and prod at it – the view that philosophers call empiricism. [...] But as Galileo has shown, there seem to be exceptions to this rule. [...] Thought experiments, as they’re known, are an exercise of pure imagination. We think about some particular arrangement of things in the world, and then work out what the consequences would be. In doing so, we seem to learn something about the laws of nature. Thought experiments have played a crucial role in the history of physics. Galileo was the first great master of the thought experiment; Albert Einstein was another. [...]

If [philosopher James Robert] Brown is right – if Galileo successfully thought his way through to understanding something profound about the natural world – then it is important to know how, exactly, he pulled it off. Brown’s view is that thought experiments allow us to glimpse ‘universals’; that is, they let us discern universal truths about the natural world. In much the same way that we arrive at mathematical truths (by thinking about them), we can also arrive at certain truths about nature.

In other words, although the world is full of physical stuff, occupying space and persisting over time, some truths about the physical world have a very un-physical flavour. They resemble mathematical truths, seeming to exist outside of space and time. These truths, Brown believes, can be intuited a priori, without the need for observation or experiment. It’s an idea that goes back to Plato, and indeed Brown cheerfully describes himself as a Platonist.

For several decades now, John Norton, a philosopher at the University of Pittsburgh, has defended the empiricist camp against Brown’s Platonism. Norton believes that thought experiments, far from offering a glimpse into a realm of Platonic truths, are simply elegantly crafted arguments that bring vivid pictures to the mind’s eye. They do not produce new knowledge, he says, other than what one might deduce from analysing the knowledge already implicitly contained in the argument’s own premises. Thought experiments, as he wrote in a paper in 1996, ‘open no new channels of access to the physical world’. Consider again the Galileo case....

MORE: https://aeon.co/essays/do-thought-experi...fic-truths

natural evolution.
is it possible for humanity to form atomic science laws without building a bomb ?
etc etc etc...
the empirical part of invention and science is always required.
with fast evolving science, the empirical part probably lags behind a little.

how are we going to travel faster than light speed if we never invent a working example for us to draw conclusive laws from ?
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