Why are the Sciences Empirical?

[Sunstone]

Yes, it is a philosophical statement and thereby not useful for understanding anything. No contradiction at all.

So please explain to me how it is possible for you to assert that something is or is not useful for understanding something without philosophizing?

 

[exchemist]

So please explain to me how it is possible for you to assert that something is or is not useful for understanding something without philosophizing?

Quite.

The whole of this thread is in fact a philosophy thread. Empiricism is a philosophical idea. Any decent scientist needs to be aware of the philosophical principles and assumptions that underlie the discipline. Science grew from natural philosophy and its foundations are philosophical.

I suppose it can be argued that this thread is not "useful" for understanding anything, but I'm afraid I would not agree. It seems to me that in any intellectual discipline one should be aware of the assumptions and methods it employs, and hence aware also of its scope of application and thus its limitations. In the case of science, these assumptions and methods are philosophical.

Failure to appreciate this risks a narrowing of the mind, due to being unable to see that there are other ways of approaching the world and our experience of it, besides those of science. One sees this narrowing of the mind in the attitude of some popularisers of science today.

 

[Subduction Zone]

Science is hardly atheistic. My aunt was a deeply religious woman and she was a scientist. There are scientists who are atheists, scientists who are agnostic, scientists who are religious, and scientists who don't engage in the question.

Science is empirically oriented because observation and experience in the old days simply seemed to be highly trustworthy -- more trustworthy than, say, logic (since people often reason badly). Today we can add that empiricism has produced result well beyond any other philosophy or religion, in the way of life easing technology and modern medicine.

The sciences are "atheistic" in the sense that they do not invoke a god. They are not "atheistic" in the sense of claiming that there is no god or even that there is any evidence against a god. One often hears the term "atheistic evolution". But if one uses that term then they should be using the qualifier "atheistic" for everything in the sciences. It should be "atheistic gravity", "atheistic organic chemistry" , "atheistic petroleum geology". When some persons' false beliefs are refuted by the sciences they tend to call that branch of science "atheistic" and that leads to the misconception that the sciences try to disprove God.

 

[Polymath257]

So please explain to me how it is possible for you to assert that something is or is not useful for understanding something without philosophizing?

It is pretty similar to how I know there is a chair in front of me without philosophizing about what 'existence' means.

For example, suppose there is a mathematical result that I don't feel like I understand. Which is better? To philosophize about it? Or to explore other aspects of the related mathematics to put it into context? For me, the answer is clearly the latter.

Metaphysics is fine for drinking with friends. But to think it actually helps at all with understanding is, as far as I can tell, a great mistake. Instead, it gives the illusion that we are thinking deeply when we are actually just rearranging our prejudices.

So, something is helpful with understanding if, when I do it or learn it, I understand better. It really is that simple.

The point is that not all thought is philosophizing, which has to do with generalities and overall methods. Such tend to be useless in practice. Instead, look and explore and think about what the evidence says.

 

[Sunstone]

It is pretty similar to how I know there is a chair in front of me without philosophizing about what 'existence' means.

You seem pretty set in your opinion of what philosophy is, is that not correct?

From my standpoint, you are a brilliant person who is knowledgeable on an extraordinary number of subjects but your grasp of what philosophy is does not seem to jive with mine.

I'm weighing the idea of sometime in the next week or so starting a thread on the nature of philosophy.

 

[Polymath257]

You seem pretty set in your opinion of what philosophy is and thus incapable of learning much about it that you don't already "know", is that not correct?

No, actually. I read a fair amount of philosophy. I enjoy reading it. But I have found that it is pretty useless in actual understanding. In that regard, it is something akin to science fiction. Fun to read, but I don't expect to find deep truths in it.

From my standpoint, you are a brilliant person who is knowledgeable on an extraordinary number of subjects but your grasp of what philosophy is is below remedial. That's typical for an American -- and this time, I am not joking. American culture is anything but "philosophically sophisticated".

Well, I start with an almost complete rejection of Aristotelianism. In particular, almost all of his metaphysics has been shown in practice to be wrong. Plato, in many ways, is even worse. His mysticism seems to be a grand mistake that we are still trying to get away from. I much prefer Hume to Hegel. Kant is amusing, but his division of analytic and synthetic seems to be off to me. In particular, a prior synthetic knowledge seems, to me, to be non-sense. I like Russell, mostly because of what he did in math, but he seems like a hack compared to the others.

I think ethical philosophy to be more useful in many cases than metaphysics, for example. Rawl's ideas on structuring society seem to be good, although putting them into practice is another question.

I'm weighing the idea of sometime in the next week or so starting a thread on the nature of philosophy.

Sounds like fun!

 

[Vouthon]

But it should be pointed out that, contrary to your friend's claim, the original exponents of empiricism were religious people thinking they were investigating God's plan for the universe by considering how His work functions.

Very true.

One of the greatest deficiencies of classical, Greco-Roman thought (for all its sophistication and profundity) was that they really lacked empiricism and any comprehension of the need for making testable predictions. Historically, Christianity was instrumental in shaping the intellectual environment from which the sciences sprang - even though this scholarly recognition is at odds with the popular perception.

In contrast to his mentor Plato (who distrusted sense-perception so much that he conceived of truth as being in the realm of 'ideas' (Platonic Forms) and took basically a solipsistic view of physical reality), Aristotle did base his philosophy on observations of the natural order. It was for this reason that his philosophy (empirically wrong on so many points ranging from geocentrism to unmoved movers, though it actually was) appealed so much to medieval Muslims and Christians, such that he became "the Master" - the pre-eminent philosopher.

But Aristotle got so many things disastrously wrong (and thereby held back the advancement of 'scientific' knowledge for centuries, given the authority in which he was held by so many people ranging from the pagan Hero of Alexandria in the first century A.D. to Avicenna and St. Thomas Aquinas in the middle ages) because he had relied on passive observation of natural phenomena.

So it really wasn't any better than Platonism. The purpose of Ancient Greek Aristotelian "philosophy" was above all to explain the natural world in ways that correlated with theories, detached from experiment. It was not experimental, as all competent scholars of antiquity recognize: that is, motivated to understand the natural order on its own terms.

It really hampered their ability to 'progress' towards something approaching our modern scientific way of understanding the cosmos.

And the reason was very much rooted in their cultures.

As the Israeli physicist and philosopher of science Max Jammer explained in a 1997 study:

Foundations Of Quantum Mechanics In The Light Of New Technology: Selected Papers From The Proceedings Of The First Through Fourth International Symposia On Foundations Of Quantum Mechanics

Greek science was not experimental science. During the twelve centuries, from Thales to Philoponus, virtually no serious experiment had been performed. In fact, the very idea of an experiment was unacceptable to the Greek mind and this for three major reasons:

(1) The Greek denial of the comprehensibility of change. For the Greek mind, movement and change could never become a subject of scientific study. For only the stationary, the geometrical, which alone can be grasped in terms of the tenseless logic of fixed and unambiguous concepts was intelligible for the Greek mind...This attitude explains why they never developed a theory of dynamics...

Since the idea of an experiment implies the possibility of varying initial conditions and of observing their effect on the final result, the Greek mind, confined as it was to static forms, was not susceptible to the idea of planned and controlled experimentation

(2) The world of nature, according to Greek metaphysics was a world alive and divine...Any interference with the course of nature was for the Greek an act of violence...The performance of an experiment performed under artificial or unnatural conditions could consequently never increase knowledge of nature.

(3) The Greeks did not have a distinct notion of initial or boundary conditions​

It seems incongruous, even unbelievable, for many moderns to appreciate that apparently every single ancient natural philosopher - to a man - concurred (unambiguously and uncritically) with Aristotle that heavy objects fall faster than light ones. No one questioned it. Now, this is a fundamental error that could have easily been proven wrong with the simplest of experiments - so simple, that it astonishing no one thought of doing so before the Christian era.

In his Mechanics, for instance, Hero of Alexandria (10 AD – c. 70 AD) who was an important Roman era mathematician and engineer, states on the authority of Aristotle that heavy objects fall faster than light ones . Yet Hero did not subject this 'theory' to testability and nor did it occur to of his pagan, pre-Christian contemporaries to do so either.

It was not until the Christian worldview started to loosen stringent attachment to the ideas of Aristotle, that a Christian philosopher named John Philoponus (490–570) was in a position to actually perform one of the earliest recorded experiments to support his theories (which were critical of Aristotle courtesy of a set of Christian presuppositions), by dropping a heavy and light ball in the sixth century AD.

Philoponus discovered that both balls fell at almost the same speed: the objects (regardless of their mass) experienced the same acceleration when in a state of free fall. He had uncovered the equivalence principle, one of the fundamental principles of modern physics: drop two different weights, and (ignoring wind resistance) they will hit the ground at the same time.

This experiment demonstrated that the Aristotelians were wrong and showed that, to truly understand the laws of nature, empirical investigation was essential.

Philoponus was understandably scathing about Aristotle and his pagan rapporteur Simplicius (who had been defending Aristotelian theory in debate with him):

"...But this man [Aristotle] is completely erroneous, and our view may be completely corroborated by actual observation more effectively than by any sort of verbal argument. For if you let fall from the same height two weights, one many times heavier than the other you will see that the ratio of the times required for the motion does not depend [solely] on the weights, but that the difference in time is very small. ..."

— John Philoponus' refutation of the Aristotelian claim that the elapsed time for a falling body is inversely proportional to its weight​

But why did the Christian Philiponus subject his theories to empirical tests whereas the great thinker Aristotle did not?

The answer was theological:

John Philoponus - Wikipedia

Around 550 he wrote a theological work On the Creation of the World as a commentary on the Bible’s story of creation using the insights of Greek philosophers and Basil the Great. In this work he transfers his theory of impetus to the motion of the planets, whereas Aristotle had proposed different explanations for the motion of heavenly bodies and for earthly projectiles. Thus Philoponus' theological work is recognized in the history of science as the first attempt at a unified theory of dynamics.

He introduced a new period of scientific thought based heavily on three premises: (1) The universe is a product of one single God, (2) the heavens and the earth have the same physical properties, (3) and the stars are not divine.[7]

With these principles Philoponus went after his pagan rival, Simplicius of Cilicia, by questioning Aristotle's' view of dynamics and cosmology.

He also held that God created all matter with its physical properties and with natural laws that would allow matter to progress from a state of chaos to an organized state forming the present universe.[7] What remains of his writings indicate that he used the same didactic methods of reasoning that modern science uses and that he performed genuine experiments.[7]
​

This provenance - the unfortunate fact that our modern scientific way of thinking was completely accidental and culturally contigent rather than emerging as the inevitable consequence of some teleological outcome of "reason" itself - is understandably disturbing, which is why I think many people feel more comfortable believing in the cosy enlightenment idea of 'intrinsic progress'.

But if an apocalyptic Jew preaching the kingdom of God hadn't died on a Roman cross and been subsequently deified by his followers, it is likely the intellectual seedbed for the scientific revolution wouldn't have existed.

And that's scary, even to me, because its preferable to believe in inevitability as opposed to contingency. But the discovery was in a large part accidental, to the extent that it was contingent on a set of theological presuppositions critical of classical Greek presuppositions that wouldn't have been there had it not been for a series of accidents.

 

[Revoltingest]

It is pretty similar to how I know there is a chair in front of me without philosophizing about what 'existence' means.

For example, suppose there is a mathematical result that I don't feel like I understand. Which is better? To philosophize about it? Or to explore other aspects of the related mathematics to put it into context? For me, the answer is clearly the latter.

Metaphysics is fine for drinking with friends. But to think it actually helps at all with understanding is, as far as I can tell, a great mistake. Instead, it gives the illusion that we are thinking deeply when we are actually just rearranging our prejudices.

So, something is helpful with understanding if, when I do it or learn it, I understand better. It really is that simple.

The point is that not all thought is philosophizing, which has to do with generalities and overall methods. Such tend to be useless in practice. Instead, look and explore and think about what the evidence says.

Philosophy has become on par with religion, eh.

 

[Revoltingest]

No, actually. I read a fair amount of philosophy. I enjoy reading it. But I have found that it is pretty useless in actual understanding. In that regard, it is something akin to science fiction. Fun to read, but I don't expect to find deep truths in it.

I approach philosophy differently....
First, reading it is tedious & fruitless. But considering & discussing
it is interesting. What use is it? There are many things which are
important, but "nicht einmal falsch", eg, values, morals, goals, meaning.
Such things are explored, resolved, & decided upon....even though
they're not "true". It's useful, just not in the scientific sense of "useful".

 

[Vouthon]

I think ethical philosophy to be more useful in many cases than metaphysics, for example. Rawl's ideas on structuring society seem to be good, although putting them into practice is another question.

I think ethical philosophy is certainly useful.

One reason for that is the impossibility (the logical fallacy) of deriving "ought" from "is".

While our sense of morality is based in natural selection (resulting in our capacity for empathy, identification and co-operation with other minds), our sense of moral advancement cannot, and does not, arise from a study of nature because nature is profoundly amoral and purposeless. There is no "direction" in evolution, for example. It is not going "anywhere", or tending towards an end-goal (as poor Aristotle thought, with his teleological worldview and search for 'causes', 'goals' and unmoved movers in physics). You don't get a sense of ethical progression from studying random natural selection and survival of the fittest, because there is no teleology in mechanistic physical processes.

There is nothing in particle physics or biology which gives one a universal standard of ethical conduct. This idea is derived from religion and philosophy, it does not emerge as the logical and inevitable conclusion of any premises derived from natural, scientifically explicable processes.

Evolutionary biologist Professor Richard Dawkins, actually, has explained this well:


Richard Dawkins: 'We need an anti-Darwinian society'

“...Evolution by natural selection is the explanation for why we exist. It is not something to guide our lives in our own society. If we were to be guided by the evolution principle, then we would be living in a kind of ultra-Thatcherite, Reaganite society.

Study your Darwinism for two reasons, because it explains why you’re here, and the second reason is, study your Darwinism in order to learn what to avoid in setting up society. What we need is a truly anti-Darwinian society. Anti-Darwinian in the sense that we don’t wish to live in a society where the weakest go to the wall, where the strongest suppress the weak, and even kill the weak..."​

So I would say that philosophy is pretty essential to human society, because we aren't going to derive moral theories from science - this is really an area where human qualia - feelings, emotions, thoughts, ideas (the preserve of philosophy) - is critical.

 

[Polymath257]

Let's put it this way.

Name *one* metaphysical principle that has been relevant to the *formulation* of *any* scientific theory.

Empiricism, for example, doesn't work. That is simply how science goes about finding things out. It isn't relevant for any particular scientific theory. The closest I could come is some of Bohr's views on Buddhism.

No philosophical insights have been use helping to solve any scientific problem, as far as I know.

 

[atanu]

I don't understand your question. The values of things like momentum, spin, etc are not determined ahead of time. I'm not sure what significance is to the quark model.

Let's put it this way.

Name *one* metaphysical principle that has been relevant to the *formulation* of *any* scientific theory.

Empiricism, for example, doesn't work. That is simply how science goes about finding things out. It isn't relevant for any particular scientific theory. The closest I could come is some of Bohr's views on Buddhism.

No philosophical insights have been use helping to solve any scientific problem, as far as I know.

You have a very fragmented view of knowledge process.

 

[Polymath257]

You have a very fragmented view of knowledge process.

Could you expand on that claim?

 

[Polymath257]

Could you expand on that claim?

Let me put it this way. Dreams seem to be much more useful as a way of producing new scientific insights than, say, anything from metaphysics. I can point to numerous cases where the fundamental insight into a scientific question was produced in a dream (the prototypical example is Kekule's structure for benzene).

I have yet to see an example where metaphysics was relevant to solving a scientific problem.

 

[Vouthon]

Let's put it this way.

Name *one* metaphysical principle that has been relevant to the *formulation* of *any* scientific theory.

I'll have a crack. Not 'metaphysical' but philosophical/speculative.

Denying the utility of philosophy, is an act of doing philosophy. In writing something like: “philosophy is useless to physics,” one is not doing physics. One is rather making a critical reflection on the best way to develop the scientific endeavour. The issue is the methodology of science: a central focus in the philosophy of science is to ask how science is done and how it could be done to be more effective. Every good scientist must reflect on his or her own methodology.

Scientific theories "live or die based on internal consistency and, one hopes, eventual laboratory testing", to quote one prominent cosmologist George Ellis. The internal consistency part is helped by philosophy. Corpenican theory didn't start purely from new data (empirical test) but rather from, as one physicist writes: "an insightful analysis of successful well-established theories: Ptolemaic astronomy" and the same can be said for "Newtonian gravity and special relativity. The contradictions and unexplained coincidences they found in these would open the way to a new conceptualization."

The theoretical physicist Professor Carlo Rovelli argues that,

Philosophy provides methods leading to novel perspectives and critical thinking. Philosophers have tools and skills that physics needs, but do not belong to the physicists training: conceptual analysis, attention to ambiguity, accuracy of expression, the ability to detect gaps in standard arguments, to devise radically new perspectives, to spot conceptual weak points, and to seek out alternative conceptual explanations. Nobody puts this better than Einstein himself: “A knowledge of the historic and philosophical background gives that kind of independence from prejudices of his generation from which most scientists are suffering. This independence created by philosophical insight is—in my opinion—the mark of distinction between a mere artisan or specialist and a real seeker after truth.”​

So here's my attempt at evidencing that:


1. Heisenberg’s intuition:


https://phys.org/news/2013-10-physicists-heisenberg-intuition.html

An international team of scientists has provided proof of a key feature of quantum physics – Heisenberg's error-disturbance relation - more than 80 years after it was first suggested.

One of the basic concepts in the world of quantum mechanics is that it is impossible to observe physical objects without affecting them in a significant way; there can be no measurement without disturbance.

In a paper in 1927, Werner Heisenberg, one of the architects of the fundamental theories of modern physics, claimed that this fact could be expressed as an uncertainty relation, describing a reciprocal relation between the accuracy in position and the disturbance in momentum. However, he did not supply any evidence for the theory which was largely based on intuition.

Now Professor Paul Busch of the University of York, UK, Professor Pekka Lahti of the University of Turku, Finland and Professor Reinhard Werner of Leibniz Universität Hannover, Germany have finally provided a precise formulation and proof of the error-disturbance relation in an article published today in the journal Physical Review Letters.
​

The science of quantum mechanics springs from Heisenberg’s intuition (an utterly untested 'speculation'), grounded in the strongly positivist philosophical environment in which he found himself, which upheld the idea that, "one gets knowledge by restricting oneself to what is observable".

Even Einstein stated that he was indebt to the philosophical writings of Mach and Poincaré. The philosophical influences on the conception of general relativity were even more watertight than that. Once again, he was explicit in claiming his indebtedness to the philosophical arguments in Leibniz, Berkeley and Mach. Einstein claimed that even Schopenhauer had had a pervasive influence on his theory of general relativity.


2. Occam's razor (which demands that among two theories that achieve the same thing, you pick the one that’s simpler)

The theoretical physicist Sabine Hossenfelder of the Frankfurt Institute writes:

The purpose of science is to explain observations. In theoretical physics, we use mathematics for that. Our theories need a set of assumptions plus a way to identify math objects with observables. But none of the assumptions should be unnecessary, a criterion known as Ockham's razor (named after the 13th century theologian and philosopher William of Ockham). Ockham's razor is extremely important — as without it you could literally add invisible gods and angels to any scientific theory.​

This was a philosophical theory pioneered by a Catholic Dominican monk that has proved very fruitful to scientific enquiry.

3. Falsifiability (arguably)

(continued.................)

 

[Vouthon]

@Sunstone I think this is an interesting debate that you and @Polymath257 are having. Here's where I fall down. I sympathise with both of you, agreeing with Polymath about the essential pointlessness (in terms of trying to understand the world scientifically) of speculation unmoored from testable predictions. On the other hand, I think he perhaps makes the point a little too fiercely and thus neglects the essential contribution that philosophy can, and has definitely made, to science.

Your debate is actually rather timely, as the field of high-energy particle physics has been bedevilled for a number of decades now by a set of popular theories - such as 'super-string theory', supersymmetry and the eternal inflation 'multiverse' model that posits multiple universes with different local laws of physics, grand unification theories - that are mathematically 'beautiful' and elegant and philosophically compelling (actually, quite "sexy" to the extent that it would be fun if they were an accurate description of reality) but which either make no testable predictions at all in over 40 years or are actually beyond the ken of scientific knowledge completely (as in the case of the multiverse, given that the particle horizon sets a limit on what we can ever hope to 'see' through telescopes and the posited 'universes' would thus be causally disconnected, meaning we cannot even discern testable consequences of this theory).

In the foundations of physics, it has become accepted practice to prefer hypotheses that are aesthetically pleasing. But most of their, admittedly, beautiful ideas are difficult or impossible to test. And whenever an experiment comes back empty-handed, these physicists simply amend their theories to accommodate the null results - and the fruitless cycle starts all over again, no lesson learned.

There is thus a movement among some theoretical physicists to downplay the need for testability, because high-energy physics has hit a point where we are really struggling to find ways (and indeed the money) to smash particles together at ever higher-energies, after the LHC (Large Hadron Collider) failed to discover any new or exotic physics (other than the Higgs Boson) as 'theorised' for decades by many theoretical physicists as the solutions that would provide the most 'elegant' answers to the holes and inconsistencies we are left with in the standard-model.

An example of the danger this line of thought can pose to the scientific enterprise is highlighted by the cosmologist, and New York Times best-selling writer, Professor Sean Carroll:


Edge.org

2014 : WHAT SCIENTIFIC IDEA IS READY FOR RETIREMENT?

Sean Carroll

Theoretical Physicist, Caltech; Author, The Big Picture

Falsifiability


"...Modern physics stretches into realms far removed from everyday experience, and sometimes the connection to experiment becomes tenuous at best. String theory and other approaches to quantum gravity involve phenomena that are likely to manifest themselves only at energies enormously higher than anything we have access to here on Earth. The cosmological multiverse and the many-worlds interpretation of quantum mechanics posit other realms that are impossible for us to access directly. Some scientists, leaning on Popper, have suggested that these theories are non-scientific because they are not falsifiable.

The truth is the opposite. Whether or not we can observe them directly, the entities involved in these theories are either real or they are not. Refusing to contemplate their possible existence on the grounds of some a priori principle, even though they might play a crucial role in how the world works, is as non-scientific as it gets."​

Carroll calls this "Non-empirical confirmation".

Here’s his 2nd paragraph above with only a few point modifications, to illustrate how a Theist might argue using similar logic to Professor Carroll:

“Some scientists, leaning on Popper, have suggested that these theories [about a Theistic Fine-Tuning God] are non-scientific because they are not falsifiable.

The truth is the opposite. Whether or not we can observe Him directly, the Creator involved in this theory is either real or He is not. Refusing to contemplate His possible existence on the grounds of some a priori principle, even though He might play a crucial role in how the world works, is as non-scientific as it gets.

It's the "empirical" criterion that requires some care. At face value it might be mistaken for "makes falsifiable predictions." But in the real world, the interplay between theory and experiment isn't so cut and dried. A scientific theory is ultimately judged by its ability to account for the data—but the steps along the way to that accounting can be quite indirect.

The Creator might be inaccessible to us, but He is part of the theory that cannot be avoided”​

I believe, contrary to Professor Carroll, that rigorous science should involve falsifiable hypotheses—ones that can be confirmed or disproved by data and must be subjected to empirical test and be capable of making testable predictions.

This is - quite simply - Aristotelianism Redux. Not in terms of the teleology but in terms of the untestable metaphysics. I think we seriously have to ask if we are returning to the, "How many angels can dance on the head of a pin?" kind of scholastic-type thought, which was absolutely stepped in Aristotelian 'theoretics'.

That is the reason why Professor George Ellis, a greatly respected cosmologist and mathematician, has long been a strident opponent of the multiverse and string theory being touted as 'science', for instance in this peer-reviewed article from 2008:



Opposing the multiverse | Astronomy & Geophysics | Oxford Academic

Opposing the multiverse

George Ellis


Astronomy & Geophysics, Volume 49, Issue 2, 1 April 2008


The very nature of the scientific enterprise is at stake in the multiverse debate. Its advocates propose weakening the nature of scientific proof in order to claim that the multiverse hypothesis provides a scientific explanation. This is a dangerous tactic. Two central scientific virtues are testability and explanatory power. In the cosmological context, these are often in conflict with each other and there has been an increasing tendency in theoretical physics and cosmology to say it does not matter whether a proposal is testable: if it fits into our other theories in a convincing way, with great explanatory power, then testing is superfluous. The extreme case is the multiverse proposal, where no direct observational test of the hypothesis is possible...

Successful scientific theories make predictions that can be tested. The multiverse theory cannot make any testable predictions because it can explain anything at all.

Even though multiverse proposals are good empirically based philosophical proposals for the nature of what exists, they are not strictly within the domain of science. There is nothing wrong with empirically based philosophical explanation — indeed it is of great value provided it is labelled for what it is — but I suggest that cosmologists should be very careful not to make methodological proposals that erode the essential nature of science in their enthusiasm to support specific theories​

The inflationary multiverse is certainly plausible as a purely philosophical hypothesis, if one works under an assumption of naturalism. After all, it too has explanatory power and makes good sense of the data.

There is a push-back now in theoretical physics, against this kind of 'untestable hypothesizing'. As the physicist I mentioned earlier, Professor Carlo Rovelli writes preprint version here), and mainly in a single paragraph:

String theory is a living proof of the dangers of excessive reliance on non-empirical arguments. It raised great expectations thirty years ago, promising to compute all the parameters of the Standard Model from first principles, to derive from first principles its symmetry group SU(3)×SU(2)×U(1) and the existence of its three families of elementary particles, to predict the sign and the value of the cosmological constant, to predict novel observable physics, to understand the ultimate fate of black holes, and to offer a unique, well-founded unified theory of everything. Nothing of this has come true. String theorists, instead, have predicted a negative cosmological constant, deviations from Newton’s 1/r^2 law at sub-millimeters scale, black holes at the European Organization for Nuclear Research(CERN), low-energy super-symmetric particles, and more. All this was false. Still, Joe Polchinski, a prominent string theorist, writes [7] that he evaluates the Bayesian probability of string to be correct at 98.5% (!). This is clearly nonsense.​

And so, this is where I do agree with you @Polymath257 and I think Professor Sabine Hossenfelder gets it right when she says:

I think it’s time we take a lesson from the history of science. Beauty does not have a good track record as a guide for theory-development. Many beautiful hypotheses were just wrong, like Johannes Kepler’s idea that planetary orbits are stacked in regular polyhedrons known as ‘Platonic solids’, or that atoms are knots in an invisible aether, or that the Universe is in a ‘steady state’ rather than undergoing expansion.​

 

[Polymath257]

@Sunstone I think this is an interesting debate that you and @Polymath257 are having. Here's where I fall down. I sympathise with both of you, agreeing with Polymath about the essential pointlessness (in terms of trying to understand the world scientifically) of speculation unmoored from testable predictions. On the other hand, I think he perhaps makes the point a little too fiercely and thus neglects the essential contribution that philosophy can, and has definitely made, to science.

Your debate is actually rather timely, as the field of high-energy particle physics has been bedevilled for a number of decades now by a set of popular theories - such as 'super-string theory', supersymmetry and the eternal inflation 'multiverse' model that posits multiple universes with different local laws of physics, grand unification theories - that are mathematically 'beautiful' and elegant and philosophically compelling (actually, quite "sexy" to the extent that it would be fun if they were an accurate description of reality) but which either make no testable predictions at all in over 40 years or are actually beyond the ken of scientific knowledge completely (as in the case of the multiverse, given that the particle horizon sets a limit on what we can ever hope to 'see' through telescopes and the posited 'universes' would thus be causally disconnected, meaning we cannot even discern testable consequences of this theory).

In the foundations of physics, it has become accepted practice to prefer hypotheses that are aesthetically pleasing. But most of their, admittedly, beautiful ideas are difficult or impossible to test. And whenever an experiment comes back empty-handed, these physicists simply amend their theories to accommodate the null results - and the fruitless cycle starts all over again, no lesson learned.

There is thus a movement among some theoretical physicists to downplay the need for testability, because high-energy physics has hit a point where we are really struggling to find ways (and indeed the money) to smash particles together at ever higher-energies, after the LHC (Large Hadron Collider) failed to discover any new or exotic physics (other than the Higgs Boson) as 'theorised' for decades by many theoretical physicists as the solutions that would provide the most 'elegant' answers to the holes and inconsistencies we are left with in the standard-model.

An example of the danger this line of thought can pose to the scientific enterprise is highlighted by the cosmologist, and New York Times best-selling writer, Professor Sean Carroll:


Edge.org

2014 : WHAT SCIENTIFIC IDEA IS READY FOR RETIREMENT?

Sean Carroll

Theoretical Physicist, Caltech; Author, The Big Picture

Falsifiability


"...Modern physics stretches into realms far removed from everyday experience, and sometimes the connection to experiment becomes tenuous at best. String theory and other approaches to quantum gravity involve phenomena that are likely to manifest themselves only at energies enormously higher than anything we have access to here on Earth. The cosmological multiverse and the many-worlds interpretation of quantum mechanics posit other realms that are impossible for us to access directly. Some scientists, leaning on Popper, have suggested that these theories are non-scientific because they are not falsifiable.

The truth is the opposite. Whether or not we can observe them directly, the entities involved in these theories are either real or they are not. Refusing to contemplate their possible existence on the grounds of some a priori principle, even though they might play a crucial role in how the world works, is as non-scientific as it gets."​

Carroll calls this "Non-empirical confirmation".

Here’s his 2nd paragraph above with only a few point modifications, to illustrate how a Theist might argue using similar logic to Professor Carroll:

“Some scientists, leaning on Popper, have suggested that these theories [about a Theistic Fine-Tuning God] are non-scientific because they are not falsifiable.

The truth is the opposite. Whether or not we can observe Him directly, the Creator involved in this theory is either real or He is not. Refusing to contemplate His possible existence on the grounds of some a priori principle, even though He might play a crucial role in how the world works, is as non-scientific as it gets.

It's the "empirical" criterion that requires some care. At face value it might be mistaken for "makes falsifiable predictions." But in the real world, the interplay between theory and experiment isn't so cut and dried. A scientific theory is ultimately judged by its ability to account for the data—but the steps along the way to that accounting can be quite indirect.

The Creator might be inaccessible to us, but He is part of the theory that cannot be avoided”​

I believe, contrary to Professor Carroll, that rigorous science should involve falsifiable hypotheses—ones that can be confirmed or disproved by data and must be subjected to empirical test and be capable of making testable predictions.

This is - quite simply - Aristotelianism Redux. Not in terms of the teleology but in terms of the untestable metaphysics. I think we seriously have to ask if we are returning to the, "How many angels can dance on the head of a pin?" kind of scholastic-type thought, which was absolutely stepped in Aristotelian 'theoretics'.

That is the reason why Professor George Ellis, a greatly respected cosmologist and mathematician, has long been a strident opponent of the multiverse and string theory being touted as 'science', for instance in this peer-reviewed article from 2008:



Opposing the multiverse | Astronomy & Geophysics | Oxford Academic

Opposing the multiverse

George Ellis


Astronomy & Geophysics, Volume 49, Issue 2, 1 April 2008


The very nature of the scientific enterprise is at stake in the multiverse debate. Its advocates propose weakening the nature of scientific proof in order to claim that the multiverse hypothesis provides a scientific explanation. This is a dangerous tactic. Two central scientific virtues are testability and explanatory power. In the cosmological context, these are often in conflict with each other and there has been an increasing tendency in theoretical physics and cosmology to say it does not matter whether a proposal is testable: if it fits into our other theories in a convincing way, with great explanatory power, then testing is superfluous. The extreme case is the multiverse proposal, where no direct observational test of the hypothesis is possible...

Successful scientific theories make predictions that can be tested. The multiverse theory cannot make any testable predictions because it can explain anything at all.

Even though multiverse proposals are good empirically based philosophical proposals for the nature of what exists, they are not strictly within the domain of science. There is nothing wrong with empirically based philosophical explanation — indeed it is of great value provided it is labelled for what it is — but I suggest that cosmologists should be very careful not to make methodological proposals that erode the essential nature of science in their enthusiasm to support specific theories​

The inflationary multiverse is certainly plausible as a purely philosophical hypothesis, if one works under an assumption of naturalism. After all, it too has explanatory power and makes good sense of the data

There is a push-back now in theoretical physics, against this kind of 'untestable hypothesizing'. As the physicist I mentioned earlier, Professor Carlo Rovelli writes preprint version here), and mainly in a single paragraph:

String theory is a living proof of the dangers of excessive reliance on non-empirical arguments. It raised great expectations thirty years ago, promising to compute all the parameters of the Standard Model from first principles, to derive from first principles its symmetry group SU(3)×SU(2)×U(1) and the existence of its three families of elementary particles, to predict the sign and the value of the cosmological constant, to predict novel observable physics, to understand the ultimate fate of black holes, and to offer a unique, well-founded unified theory of everything. Nothing of this has come true. String theorists, instead, have predicted a negative cosmological constant, deviations from Newton’s 1/r^2 law at sub-millimeters scale, black holes at the European Organization for Nuclear Research(CERN), low-energy super-symmetric particles, and more. All this was false. Still, Joe Polchinski, a prominent string theorist, writes [7] that he evaluates the Bayesian probability of string to be correct at 98.5% (!). This is clearly nonsense.​

And so, this is where I do agree with you @Polymath257 and I think Professor Sabine Hossenfelder gets it right when she says:

I think it’s time we take a lesson from the history of science. Beauty does not have a good track record as a guide for theory-development. Many beautiful hypotheses were just wrong, like Johannes Kepler’s idea that planetary orbits are stacked in regular polyhedrons known as ‘Platonic solids’, or that atoms are knots in an invisible aether, or that the Universe is in a ‘steady state’ rather than undergoing expansion.​

While string theory has some very beautiful math, in its current incarnation I hesitate to call it science for the very reasons mentioned here. Beauty is just not a good criterion for evaluation of truth. The strength of science is *precisely* that it is empirical. When done right, it does not get too far from what is testable and thereby avoids the 'angels on pins' issues.

The underlying concept is that an idea that is compatible with everything actually explains nothing.

In regard to the multiverse models, there *are* examples that can be tested empirically (at least in theory) and I am willing to say those are scientific. Others are different ways of solving the mathematical problems (also called interpretations) and I don't give them a separate status from their testability.

For example, the Laplacian way of formulating classical mechanics is mathematically equivalent to Newtonian physics, but philosophically very different. But both are considered the *same theory* because they make the exact same testable predictions. I see the different interpretations of quantum mechanics to be in the same mold: ultimately, the differences are irrelevant: the testable predictions are *all* that is relevant.

 

[Vouthon]

In regard to the multiverse models, there *are* examples that can be tested empirically (at least in theory) and I am willing to say those are scientific. Others are different ways of solving the mathematical problems (also called interpretations) and I don't give them a separate status from their testability.

Really the only way I can think of them being tested in theory is the idea of "bubble collision" (in eternal inflation models). But to me, that's rather dog chasing the tail. Some such models predict observable effects in the CMB. Those are perfectly scientific and easy to evaluate, just they seem to be plain wrong (since we see no such thing). Other such models predict no observable effect, those are untestable.

But the really problematic "multiverse model" is the string theory landscape one, and that's the one I discussed above.

There is for instance the “many-worlds” multiverse stemming from one (among many competing) interpretations of Quantum Mechanics which results in parallel universes existing in different spacetimes from our own but with the exact same physics as ours. That multiverse is all about the wavefunction measurement problem.

In essence, it consists of the weird but theoretically possible idea that the universe splits into parallel worlds at every quantum measurement.

The other types of multiverses have nothing to do with Quantum Mechanics but rather arise from cosmic inflation and are known as “cosmological multiverse” models because they are thought up by cosmologists as opposed to quantum physicists.

These multiverses comprise of “bubbles” or rather causally disconnected bubbles within the one space-time - our space-time.

One form of this cosmological multiverse - the popular one in the public imagination - rests upon the unsubstantiated idea of a string landscape in M-Theory which makes it possible to conceive of higher dimensions and universes (or "vacua") with utterly different laws of local physics and constants. As Peter Woit notes about it: "The real problem is that you don’t have a theory: “M-theory” is a word but not an actual theory. The problem is not that it’s “hard” to figure out what the measure on the space of string vacua is, but that you don’t even know what the space is on which you’re looking for a measure. This is not a “hard” question, it’s simply a question for which you don’t have a theory which gives an answer.".

Carroll and a few other physicists are so wedded to this "beautiful idea" that they are happy to lower the standards of scientific enquiry and the criterion of testability to retain it in the absence of empirical testability. And the result is concerning.

The most basic kind of cosmological multiverse, however, is one which arises from a single inflation field and leads to the exact same physical constants in each of the causally disconnected “patches” of space. We call this a “Type 1” cosmological multiverse.

I don’t know of anyone who finds this notion in the least bit controversial – the consideration that there are likely regions beyond the particle horizon which we can’t observe but where the same underlying physics applies.

 

[Polymath257]

Really the only way I can think of them being tested in theory is the idea of "bubble collision" (in eternal inflation models). But to me, that's rather dog chasing the tail. Some such models predict observable effects in the CMB. Those are perfectly scientific and easy to evaluate, just they seem to be plain wrong (since we see no such thing). Other such models predict no observable effect, those are untestable.

Agreed. The ones that are testable have mostly been tested and shown wrong.

But the really problematic "multiverse model" is the string theory landscape one, and that's the one I discussed above.

There is for instance the “many-worlds” multiverse stemming from one (among many competing) interpretations of Quantum Mechanics which results in parallel universes existing in different spacetimes from our own but with the exact same physics as ours. That multiverse is all about the wavefunction measurement problem.

In essence, it consists of the weird but theoretically possible idea that the universe splits into parallel worlds at every quantum measurement.

Yep. And as far as I can see, they seem to be ways of playing with the math. I tend to put any two 'theories' that make the same testable predictions into the same equivalence class and simply call the whole a theory.

So, these variations, and other interpretations of QM are, as far as I can see, identical theories.

The other types of multiverses have nothing to do with Quantum Mechanics but rather arise from cosmic inflation and are known as “cosmological multiverse” models because they are thought up by cosmologists as opposed to quantum physicists.

These multiverses comprise of “bubbles” or rather causally disconnected bubbles within the one space-time - our space-time.

One form of this cosmological multiverse - the popular one in the public imagination - rests upon the unsubstantiated idea of a string landscape in M-Theory which makes it possible to conceive of higher dimensions and universes with utterly different laws of local physics and constants. As Peter Woit notes about it: "The real problem is that you don’t have a theory: “M-theory” is a word but not an actual theory. The problem is not that it’s “hard” to figure out what the measure on the space of string vacua is, but that you don’t even know what the space is on which you’re looking for a measure. This is not a “hard” question, it’s simply a question for which you don’t have a theory which gives an answer.".

Exactly. Not even a hypothesis, really.

Carroll and a few other physicists are so wedded to this "beautiful idea" that they are happy to lower the standards of scientific enquiry and the criterion of testability to retain it in the absence of empirical testability. And the result is concerning.

Agreed. And, the way I would describe this is that Carroll is doing philosophy at this point and not science.

The most basic kind of cosmological multiverse, however, is one which arises from a single inflation field and leads to the exact same physical constants in each of the causally disconnected “patches” of space. We call this a “Type 1” cosmological multiverse.

I don’t know of anyone who finds this notion in the least bit controversial – the consideration that there are likely regions of the universe beyond the particle horizon which we can’t observe but where the same underlying physics applies.

Right. The difficulty is when you then ask whether space is infinite, for example. If the curvature is very close to zero, but so close that we cannot distinguish it from zero, we might have a Type 1 situation where the particle horizon is a *very* small part of space, but where space is still finite in extent. Also, mathematically it is possible to have a curvature zero space, or even a positive curvature space be finite (a possibility many physicists don't seem to be aware of).

 

[Polymath257]

Another aspect of this conversation that I would like to bring out.

Philosophy is best when it is asking probing questions. It is worst when it proposes answers.

Pushing us to think about how we define things, to consider alternative ideas, and to probe how we think we know what we think we know *is* a useful thing. It may get us to think about issues we would have never considered before. And that is a very good thing.

On the other hand, philosophy tends to go bad when it thinks it has answers. From Plato, to Aristotle, to Kant and Hegel, the questions raised tend to be good ones. The answers, on the other hand, tend to be biased by their time period.

My favorite example is Kant. He considered Euclidean geometry to be synthetic a priori knowledge. If he has merely questioned that assumption, he may have been one of the founders of non-Euclidean geometry. He may have been able to ponder the possibilities of curved space and time well before Einstein. But, because he was mired in the biases of his time, he failed to do that. Of course, it would have also have meant rethinking the concept of synthetic a priori knowledge.

Instead of asking if there is synthetic a priori knowledge, he made a claim that such exists and thereby fell victim to his time.

Even today, it is clear that most philosophers (maybe all) have failed to learn the basics of quantum mechanics. Given that it is almost a century old, that seems to be a horrible mistake. And the consequences for classical metaphysics are profound. The very concepts that have been assumed to be 'the only way things could be' have been shown to be wrong.

This carries into the almost universal acceptance among philosophers of Bohmian mechanics even though essentially NO working physicist uses that system. The discrepancy is telling, in my mind. Philosophers have failed to learn the lessons of physics over the past century, thereby making themselves less and less relevant to the real, fascinating, discussions about the physical world. Realism trumps locality in their minds even though in physics it is precisely the reverse.