## Saturday, October 03, 2015 ... //

### Metaphysics is needed, should face competition, too

Days ago, I discussed Lawrence Krauss' tirade slinging mud at the concept of a theory of everything.

I have also mentioned another text in the same issue of the e-magazine, Life Is a Braid In Spacetime, by Mad Max Tegmark, but I think that it's even more vacuous than his well-known texts about the Mathematical Universe. His text is equivalent to: There is a spacetime. Something is mathematical about it. Sometimes it's the future, sometimes it's the past. If one is a bird, he can look from a bird's perspective. If he is a frog, he may have a frog's perspective.

If it won't be raining, we won't get soaked. (The previous sentence is from a popular Czech children's song that was the template for Smetana's The Moldau ;-) and that I began to use as a symbol of tautologies and "easy prophesies".)

Life is complicated. World lines of living things are complex, too. Yup but where's the beef, Max? Thed text is like Gigi's Puzzle in the Fio Bank's TV commercial: Which of us is me: he... or me...? – He [while each solver points at a different man]. – The solver #1 is a moron moron, the solver #2 is an imbecile moron.

Why Science Needs Metaphysics
by Roger Trigg, a retired English philosophy professor. One must be careful about propositions of this sort but the title is mostly correct.

Trigg argues that we can't live without metaphysics because certain questions, such as the mystery that Einstein described by his quote "the most incomprehensible thing about the world is that it is comprehensible", can't be addressed by physics itself. They seem to go "beyond" physics. The very applicability of reason as a tool to study Nature is a mysterious and potentially controversial issue.

Even more importantly, the philosopher correctly points out that most of the people who angrily insist on the elimination of metaphysics are usually using metaphysics as well, just a different one. I totally agree with that. This issue has an analogy in politics. Some people say that they prefer "apolitical" or "non-ideological" politics but if you look what they actually promote, you see that – as Czech ex-president Klaus loved to emphasize – they are tightly connected (perhaps more tightly than others) with another ideology, mostly a left-wing one.

There are some commenters beneath Trigg's essay who completely disagree with the philosopher's ideas. An Ape American named Hominid (his avatar seems to confirm his proclaimed race or species) says that all of metaphysics is a superstition just like gods, goblins, and Godzillas. It's nonsense, there is no evidence for anything metaphysical, and we should and must live without that.

This attitude is clearly a manifestation of something we may call naive realism. People like that believe that there exists some objective world (as envisioned in classical physics) and we may directly observe it and deduce all important truths about it.

But this view is obviously metaphysics as well and a very stupid one. The world seems to work in some way, have patterns and laws, and there is no direct way to deduce them. The search for the laws of physics is a very difficult inverse problem that requires creativity, intuition, and experience needed to make viable guesses about the possible form of the laws of physics. (And even the understanding of the laws found by others requires the understanding of increasingly abstract and deep mathematics.) These guesses are then competing with each other. The agreement with the observations and the explanatory power is what matters in this competitive struggle.

But the very character of the laws of physics may undergo profound, qualitative, conceptual revolutions. The transition from classical physics to quantum mechanics was arguably the most groundbreaking paradigm shift of all. But there have been many other paradigm shifts when it comes to the "general architecture or philosophy of the theories describing Nature", like the transition from mechanics to field theory, from the Galileo-Newtonian spacetime to the Einstein-Lorentzian relativistic one, or the curved one.

And there have been many conceptual steps totally revising the strategy or primary concepts we use to understand phenomena. Statistical physics works with constructive microscopic theories of matter; but thermodynamics works with general principles constraining the macroscopic evolution of systems. Like thermodynamics, relativity may be said to be a principle-based theory, Einstein liked to say. One starts with the axioms – postulates – that seem viable and tries to deduce as many general consequences as he can. In thermodynamics, the non-existence of the perpetual motion machines were these postulates. The constancy of the speed of light and the principle of relativity play the same role in relativity.

A nearly equivalent way to describe the paradigm shift in the case of relativity is that people learned how to place symmetry at the root of their reasoning. Some general patterns that we could have thought to be coincidental – and only work accidentally – are actually identified as principles that work exactly and universally and they allow us to deduce lots of things rather easily. And one may collect arbitrarily extensive and accurate evidence to back these principles and symmetries.

When the quantum mechanical postulates are applied to fields, one encounters divergences and faces lots of seemingly technical questions – that may be, due to the people's emotional reactions, said to be psychological or metaphysical – about the acceptability of the infinities, their meaning, legality of their subtractions, and so on. These methods used to be considered illegitimate – even by giants such as Dirac – but the continuing progress made it clear that the opposition was really irrational. This was a change of the metaphysics, too. The explanation of the legality of the renormalization procedure by the concept of the effective field theory – and the methods of the renormalization group – was yet another "metaphysical" advance.

The naive realists who say things like "metaphysics shouldn't exist at all" are clearly unfamiliar with all these things that actually form the skeleton of the history of physics and its contemporary portrait of the Universe. These advances – which changed the very basic opinions of physicists about the "reality" – have occurred and they have been important. They have arguably been the most important findings in physics. I would even say that by definition, the deepest breakthroughs in physics are those that affect the basic metaphysical aspects of thinking.

If some of you prefer as ambitious advances in physics as your humble correspondent, you are surely focusing on ideas that have the potential to revolutionize metaphysics. In some sense, everything else are just technical details.

The Homonid and his fellow naive realists are imagining that "metaphysics" is unavoidably something like a "bearded god on the cloud". Sometimes they even explicitly write silly things like that. It's easier to fight a straw man than to fight against the essential theories of science (and in fact, also than to fight against an actual bearded god on the cloud). But "metaphysics" that is so vital for the modern physics is nothing of the sort. Metaphysics is the set of ideas and assumptions that are linking and mapping the logical thinking with the (hypothetical or real) world around us.

You may say that there is a world around us but it's not available to our senses and thoughts "directly". Our eyes only see a tiny interval of the electromagnetic spectrum; only distinguish the colors by three (instead of infinitely many) parameters, the red, green, and blue intensities; they have a lousy resolution; they can't see things that are too tiny or too far or too dim or behind other objects, and so on. ;-) Even when we see them, we see 2D projections of a sort and they may be distorted by lots of optical effects, illusions, or diffraction (wave phenomena of light). We may improve our eyes by telescopes and microscopes and radio telescopes and millions of other things. It helps but opens a whole new can of worms when it comes to basic questions that at least initially look metaphysical, what is real, what is not real, what you can trust, what is objective, and so on. Only when people understand the new theory and tools well, they may confidently reclassify the "metaphysical" questions as "physical" ones.

Quantum mechanics insists that you must be maximally careful about all these things. When you observe something, it doesn't mean that it was objectively there and every other honest person must have agreed with that. Instead, when you reliably observe something, it just becomes a reliable truth from your point of view. But the truth wasn't a truth before you observed it – the observation unavoidably affected the state of the observed system – and the observation is inevitably subjective in character, too. If you observe something, it's your internal feeling that you know the particular result. But others may only agree that you have a "sharp knowledge" if they make their own observation of you, or something like that.

All these initially counterintuitive properties of quantum mechanics may be said to be parts of metaphysics. It's metaphysics in the sense that the correct way of thinking inevitably goes beyond the very straitjacket that you could have previously demanded to define "all legitimate science". In classical physics, you were allowed to add fields, the metric tensor, curved spacetime, relativity of simultaneity, very complicated nonlinear and nonpolynomial interactions, tons of other degrees of freedom, and so on. Someone could have said that "this freedom, just like 640 kB, should be enough for everyone". But it's just not enough for Nature – and those who want to understand Her at the 20th or 21st century level. The results that led to quantum mechanics showed that despite all the apparent freedom, this straitjacket was far too constraining and the correct theory of the microscopic world simply cannot belong to this set of (classical) theories.

The quantum revolution – and other revolutions – forced us to change what was considered to be the defining limits of "physics" or "science", and that's why these revolutions required a breakthrough in metaphysics. You may describe the same idea in many ways but the content is true and important, anyway. The key lesson undoubtedly is that naive realism is absolutely inadequate for modern science. The people who believe naive realism often think that they're very scientific but for more than 100 years, this self-confidence of theirs has contradicted the new results in physics.

As Bohr once said, quantum mechanics – but even already classical statistical physics – doesn't want to address what the world "is" like, but what correct propositions about the world we can "say". So the focus is on propositions – in the sense of logic (or the probability calculus – because the ultimate verifiable answers we are calculating are not binary but real probabilities). This is a general principle that the naive realists and hardcore materialists typically entirely misunderstand. But modern physics just can't work without this realization.

One may also talk about controversial metaphysical concepts such as the multiverse – whose majority will be forever unobservable for us – or even the anthropic principle. Naive realists love to reject all these ideas immediately. They're metaphysics for them, not science. However, they commit one absolutely obvious logical fallacy at the beginning. In physics, it is the different "propositions" and "ideas" that are competing with each other, not the "objects" themselves.

So e.g. "the multiverse" isn't a competitor in physics. Instead, it is the statement "There exists the multiverse." As a naive realist, you may reject this statement. But when you reject the proposition "There exists the [at least one] multiverse", you are equivalently saying the negation of this statement, "The number of multiverses is zero." You know, the problem for the naive realist is that this (negated) proposition depends on the "multiverse" as well, so if talking about the multiverse were "unscientific", so would be all the things that the opponent of the multiverse says about the problem!

At the end, whether you like it or not, theories envisioning the multiverse are conceptually or metaphysically new but they are possible competitors among hypotheses trying to describe the observations. So we have to treat this hypothesis as impartially as other hypotheses that are building on different, perhaps "more traditional" kinds of metaphysics. We must impartially look for evidence supporting or disfavoring the metaphysically new hypotheses as well as the metaphysically old-fashioned ones! If I oversimplify just a little bit, if you want to defeat the multiverse, you have to falsify it or find a more predictive or accurate theory that is also resisting falsification. In science, there's just no other way to kill a correctly constructed sentence linked to the observable phenomena.

You know, certain things may refuse to have a sharp scientific derivation. The particular outcomes in experiments explained by quantum mechanics almost certainly don't have a scientific explanation. Shapes of the continents are also mostly "random" (even the quantum randomness has surely affected them!) and some or all properties of the right compactification of string theory may be "random", too. You can't disprove these possibilities just by screaming "metaphysics". There's nothing wrong about "metaphysics". These questions are indeed deep enough to be called "metaphysical" but we still need to know the answers and screaming expletives or being an apologist for a Leeter Shmoit isn't a valid way to single out the right answer to anything.

Whatever seems viable and may lead to a theory or a framework that is capable of explaining a greater number of facts or patterns has to be considered as a valid competitor. It is the people who reject some competing hypotheses as "metaphysics" who are metaphysically prejudiced and who are doing science incorrectly – they are not doing science at all.

I should perhaps emphasize that the metaphysical prejudices and dogmas are one of the greatest enemies of the scientific method. You simply can't reject a possible hypothesis without a careful comparison of this hypothesis with the known facts – and with the competing hypotheses. This a priori rejection is what the Catholic Church was doing 500+ years ago. It doesn't matter whether you call the a priori rejected theories "heretical", "blasphemous", "politically incorrect", or "metaphysical". The root of the problem is always the same: you are trying to intimidate scientists and dishonestly suppress the evidence pointing to a certain direction that is inconvenient to you!

The metaphysically prejudiced people are the naive realists. But most of the professional philosophers or theologians or champions of churches and sects are metaphysically prejudiced as well, of course. So at the end, I must emphasize one thing. When I say that "metaphysics is ultimately needed in the physics research and the evolution of physics", it doesn't mean that "philosophers are those who should be the ultimate bosses and supervisors of physicists and scientists". I am not saying the latter thing at all. On the contrary!

The right metaphysics has to be found by the careful derivation of consequences and comparisons with the known facts about Nature – the usual job that is done by physicists or other scientists! Someone's being employed as a philosopher probably doesn't help him at all to find the right metaphysics for modern physics (maybe it hurts in average). But the fact that pure philosophers don't seem to be useful can't change anything about our observations that metaphysics – selected by physicists via physical arguments – is not only needed in physics but it sits at the heart of physics and at the core of all the big revolutions in physics.