Quantum Non-Linearity: People in (Epistemic) Glass Houses…..

This post by “News” (= Denise O’Leary) on Uncommon Descent raises questions about the nature of scientific epistemology. The redoubtable Ms. O’Leary starts with some quotes and then comments on them. Below I reproduce the article along with my own interleaved comments.

Breaking: Article in Nature defends integrity of physics against multiverse, string theory

December 18, 2014

Posted by News under Cosmology, Intelligent Design, News

7 Comments

“Scientific method: Defend the integrity of physics” by George Ellis and Joe Silk,” Nature, open access:

This year, debates in physics circles took a worrying turn. Faced with difficulties in applying fundamental theories to the observed Universe, some researchers called for a change in how theoretical physics is done. They began to argue — explicitly — that if a theory is sufficiently elegant and explanatory, it need not be tested experimentally, breaking with centuries of philosophical tradition of defining scientific knowledge as empirical. We disagree. As the philosopher of science Karl Popper argued: a theory must be falsifiable to be scientific.

My Comment: This kind of epistemic manoeuvring is, to my mind a) forced on us in sciences that investigate complex “high level” and/or less than accessible objects such as we find in sociology or world view synthesis b) not as worrying as the authors of this quote think as it is necessarily widespread and may be little different for physics at the high end. It would be very nice if all theories could be predictively tested against experiential protocols, but the fact is testing at will is not always an option in the face of epistemic intractability; we may have to fall back on trying to assess just how well the theory makes post-facto sense of the data samples to hand. Moreover, "falsifiability" provides no sharply defined criterion for demarcating "good" or "proper" science, because no theory is absolutely falsifiable; we can always, with a bit of imagination, appeal to hidden adjustable variables in order to “explain” away anomalies, although this kind of special pleading, if used in quantity to prop up a failing theory, can start to look a little contrived; multiplication of variables, if reality is really that complex, considerably reduces the chance of us hitting the right combination of variables. It is no surprise then that everybody hopes that Occam’s heuristic is right, a heuristic that works on the presupposition that the world is rational and simple, with few variables and therefore with less opportunity to get things wrong!

Earlier this year, championing the multiverse and the many-worlds hypothesis, Carroll dismissed Popper’s falsifiability criterion as a “blunt instrument” (see go.nature.com/nuj39z). He offered two other requirements: a scientific theory should be “definite” and “empirical”. By definite, Carroll means that the theory says “something clear and unambiguous about how reality functions”. By empirical, he agrees with the customary definition that a theory should be judged a success or failure by its ability to explain the data.

He argues that inaccessible domains can have a “dramatic effect” in our cosmic back-yard, explaining why the cosmological constant is so small in the part we see. But in multiverse theory, that explanation could be given no matter what astronomers observe. All possible combinations of cosmological parameters would exist somewhere, and the theory has many variables that can be tweaked. Other theories, such as unimodular gravity, a modified version of Einstein’s general theory of relativity, can also explain why the cosmological constant is not huge.

Some people have devised forms of multiverse theory that are susceptible to tests: physicist Leonard Susskind’s version can be falsified if negative spatial curvature of the Universe is ever demonstrated. But such a finding would prove nothing about the many other versions. Fundamentally, the multiverse explanation relies on string theory, which is as yet unverified, and on speculative mechanisms for realizing different physics in different sister universes. It is not, in our opinion, robust, let alone testable.

My Comment: Carroll is implicitly admitting that some of these exotic physical theories are not easily testable at will, although they do in his opinion make sense of accepted “empirical” evidence. He therefore advocates relaxing the requirement that a theory should make testable predictions, but demands that a theory at least make unambiguous empirical post-dictions about our cosmos. As I have said many times in this blog some ontologies are a lot less epistemically tractable than others, (That would certainly apply to multiverse ideas for example) and this entails these ontologies being less amenable to data sampling. I have no particular objection to Carroll’s wanting to relax the epistemic standard so long as he acknowledges the risks and the loss of empirical authority. Moreover, if Carroll has at last realised that some ontologies are less empirically responsive than others he ought to also realise that he has stumbled upon a sliding scale that can be pushed even further. Viz: Some theoretical objects, particularly in the social and historical sciences, don’t have an unambiguous connection with observational protocols. but make probabilistic post dictions. So, on balance I’ve no complaints about Carroll’s epistemic procedure provided he doesn’t start pushing it as part of the authoritative status quo that gives him a pretext to kick dissenters into line.

But the redoubtable Denise is less sympathetic:

No wonder some would like to abandon testability for elegance, and reality for fairy tales.

Unfortunately, the plea ends on a somewhat tinny note,

“The imprimatur of science should be awarded only to a theory that is testable. Only then can we defend science from attack.”

Guys, listen (yes, you George Ellis and you Joe Silk, it is you we are looking at): The problem really isn’t attacks from outside. Quit fooling yourselves.

The problem is entirely within. If physicists want to join the many and various advocates of self-expression who do not depend on rigorous examination of evidence to validate their assertions, that is a choice physicists make.

No one forces that choice on physicists. But they are free to make it.

It sounds as though some of your colleagues have been making just such choices, and defending their choices by asking for exemption from traditional standards. It’s your profession’s call to determine whether their wishes/demands can be accommodated simply to prop up whatever rickety theoretical structures they have built.

But if your profession does choose to accommodate, two things:

1. Physics becomes just another player in a culture war, with no more genuinely respectable claims for attention than the demands we hear daily from grievance warriors that their version of events be accepted without cavil as Truth. You could find yourselves currying favour with politicians, as an identity group, for your version of nature versus that of magical thinking. Is that really what you want?

2. If so, just remember, no one did that to you. You did it to yourselves.

See also: The bill arrives for cosmology’s free lunch

My Comment: …but she’s probably right in her drift: The kind of “high level” barely accessible ontologies Carroll is proposing lose something of their empirical authority and have more the flavour of a world view synthesis. They therefore should not be pushed as logically obliging “Truth” or “fact”; that’s the sort of thing fundamentalists do. Conversely, I’m sure Denise realises that her ID community also have a science that is not good at making unambiguous predictions, and is better regarded as a post-facto quasi-archaeological sense making proposal. So, all in all there are lessons in mutual understanding here for both Denise O’Leary and Sean Carroll.

But when it comes to foisting on people world views that masquerade as “Truth”, I avoid communities and cultures that are predatory and use "moral" duress, group pressure and worse to persuade: Crowds of people with a highly uniform world view have always given me the creeps.