Most people are of the opinion that scientific theories are theories that can be tested and which make predictions which can be confirmed or falsified, but a number of scientists, having grown fond of theories that don't lend themselves to these critieria, wish to exempt those favored theories from the criteria that apply to the rest of science. An article at Motherboard discusses the debate. Here's their lede:
Physics, cosmology in particular, is at an interesting and potentially dangerous crossroads, as argued in a recent, sharp piece in Nature by physicists Joseph Silk and George Ellis. In short, it would appear that theory, particularly neat-o ideas like string theory and the multiverse, has reached the outer limits of provability. We can't access the higher dimensions of string theory, nor can we observe (or not observe) our would-be sibling universes. Their fate is idea limbo, forever between notion and fact.Ellis and Silk are right about this, I think, but their examples are unfortunately ill-chosen. The reason both climate change and evolution are questioned by a lot of people - not just politicians and religious fundamentalists - is precisely because predictions of the former and the basic claims of the latter disqualify themselves from being considered scientific.
String theory and the multiverse are concepts that by definition defy experimentation, and yet a small movement within cosmology is attempting to make the case that they should be exempt. At stake, according to Ellis and Silk, is the integrity of science itself.
"This battle for the heart and soul of physics is opening up at a time when scientific results—in topics from climate change to the theory of evolution—are being questioned by some politicians and religious fundamentalists," the pair writes. "Potential damage to public confidence in science and to the nature of fundamental physics needs to be contained by deeper dialogue between scientists and philosophers."
Climate change proponents predicted twenty years ago that global temperatures were going to rise steeply during the ensuing decades, but they haven't. The failure of the prediction should cause a reassessment of the theory, but so far there's been no apparent inclination on the part of proponents to undertake such a reassessment which suggests that the theory is being held more as a religious conviction than a scientific belief.
Evolutionary theory, at least of the sort which goes under the name "Neo-Darwinian," holds as its fundamental claim that natural processes and forces alone have produced all the various forms of life on earth without any input from any intelligent agent. This is not a scientific claim because there's no way to test it, nor can one imagine any empirical data which would conclusively show it to be false. It's therefore a metaphysical theory not a scientific hypothesis.
In any case, Motherboard continues:
Another voice within this movement [to broaden the criteria for scientific theories] is that of philosopher and theorist Richard Dawid. Dawid argues that we can use probability as a stand-in for experiment. That is, using Bayesian analysis, it's possible to determine the probability that a set of facts fits a theory. If the probability is good enough, we can chuck testability.This is another unfortunate illustration because if Bayesian analysis is allowed to replace empirical testability then claims for the existence of God must be counted among scientific hypotheses, since many arguments for God's existence rely on Bayesian analysis. These arguments show, rather compellingly in my view, that God's existence is more probable than His non-existence. That being so, if being analyzable in terms of Bayes' Theorem is to provide us with an adequate crierion for determining what's scientific then much of natural theology, and certainly Intelligent Design, must be included under the rubric of science.
In essence, [Dawid is] arguing that theorized discoveries can be taken as evidence for fundamental theories. If we had the capability of conducting some experiment, it would probably have this outcome because the mathematics works out. Ellis and Silk argue simply that that's not good enough, for theoretical physics or any science.Motherboard finishes their piece with a very interesting statement:
The situation is similar for multiverse theories, which explain the fundamental constants of the universe (why everything is "just right" for human life) away as unspecial by claiming that in fact there are an infinite number of parallel universes composed of not just every alternative for those constants, but also any possibility for anything. Choices are never made in this reality, only new universes. There is an entire realm that exists in which I got two slices of pizza for lunch instead of three, and there is an entire realm that exists in which the strong force isn't strong enough to form atomic nuclei. Cool.
"Billions of universes—and of galaxies and copies of each of us—accumulate with no possibility of communication between them or of testing their reality," Ellis and Silk write. "But if a duplicate self exists in every multiverse domain and there are infinitely many, which is the real 'me' that I experience now? Is any version of oneself preferred over any other? How could 'I' ever know what the 'true' nature of reality is if one self favours the multiverse and another does not?" Stoners, beware.
"Post-empirical science is an oxymoron," the pair concludes.
The scientific high-ground is at stake, with an ocean of pseudoscientists ready to flood the landscape, taking the public with them. The answer, according to the current paper, lies in a simple question. What observational or experimental evidence is there that would convince a theorist that their theory is wrong? If there is none, then the theory is not a scientific theory.Precisely. Which is why so much of macroevolutionary darwinism is thought to be unscientific by such a large number of people.