Are the multiverse theories scientific?

Virgo galactic cumulus

In previous posts I have said that the theories of the multiverse (there are several, some of them contradictory to the others) are not scientific, because it’s not possible to prove them false, according to Karl Popper’s criterion: a theory is not scientific unless it can be proved false with an experiment.

A recent article by Man Ho Chan reviews and refutes various attempts to claim that multiverse theories are indeed scientific. Here I am going to speak about those that try to prove that the multiverse theories should be considered scientific without asking big changes to the current criteria. Carroll 2018 uses three main arguments to justify this:

Anti-realist answers to the no-miracles argument

Hilary Putnam

The previous post described the no-miracles argument, proposed by Hilary Putnam. The article ended thus:

What do anti-realists answer to this argument? Are they convinced?

I guess the readers have deduced that the answer to the second question must be negative, otherwise the debate between realism and anti-realism would have ended. Let us look, therefore, at the answer to the first question. Faced with the abductive argument of no-miracles, anti-realists answer in two different ways:

1.      Bas van Fraassen is an anti-realist American philosopher who criticizes Putnam’s argument, arguing that scientific theories are successful because unsuccessful theories have been eliminated by natural selection (i.e. scientists have ruled them out). Therefore, asking why science is successful is similar to asking why basketball players are tall: because they have been selected. Let us see how Fraassen describes his theory, which is called constructive empiricism:

Abduction and the no-miracles argument

The Cheshire cat,
famous invisible cat

In an earlier post in this blog, I explained with an example the mode of reasoning based on abduction. Although not as strong as deduction and induction, abduction reaches high degrees of confidence in fields such as history, art criticism and others, less scientific than mathematics or natural science.

In another post published in March 2016, I described the fallacy of the invisible cat, which confuses a sufficient condition with a necessary condition for something to happen. This situation occurs when there are several possible causes that may have given rise to the same phenomenon.

In some cases, if we apply abduction to a situation where the fallacy of the invisible cat could occur, a conclusion can be reached. Think of the example I proposed to describe this fallacy: