However, deriving a result from a set of assumptions should not be confused with science.
That's how mathematics itself is done... you don't consider Mathematics to be a science?
Science in the classical definition meant "field of knowledge" - in that sense it is. But in the modern, more strict definition of science it doesn't qualify ("natural science" - as described by Sir Francis Bacon, XVII century). It's still the philosophical base for most if not all relevant science.
I brought this semantic distinction in the first place because non-sciences like economics don't prove anything at all in the real world and only give degrees of certainty in repeatable scenarios. In this case they are basically applied statistics.
The author(s) here are making highly speculative assertions about unprecedented situations without providing much base for them and taking a lot of dubious preconditions for granted. This level of discourse is very common in economics and sociology, even at academic levels. Just look at keynesianism.
That is a bit of a stretch. Keynesian makes up a large minority viewpoint in academic macroeconomics. It is not dominant. It is only among government policymakers that Keynesian is the dominant viewpoint.
[Don't get me started on Austrian economics because that is complete wackjob rubbish that asshats believe in. I'm not responding to asshats here. It is not an enjoyable use of my time.]
It is not that Keynesian is necessarily wrong. In fact, I think it is correct, but exceptionally difficult to prove or disprove. From the empirical side, it is impossible to perform random experiments with national economies. From the axiomatic side, it is very difficult to derive a Keynesianism model based on seemingly sensible assumptions. The typical assumptions are that people are rational, have rational expectations about the future, and that prices adjust freely.
However, this is not surprising. The idea that people behave irrationally is at the core of Keynes' thought... "animal spirits" and such. If you allow people to deviate from rationality, then the axiomatic approach becomes pretty useless. People can deviate from rationality in many ways. Oftentimes there are multiple types of deviations which could generate similar macroeconomic data. That is multiple potential axioms could be broadly consistent with the same data. In this case, who is to say what the right way to set up axioms is? It becomes faith-based. This is like math, where people can disagree about whether parallel lines ever meet. This kind of theorizing is pretty useless in my view.
By the way, Francis Bacon and the scientific method is what I have in mind when I think of science.
The economics that I do is more in the way of applied statistics as the person above mentioned. It is not very scientific though it strives to be. The point is to tell a convincing story, where your audience believes you have thoroughly analyzed a situation and considered many possible explanations for it. There is no sense of certainty like you get in the natural sciences in which I did research prior to becoming an economist.