Rational here means to me comparing (as in ratio, to compare)

So I would envision that it would mean people talking and finding out validity of statements made. If you come with a Mirror tabloid article that says that Coronavirus turned people into vampire zombies, that would be a much different discussion than discussing the minutiae of a topic.

The problem is “side thinking” and not enough “gradient thinking”

We might not know some of the finer details, but by inquisitive discourse we can come to a ballpark for your example, or identity problems with each method.