I'm not sure what you mean to be saying with all of this. I grant that there's such a thing as knowledge of economic matters. Not all knowledge has to be scientific, let alone the most rigorous, exact kind of science. The question isn't whether economists know nothing at all, but whether their discipline is as scientific as they make it out to be.

Indeed, economists must take into account decisions, as you say and as I point out in the article. Not just decisions but all the rest of subjectivity, which makes economies quite unlike objective nature. Why, then, should we expect economics to be as exact or as rigorous as physics? Why are economists so envious of physics?

I also don't see how economists have more self-knowledge than physicists just because economists talk more about a null state (such as bankruptcy?). I don't know if the concept of absolute nothingness is relevant to either economics or physics.