Today's Economist Making the Moral Case for Capitalism
As Huerta de Soto reminds us, that "mainstream" economists not only failed to get 2008 right, they blew the whole 20th century by failing to predict the collapse of the former Soviet Union. They neither foresaw the collapse of the USSR's planned economy nor understood the fundamental, inherent problems in the world's dominant anti-market economic system of the last hundred years.
Question. Is there a thing as 'economic science'?
Answer. Yes, unfortunately there is something often called economics that is far from science. There is so little today, at least in the mainstream, of the standard of thought of those named.
What determines if it is science? It is the the thinking, the essential reference to reality. White coats, instruments, or machines that go ping, are not needed.
Another interesting point is the role of the School of Salamanca in Spain, not usually recognized. I think tho' that the inspiration came from the renaissance, the re-discovery of ideas from Ancient Greece, via the Islamic crescent, that had been lost to the west. Islam had and preserved that learning but did not use it. 'Could not' may be a better description, tho' there are some notable exceptions. Catholicism had suppressed all that did not justify its power.
Looking at the basic ideas, they are quite consistent with Rand's Objectivism.
Re. Jean-Baptiste Say, when I studied econ last C, Say was mentioned only with a put-down. As you say-
'Say’s ideas had to be crushed' since those ideas take away the justification for central planning and therefore the amount of work going to economists.