I've been reading a lot of history books on the 18th century recently 
and according to them, the 1720's bubble in England had a very short 
lived effect. A slight rise in suicides for the year - granted - but 
by 1721 it was business as usual and the South Sea Company itself 
continued trading for many years afterwards.

A personal argument in a paper I am writing up at the moment, is that 
there was a shift in economic thinking after 1720 focusing on 
government debts and government earnings as the benchmark of progress 
until about 1740. But this had more to do with English politics, the 
stability of  'prime' minister Walpole, The Anglo-French peace and 
the royal succession than the relatively small effects of the bubble.

John Law was more of a cause of the French bubble and did influence 
opinions afterwards, but again the crisis was not a main driver of 
change at that point. I can't think of a reference, but both crisis 
and war have tended to influence economic thinking, although the same 
can be said for booms and peaceful periods - but during the latter 
the effect is harder to isolate in the "before-after" perspective 
your friend is thinking about.

I would argue - controversially perhaps - that most economic theory 
has come from some concern about the authors current surroundings and 
events, and there tends to be more work challenging the consensus in 
a crisis (for obvious reasons), although some remain wistfully 
unaware of their surroundings. Ricardo comes to mind.

Just my two cents on that account.

Benjamin Mitra-Kahn