In a volume "Foundations of Research in Economics" edited by Medema
and Samuels, Krugman has a chapter, "How to be a crazy economist" in
which he talks about the value of economists studying HET.

Before becoming too critical of Krugman, it is interesting that his
remark on the dominance of a free market orthodoxy, which is a
historical interpretation that requires careful analysis of
economists' beliefs and the context in which they occurred, was
"translated" in the posting into the different question of whether
"all pre-1936 economists were laissez faire advocates"? It this
statement, not Krugman's statement, that is trivially and obviously
wrong.

My guess, which may be wrong, is that Krugman knows perfectly well
that economists opposed laissez faire before 1936, but considers that
it was laissez-faire advocates who were, in the context in which he is
interested, generally in dominant positions, That belief may not be
justified, but it needs to be argued in relation to context.

Roger Backhouse