PKT message, Economics, logic, and ideology

The following off-list message on the relationship between conceptual clarity and ideology in theoretical economics follows up on my recent postings on the Closed vs. Open System attributes of the General Theory model sketched by Keynes in Chs. 4 and 6.

My own summary statement of this view of things is that the premises of
one's argument must be internally complete, coherent, and consistent - or
else one's argument itself is incomplete, incoherent, and inconsistent.

The "ideology" comes in when mainstream, monetarist, and ELR theorists
refuse to admit this nearly self-evident point lest its acceptance upset
their respective apple-carts.

In this respect, Milton Friedman stands out among other leading theorists in
that he does not shy away from acknowledging the fact that logical coherence
and consistency is not of primary importance for his brand of would-be
theoretical economics:

"Logical completeness and consistency are relevant but play a subsidiary
role; their function is to assure that the hypothesis says what it is
intended to say and does so alike for all users - they play the same role
here as checks for arithmentical accuracy do in statistical computations."
('The Methodology of Positive Economics', in 'Essays in Positive
Economics'.)

What Friedman does NOT acknowledge is that, absent internal completeness,
coherence, and consistency between his premises, it is logically impossible
to formulate "hypotheses" whose meaning is (a) unequivocal, and (b)
understandable.