Steven Kates makes some thought-provoking comments, some of
which might be read in ways not quite the intended one.
a) "aggregate demand failure" is not necessarily the same
thing as "over-production" -- presumably a sudden fall in
AD, immediately resulting in a corresponding fall in AS,
would count as an explanation of the resulting recession?
b) to the extent that changes in AS lag those in AD,
over-production would be a *consequence* of recession.
One could assert both the above without holding that
"over-production causes recessions".
I don't think Keynes has to be read as making the last
claim mentioned, but it would seem that Steven does
-- so this is a request for suggestions for further reading.
Dr Julian Wells