Whose models are these?

John Maynard Keynes was born in 1883 and died in 1946. His career was largely based on his explanations of events surrounding World War I and the Great Depression. Given that the popularity of Keynesian economics is almost entirely a post-World War II phenomenon, Keynes did not live long enough to comment on the vast majority of the economic theories put forward in his name.

"Mr. Keynes and the Classics"

Consider, for example, the IS/LM Model that is at the
center of discussions of Keynesian economics. In 1936, Keynes' published
his
General Theory of Employment, Interest, and Money. The next year,
Sir John Hicks published "Mr. Keynes
and the Classics: A Suggested Reinterpretation" (*Econometrica*, April
1937). Hicks' attempt to explain Keynes' work introduced the
IS/LM Model. Even
the IS/LM Model is thus an interpretation of Keynes' thoughts rather than a
specific statement by Keynes.

In fact, Hicks described the IS/LL Model, not the IS/LM Model. The notation IS/LM first appears in Alvin Hansen (Monetary Theory and Fiscal Policy, 1949). The IS/LM Model thus appeared three years after Keynes' death.

So, whose models are these?

The models presented here are all "modern" interpretations of prior writings. They benefit (or suffer, depending on your point of view) from decades of advances in graphical presentation and mathematical analysis. While it makes no sense, at this point, to discuss macroeconomics without the appellations classical and Keynesian, the focus here is on whether business cycles arise from aggregate supply shocks or aggregate demand shocks.