[To be sung to the tune of Gilbert and Sullivan’s “Modern Major General“]

In microeconomics, S and D curves must equilibrate;

It’s a fact which ev’ry laissez-faire economist must celebrate.

Under classical assumptions, as set down by Dr. Marshall,

Markets always clear, although the equilibrium is partial!

And with perfect competition, to the best of our ability,

Then the quantity and price are such that maximize utility.

And although the notion may seem so simple that it’s risible

Even so, the market‘s guided as if by a Hand Invisible.

And at the risk of being just a little bit repetitive

This is why we mustn’t intervene when markets are competitive—

It’s a fact which ev’ry laissez-faire economist must celebrate—

In standard economics, S and D curves must equilibrate!

————————————————————————————————————————–

So effective is the model at describing price behavior,

There are those who’ve come to see it as an economic savior.

As a market functions best when its preserving its autonomy

They use this very model for the whole macroeconomy.

And according to the principles which I already mention,

Conclude that never is there need for a market intervention.

“Recessionary gaps” they will dismiss as sheer vapidity,

And they will see no sign of traps constraining the liquidity.

But there’s a little problem, in that when they do extrapolate,

The similarities with micro will, alas, evaporate.

But even so, ev’ry laissez-faire economist will celebrate:

In economic models, S and D curves must equilibrate!

————————————————————————————————————————–

There are analogues in science that I’ll tell you if you want ‘em:

Physics, for example, has mechanics classical and quantum—

The former is for apples and for other common articles,

While the latter is designed for use with sub-atomic particles.

Although in single markets laissez-faire is unassailable,

That doesn’t really mean that it is infinitely scalable.

For when on a certain field is where all of your reliance is

You hope that it would have the rigor of the other sciences.

And so my final verdict, I’m afraid, is very critical:

As long as economics is so thoroughly political

The best that we can hope for is economists who celebrate:

In economic models, S and D curves must equilibrate!