However, Roger Farmer at UCLA says we should take the stock market's message seriously. There is, he says, a "strong and stable connection between persistent changes in the value of the stock market and changes in the unemployment rate", with rises in the stock market leading to falls in unemployment.
"The stock market matters for the unemployment rate: and it matters a lot," says Professor Farmer. So much so, in fact, that he believes the Fed should use share prices as part of monetary policy, buying ETFs to drive prices up in bad times and selling ETFs to drive them down in good times.
This, he says, is because share prices can be driven by self-fulfilling beliefs. If people anticipate good times, share prices will be high so investors will be wealthy and spend more and the cost of capital will be low, prompting firms to invest more. This will be the case even if those anticipations were, initially, unfounded.
If this is right, the economy could prove to be stronger than economists expect.
But is it right? Sir Mervyn King, the former Bank of England Governor, used to say that in considering the effects of a change in asset prices one must always ask why the change happened.
It's certainly true that economies can sometimes believe themselves richer. This happened during the tech bubble.
But there's another possibility. It could be that share prices have risen not so much because people anticipate good times but because low interest rates have caused them to chase risk and to drive prices higher without any improvement in the underlying economic outlook.
You might wonder why this matters. After all, even an "irrational" rise in share prices makes people richer and cuts the cost of capital, both of which should stimulate the economy.
I suspect it might, for one reason. Wall Street's optimism is not wholly shared by Main Street. Although consumer confidence has risen sharply since 2009 it is still below the levels we saw in the late 90s and mid-00s. And non-residential investment has fallen in each of the past three quarters. These two facts suggest that, at best, there might be sand in the wheels of the mechanisms which link today's share prices to future aggregate demand. And at worst, they corroborate fears that high share prices are due to an unsustainable reaching for yield.
Personally, therefore, I'm not confident that high share prices right now are a harbinger of better times. Nevertheless, I admire Professor Farmer for correcting macroeconomists' tendency to neglect stock markets, and for reminding us that sentiment can matter enormously.
