Bryan Caplan argues that the recent crash was caused by animal spirits.
But I saw the 2008 crash and subsequent downturn with my own eyes, and I’m convinced that mood played a key role. The world freaked out, big time. It was the economic analog of a riot.
I was there also, and it was entirely rational for everyone to try to get to the exits before everyone else.   No animal spirits involved. In 2005 November I said “Now is the time to panic”, so I got to the doors comfortably enough, though it was starting to get crowded and a rush was setting in. By 2008 – well if you had not realized it was time to get out before 2008, it was indeed the economic analog of a riot.
In 2005 November I was talking to real estate valuer, who told me that lenders were getting nervous about wildly inflated valuations. I immediately saw what would unfold. Real Estate prices were going up because people, mostly cat eating Mexicans with no money, no jobs, no prospects, and a past history of never paying their debts, were buying houses at inflated prices with no money down, and since they were not putting any money down, did not care how inflated the price was. Obviously this could not go on, and when it stopped, everything was going to go to hell. So as soon as some people thought it was going to stop, they ran, and as soon as they ran, other people started to suspect it was going to stop, and they ran also, until by 2007 it was a crazy rush to get out, and by 2008, too late.
So when I learned in 2005 November, that lenders were getting nervous, I realized that the rush to exits had begun, and immediately joined it.
Everyone knew that things were going to collapse, but wanted to stay in till the last minute because there was money to be made, so it was not animal spirits, but people trying to judge when to run to the exits.