It's an interesting debate, and the position I find convincing is that Say's law usually holds... except (rarely) when it does not, such as in the recent financial crisis. Believing that it always holds automatically is a fallacy of Classical economics.

It's interesting that Jean-Baptiste Say himself was willing to learn from history.

http://delong.typepad.com/sdj/2010/07/after-the-british-fina...

That's obviously false as plenty of goods are never sold but destroyed instead because nobody wanted them. Production follows demand, any businessman will tell you. Maybe if a few economists actually learned about business we wouldn't have so many recessions.

Yea and that makes sense for products that are actual necessities. It is bullshit if applied to an arbitrary "product".