That is something economists have major disagreements about. Classical economists (see Say's law) would argue that the production of a product creates the market/demand for it.
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.
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.
