It isn't affecting the world wide commodity markets..... I understand your answer in reference to America, but world wide? It's the fact that capitalism embraces the highest bidder. Speculation on commodity futures in the various world markets is where the inflationary pressure is coming from. In fact, with world markets linked as they are with technology of today, a single entity could attempt to corner the futures market on a specific commodity if they had enough to cover the call.
While the majority of inflation is indeed caused by a rise in available currency, history has shown that there are other inflationary pressures as well, such as a perceived or actual shortage of a commodity. Speculation that a certain commodity may be scarcer in the future also contributes to inflation. Your argument is only standing on one foot. Take a look at the other causes of actual inflation and forget the book definition for a second...