To give you an illustration, imagine there's only one dollar and only one kitteh to spend that dollar on. The kitteh is worth a dollar. If another kitteh appears (our kitteh was preggers), each kitteh is now only worth *half* a dollar. Deflation. Print another dollar? Each kitteh is now worth a dollar again.
This is a difficult-to-discover cheat. The price has "stickiness". If it used to be one dollar per cat, then if there are two cats now and still one dollar, each cat still worth one dollar, and it is possible that they are not for sell so there is no need for extra dollars. Printing one dollar at mean time equal to stealing from the added production
The real question is: Are people really so stupid that without enough dollar they can't do the trade? It seems the major economy books think so
(I'm printing dollar to buy your goods because without my printed dollar you can't trade!!!)
People's stupidity is absolutely irrelevant. If a dollar which bought one kitteh yesterday is not enough to buy one today, that's price inflation. If it can buy moar than one kitteh, that's price deflation. Nothing tricky here.
You may be thinking about monetary inflation, which is defined as "We just printed moar money!" In that case, printing more money does result in monetary inflation -- by definition.
Too many people use the word inflation without thinking about what, exactly, they're trying to say. Monetary inflation may result in price inflation, but not always. For instance, if our kitteh is slutting around, we can print money with impunity without causing inflation. The nice people in charge of the money factories pay close attention to our kitteh, and know just what to expect when she's on the prowl