The fallacy of diversion is committed when one changes the issue in the middle of an argument. A common form occurs in regard to human actions and their consequences. Virtually any action has some effects that are not intended and often not even foreseen. The fact that your action had a certain consequence, therefore, does not necessarily mean that you intended it, and I would commit the fallacy of diversion if I tried to prove your intent solely by showing that the action did have that consequence.
Another form of diversion is called the straw man argument. This fallacy occurs in debate when someone distorts an opponent's position, usually stating it in an oversimplified or extreme form, and then refutes the distorted position, not the real one.