Is it theoretically possible to alter the future without causing a paradox?

I think paradoxes occur when you travel to the past. Space/time is a tricky thing to get your head around (paradoxes and stuff like that are only guesses). If you travelled to the future and met your future self, and your future self said he needed your help, every second you spend with him is making him not you, since you know what will happen, and that can change it. Or, (this is my theory) meeting with your future self can actually influence yourself to become your future self.