We are not completely sure that there is no life on any of the other planet and that is one of the things that space exploration is trying to find out. But we do know that for life to exist, certain conditions must be present. All living things require certain things like light, water, food, oxygen and the right temperature.
Do all the above-mentioned conditions necessary for life exist on any other planet? It does not seem that way, judging by what we know so far about conditions on the other planets.
Venus is more like Earth than any other planet, but the surface is approximately 800℉. Life as we know it could not exist there. Planets like Jupiter and Saturn are covered by very thick layers of clouds made up of gases that are poisonous to us. Each planet seems to have some conditions that either make life impossible or do not have the conditions necessary for life.