Beings are possible together, in turn, when they do not enter into contradiction with each other. For instance, it is logically possible that a meteor might have fallen from the sky onto Wikipedia founder Jimmy Wales’s head soon after he was born, killing him. But it is not logically possible that what happens in a given world (e.g. that Jimmy Wales founded Wikipedia) also does not happen in the same world (i.e. that Jimmy Wales did not found Wikipedia).