answer:To my way of thinking, the terms in these kind of scenarios are pretty much equivalent. No matter how you look at it – especially in terms of extraterrestrial life – saying “I think they have” or “I believe they have” are the same thing. No one has proof, and no matter which word you use, you’re still expressing a feeling on the matter. That’s generally why, whether one says “believe” or “think”, they tend to follow it up with, “but of course I can’t know for sure”. If they’re logical they do, anyway.