There is proof that there must be life on other planets. The proof is logic. It is completely illogical to think that there is absolutely no life anywhere but earth just based on the size of the universe. Mathematically, there are so many combinations of different conditions that life must be sustained on other planets.
The con argument enters that evidence has not been uncovered nor published suggesting alien life. However, they discount the statistical probability which can equally serve as evidence. With 900 billion planets and an even greater number of moons in just our tiny suburb of a galaxy, and an unknown but likely near infinite number of galaxies, the chance of their not being life is infinitesimal. Many planets have been discovered and observed to have the right conditions for life, but none have had that happy accident that likely began life on earth. So there is a very strong case for extraterrestrial life, where the statistics serve as proof.
I believe there's life on other planets. I also believe the universe is infinite which would make life on other planets an inevitability. However, there's no proof the universe is infinite and there's no findings of life on other planets. Hence, even though it's probable, it's not proven.
I do think that there probable is live on other planets, but so far there has not ever been evidence that shows a for sure life that is on another planet. Maybe someday soon, with our new technologies, we will see other life on another planet, and check em out.
I'm not sure if there is life out there beyond earth, but there has been no clear example or proof that there is. So thus my answer is that I don't believe there is actual physical proof. However I do believe that there has to be something out there because how can we be the only living organism in an infinite galaxy. But for now, there is no proof and can't say there is anything out there.
I do not believe there is proof of life on other planets in our possession at this time. There has been controversial evidence but that to me is not proof as most people prefer. I believe there is life out there simply given the vastness of space and all of the planets we already know about.
I believe there is life on other planets; in fact, I believe that the universe is teeming with life. What I do not think, though, is that we have yet to find any evidence of this. If we were to find it, it would be all over the news. Especially if it wasn't intelligent life.