Interesting point brought up by Richard Dawkins:
If we make an arbitrary chance of life arising on any given planet, even if we make it extraordinarily high, it will stilly almost certainly result in many planets with life on them.
Let's use Dawkins guess that 1 in 1 billion planets are capable of harboring life. That's pretty slim odds of any given planet having life on it, enough to satisfy even conservative estimates.
Astronomers calculate that between all planets in all galaxies, there are at least 1,000,000,000,000,000,000 planets in the universe. That's one billion billion, conservative estimate.
That means that there would be, using the above figures, roughly a billion planets with life on them in the universe.
Almost no matter what odds you use, you will find that astronomical figures produce surprising results.
The real question then is not "is there life out there" but "is it anywhere that we'll ever know about it?" Remember, the vast majority of the billion billion planets roughly estimated to exist in the universe are in other galaxies and therefore nowhere even vaguely within reach of earth. Even planets in our own galaxy are mostly well without our reach even at the speed of light.
"The devil I'll bring you," answered Hagen. "I have enough to carry with my shield and breastplate; my helm is bright, the sword is in my hand, therefore I bring you naught."