One fundamental scientific and philosophical problem is determining how life began on earth as well as the probability of such a thing happening. Those who favor a purposeful universe point to the existence of life as evidence for said purpose-they claim that the odds of life just happening are far too long to explain otherwise. Those who favor that life just happened need to provide an account of how it just happened and typically want to discuss the probability of the event.
In 1970 Jacques Monod (a biologist and winner of a Nobel prize) wrote “Man at last knows that he is alone in the unfeeling immensity of the universe, out of which he emerged only by chance.” This quote nicely expressed the dominant scientific view of the time: the emergence of life on earth was 1) the result of chance and 2) a matter of such amazingly low probability that it most likely never occurred elsewhere. Of course, even if the probability of life were extremely low, it would still be a hasty inference to conclude what Monod concluded. It is, after all, a big universe.
While this view still enjoys some popularity, some scientists have started accepting the view expressed by Christian de Duve (a biochemist) who calls life a “cosmic imperative” and asserts that it should appear on any earth like world. Given that he has a sample of one (earth) to work with, his assertion is amazingly bold. This hypothesis is sometimes called “biological determinism” (not to be confused with the determinism in the free will debate, of course).
Finding life on another world, such as Mars, or even finding signs that life appeared multiple times on one world (such as earth) would help support the biological determinism hypothesis. Of course, it would require finding multiple worlds like earth with life on them to make accepting the hypothesis reasonabl. After all, finding a few worlds with life in a vast universe would be consistent with the claim that life arises by pure chance and at a very low probability.
As a philosopher, I find the debate quite interesting. After all, it is replaying debates that occurred centuries ago in philosophy regarding the nature of reality. It will be interesting to see the proposed mechanism for biological determinism. Naturally, it does seem to stray into the area of classic, Aristotelian style teleology. Of course, I think humans find that irresistible. For example, even those devoted to evolution find it almost impossible to avoid straying into talk of purpose.