To address a few of the points arising in this discussion:
In the absence of direct evidence it is impossible to be sure of life other than on this planet.
However, our observations of evolutionary patterns and constraints are strongly suggestive of an underlying universal structure such that directionality is impressed upon stochastic processes. It is quite wrong to jump to the conclusion that this implies any kind of "creator", "intelligent design" or "goal". It simply means that that that is the way nature's machinery happens to work. So from this heuristic standpoint we can reasonably guess that other instances of the overall life process may well occur. Certainly that part of it which corresponds to the formation of the chemical elements in stars and supernovae is very common. Events further "downstream", the formation of solar systems, some having planets which meet the very tight criteria for the initiation of biology, and the even tighter requirements for the eventual development of large multicellular organisms of course become increasingly rare.
The further requirement for timely availability of materials such as glass, copper and iron to enable the evolution of technology within the collective imagination of a species such as ours providing a further constraint.
However, as evidenced by the billions of sperm sometimes released for the production of a single gamete, we see that nature's machinery has little regard for economy.
Another issue is the use of the word "intelligence" which is responsible for much of the woolly-mindedness that is found in debates such as this. The special adaptation of our particular species, the ability to generate and morph extraordinarily complex models of the external world within our minds is far more accurately described by the word "imagination"
Our current understanding of biology, particularly its evolutionary aspects, lead us to the inevitable conclusion that all animals must have imagination. It corresponds to the navigational feature which enables an organism to optimize its interaction with the prevailing environment. The difference between species is quantitative, not qualitative. For a bacterium it minuscule.
For a snail it is tiny. For the human species, whose level of interaction with its environment is extraordinarily high, it is immense. Importantly, human imagination is not limited to the individual, as is largely the case in other creatures.
Human imagination is greatly amplified by virtue of the fact that it is exported and imported between individuals. It is also stored externally on such media as paper, more recently, magnetic, optical and electronic devices.
This collective sharing and storing of imagination is what we call "language".
and electronic. Forget the vague and silly word "intelligence". Imagination, essentially a navigational feature, says it all.
These issues are examined further (very informally) in "The Goldilocks Effect: What Has Serendipity Ever Done For Us?" , a free download in e-book formats from the "Unusual Perspectives" website.
Regarding Jupiter's moon Europa:
To add to the other comments here it should be borne in mind that the generation of even the simplest life would seem to require a energy gradient much greater than that provided by its sunlight or by tidal flexing. By virtue of its low mass, about one hundredth that of Earth, the temperature of its core will be far less than that of Earth and the likelihood of comparable deep sea vents very low. The deep sea vents are currently prime candidates for abiogenesis on our planet, especially the alkaline ones which provide cellular matrices that could possibly provide an answer to the very intractable problem of the origin of the cell. (This is well described in Nick Lane's excellent book "Life Ascending" which will almost certainly be found in your public library.)
So the odds of even bacterial life on Europa must be vanishingly small. Water is a prerequisite for biology but only one of many.
As far as the evolution of more cognitive or imaginatory (sic) life is concerned, I think that it is a given. Inasmuch as a new non-biological life-form is emerging right under our noses!
Very real evidence indicates the rather imminent implementation of the next, (non-biological) phase of the on-going evolutionary “life” process from what we at present call the Internet.
It is effectively evolving by a process of self-assembly. You may have noticed that we are increasingly, in a sense, “enslaved” by our PCs, mobile phones, their apps and many other trappings of the net.
We are already largely dependent upon it for our commerce and industry and there is no turning back. What we perceive as a tool is well on its way to becoming an agent.
This line of thought is developed further in my book "Unusual Perspectives:An Escape From Tunnel Vision"
28 Aug 2012, 12:39 pm
