I've just watched a show on Discovery (yay, annual leave about life being elsewhere in the solar system (europa's seas) or elsewhere in the universe, and the search thereof.

I was happily digesting a sandwitch and Tooheys when a silvery senior figure from NASA tried to quell the discussion in saying that single cellular life would be a significant find.  Speculation followed from the usual sources, with counter arguments from again, usual sources.

Please people!  enough.

Once you start a back-and-forth on semantics of proof (not to mention some very poor web design there guys!) you are already on the wrong path.

Bill Bryson concluded that life doesn't want to be much.  No social commentary intended, just his noting that of all living creatures, only one species has been so motivated to write books about living species.  The rest are just content to be moss, plants and etc.

Are Bryson and our aforementioned NASA silvery senior on the right path?  Maybe.  In either case, consider if "life" were substituted with "a mere inevitable chemical reaction"; if so Bryson should be careful to attribute "want", and our silvery senior should be careful when attributing "life" to it also.

Jon Kabat-Zinn noted that our subspecies name of Homo sapiens sapiens is no mistake, sapiens derives from the latin sapere, to taste but also to know.  The word sapient derives here also- meaning wise and insightfil, but isn't in wide use in present day English - maybe there is less call for it these days?   But seriously, the use of sapiens sapiens implies a meta awareness.  Man who knows and knows that he knows as Kabat-Zinn puts it. 

And this is exactly where the wheel comes off the cart for the extraterrestrial life argument.  Where can the term life be defined outside the realm of subjective experience?  To be alive and not know it renders me unable to describe life.  If we sustain that line of reasoning one step further, any concept dependant on a definition and description of life, be it religion or God, can only itself be described in the context of a subjective description.

While ever discussion of these matters is bound by shifting semantics of language, you will find me perched on an esky at the sideline tossing my empties into the skirmish.