Re: What is the difference between intelligent life and nonsentient life?

"Say we sent a probe to Mars and it found several forms of active 
life..."

Well, as you likely know, we HAVE sent probes to Mars and did not
find any obvious life...so let's imagine that we've sent a probe to,
say, the oceans of Europa instead.  And let's imagine that in front
of our TV camera a 500 foot long squid-thing swims by...  It sure
looks alive, but is it intelligent? About the only way we could form
an opinion would be to observe how it behaved.  But exactly how
to decide is pretty uncertain -- for example, we can easily study
dolphins back here on Earth, and discover that they have very large
brains and that they communicate using complex sounds underwater, but
just how intelligent dolphins are is still somewhat controversial.  We can
say for certain that they have no hands, and hence can't be tool users
like we humans are.  Also, we can observe the fact that they are often
fooled by human fishing nets, sometimes even being killed, which suggests
that they are not smart in the problem-solving way that we are.

But are there other kinds of "smart"? If our imaginary squid-thing were to whip 
out a toolkit and start taking our probe apart, that would probably
convince most people that it was intelligent.  On the other hand, maybe
it just undulates amd does nothing much, sort of like a jellyfish.  Then
it might be hard to tell if it had any thought processes going on.
We might have to study them for a long while to see if there is any
evidence that they "understand" their environment, in particular if
they can anticipate or control events.  But we might never know for sure,
amy more than we know for SURE about some speices back here on Earth.