It's an idiotic statement because life evolved for earth shouldn't survive on Mars. There is no expectation that it would.
Not all life, but some? Absolutely. Why would you think differently?
Life evolved to live in that climate wouldn't be expected to survive here.
It would be expected to survive in a similar climate. What planet that climate happens to exist on isn't that relevant. I suspect you're thinking of higher order animals, but we're talking about very simple organisms here.
It's like saying fish don't survive in the desert so there must be no life in the desert.
No. It's like saying that if no single form of life we know of can survive in that desert, then the odds of naturally occurring life in that desert are low. Because something
should be able to survive there. Life on earth is incredibly varied. Environments on earth are as well. Some of them much much more harsh than that on mars. If we can't find anything that survives on mars, then it doesn't preclude some completely different form of life evolving there, but it makes the odds much lower than if we can find things from earth that survive on mars. It's a probability statement, not an absolute one. I suspect you're just looking at it backwards. If we can find life from earth that survives on mars, then that indicates good odds that life did (or at least could have) evolved/existed on mars (at some point at least). If we can't, then the odds become lower.
It's like if you want to determine if someone could have climbed a cliff without a rope. You might find the best cliff climbers in the world and see if they can climb the cliff without a rope. If they can, then it means that someone else could have. If none of them can, then it means the odds that someone else did is low. It's not bad logic. It's quite good logic. Edited, Jan 11th 2013 2:02pm by gbaji