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I'd say that at this point we are largely ignorant of the odds of intelligent life existing in a solar system. While at least some basic forms of life ought to be plentiful in the galaxy, the conditions for evolution from simple life to intelligent life (that is, civilization-building life) just aren't understood to the level that would be required for ANY probability estimate to be given. Note that I'm not saying intelligent life is rare; I'm just saying that both scarcity and abundance of intelligent life are consistent with our current state of knowledge.
But that's just the prior probability. I can still say that we have strong evidence that the probability of a given solar system having intelligent life is much, much lower than one in 150,000.