Actually I don't like the LK Essay. The main objections to the OP seems to be on my single reading:
(1) the number of parameters for intelligent life may be correlated such that the possibility of getting a jackpot-planet is higher than the product of the marginal probabilities: "The first is a familiar mistake of elaborating all the factors responsible for some specific event and calculating all the probabilities as if they were independent. "
(2) life may originate under very different circumstances: "And we now understand that, even in our solar system, there are a host of possible sites where life might have evolved that were long considered unlikely. Moons of Jupiter and Saturn may have vast oceans of liquid water, underneath ice covers, which are heated by gravitational tidal friction associated with their giant hosts. "
The problem with (2) is that the argument in the article is that the probability that life originates on a planet depend on a number of factors, period. So to say that life may originate under other circumstances is thus simply ignoring the claim. To circumvent the argument Krauss should demonstrate that the quotes used in the article relates to earth-like life, or that the claim itself is wrong because it makes false assumptions. I don't see how this is done without addressing the claim.
Regarding (1), it may be true the parameters are correlated, or they may not be correlated. If they are correlated, they may be correlated in a favorable way or an unfavorable way. For krauss to say they may be correlated in a favorable way is thus to make two assumptions which he does not support and to my mind requires evidence: (a) that the parameters are correlated (b) that they are correlated in a way that place more (and not less) probabilistic mass on earth-like planets.
Now, I don't buy the argument in the article one bit and the first thing i would look at was where the 200 parameters come from and what sort of range they have, however I don't think Krauss really does that asides offering his informed opinion.
