If you parse the article carefully, the entire argument is summarized as "There are more than 10^22 planets, therefore ETI probably exists[ed] if P(intelligent

If you parse the article carefully, the entire argument is summarized as "There are more than 10^22 planets, therefore ETI probably exists[ed] if P(intelligent life|planet) > 10^-22". Specifically, unless the probability for evolving a civilization on a habitable-zone planet is less than one in 10 billion trillion, then we are not the first. [...] In other words, given what we now know about the number and orbital positions of the galaxy’s planets, the degree of pessimism required to doubt the existence, at some point in time, of an advanced extraterrestrial civilization borders on the irrational.