The problem the paper is trying to address is that whether Fermi’s paradox is truly Fermi’s original idea and whether it is a paradox or not. This is important because the misinterpretation of Fermi’s original idea has lead to two time cancellations of NASA funding for SETI.
Fermi’s original question was “where is everybody?” which did not question the existence of extraterrestrial intelligence. He was questioning the feasibility of conducting interstellar travel. However, Hart (1975) and Tipler (1980) mistakenly treated this question as a conclusion which is the aliens do not exist because we do not see them. The difference between the two is that one is a question and one is a conclusion.
Further, the author argues that the Fermi paradox which really should be called the Hart-Tipler argument is not a paradox. Instead it is a reductio ad absurdum argument. They are disproving the existence of extraterrestrial intelligence by showing the absurd results they will get if they assume the extraterrestrial intelligence exists. However, there also exist many preconditions Hart and Tipler assumed for their argument which includes the feasibility of interstellar travel, the lifetime of civilization. They made assumptions which might not be true. Therefore, their conclusion depends on the assumptions they make. So it is not a true paradox since we can tweak the assumptions and make the counter argument.
The author also rebuts a similar argument which is there is no other extraterrestrial intelligence because we have not detected anything. The author argues that the incompleteness in the searching for SETI signal could be the real cause of not detecting anything.
My takeaway for this paper is how easily people will misinterpret other people’s ideas. Especially I think for Fermi’s case, the reasons this happened is because Fermi has never published his idea and he was already dead when the Hart and Tipler papers came out. If he was alive, he would clarify his argument clearly and it will not be called Fermi’s paradox today.