Abstract

My topic is extraterrestrial intelligence. Following current conventions, I use the abbreviation ‘ETI’ to stand for three related concepts: the abstract idea of extraterrestrial intelligence, individuals who are both extraterrestrial and intelligent, and the hypothesis that there are ETIs. SETI is the search for ETIs, and CETI is the attempt to communicate with ETIs. In this paper, I will try to answer the two most basic questions in extraterrestrial studies. First, what is the status of the ETI hypothesis? In the light of what we know, how likely is it that there are ETIs? Secondly, what is the value of pursuing SETI? Are the expected epistemic and pragmatic payoffs sufficient to warrant an extensive search? The first, substantive question is discussed in Section 2, Section 3 and Section 4. The second, ‘program evaluation’ question is the subject of Section 5 and Section 6. But first we'll take a brief look at some of the early history of the topic.