Welcome to a special A to Z Challenge edition of Sciency Words!  Sciency Words is an ongoing series here on Planet Pailly about the definitions and etymologies of science or science-related terms.  In today’s post, I is for:


In 1959, this paper by Giuseppi Cocconi and Philip Morrison appeared in the journal Nature.  The ideas Cocconi and Morrison laid out in that paper were bold, and maybe a little presumptuous, but they became the foundation for a very important subfield of astrobiology: the search for extraterrestrial intelligence, or SETI for short.

The A to Z Challenge being what it is, it’s too early for us to start digging in to the subject of SETI research.  But we can talk about part of it.  Specifically the I part—“intelligence.”  It’s fairly obvious what “search” means, and “extraterrestrial” simply refers to something that’s not from Earth. But what is the definition of “intelligence”?

What does it mean to be intelligent? How would we recognize an extraterrestrial intelligence if and when we find one?  Are we sure we humans are a good example of what an intelligent life form is like?  (No, wait, maybe don’t answer that last one!)

In this article from Space.com, the famous SETI scientist Jill Tarter is quoted as saying:

SETI is not the search for extraterrestrial intelligence.  We can’t define intelligence, and we sure as hell don’t know how to detect it remotely.  [SETI]… is searching for evidence of someone else’s technology.  We use technology as a proxy for intelligence.

This reminds me of a joke from the Hitchhiker’s Guide to the Galaxy, that humans think we are the most intelligent creatures on Earth because we built cities and nuclear weapons and things like that, while dolphins believe they are more intelligent than us because they chose not to do those things.

So it is time we change SETI to SETT—the search for extraterrestrial technology?  It sounds like Tarter would support that change.  She calls the SETI acronym “problematic” and suggests that we “talk about a search for technosignatures” instead.  But as regular readers of Sciency Words should know by now, once a word gets embedded in the scientific lexicon, it’s really, really, really hard to change it, no matter how problematic it might seem. Don’t believe me?  Click here or here or here or here or here.

And I suspect that Jill Tarter knows this.  In this report on SETI nomenclature, which is co-authored by Tarter, it says, “Definitions of intelligence are slippery […]” however, “[the word’s] use in the acronym SETI is sufficiently entrenched that we recommend against a more precise rebranding of the field.”

So what does it mean to be intelligent?  For the purposes of SETI, no one knows.  The term is vague to the point of being unusable for official scientific discourse.  But scientists have been talking about and writing about this for decades—remember, that Cocconi-Morrison paper came out in 1959—so at this point we’re sort of stuck with the I in SETI.

Next time on Sciency Words A to Z, we’ll get the latest juicy gossip from the moons of Jupiter.

5 responses »

  1. In terms of intelligence, I currently favor seeing the capability to make accurate predictions in service of goals (programmed or evolved) as a good definition. Not that that helps much in searching for it across interstellar distances.

    Searching for technology also means searching for something that can both predict things and manipulate its environment for its purposes. It means they have their own version, not only of the brain, but also the hand. Dolphins, even if they wanted to, couldn’t build technology. They don’t have the appendages. A civilization requires both intelligence and dexterity.

    Liked by 1 person

    • J.S. Pailly says:

      True enough. As I’ve done my research for this A to Z series, I’ve come to realize that SETI is more about finding the kind of aliens we humans can relate to: aliens that build machines the way we do and have a society kind of like what we have.

      Liked by 1 person

  2. Liam says:

    This is all very fascinating. I like that scientists are discussing how to define these terms and use them appropriately.


  3. nannus says:

    I suggest defining intelligence as a combination of logic and creativity, where creativity is the ability to move out of the scope of any theory you can give about a being. So any formal (exact, algorithmic) description of it is incomplete. If you can describe it in terms of an algorithm (like today’s “AI” systems), it is not intelligent in this sense. They have the logic (the computational or algorithmic capability) but not the creativity. For any given algorithm (including learning algorithms), whatever is computable in them is computable right from the beginning. Whatever is derivable in a formal theory is derivable from the outset. Something cannot become derivable. In an intelligent being, what is computable or derivable can change, it can develop. Algorithms cannot do it. At the core of intelligence is creativity in this sense. If intelligent beings are creative in this sense, they do not have much of a fixed structure that cannot change. In that sense, they would all be equivalent. They would all be human, so to speak, no matter if they are Neandertals or “modern homo sapiens” or some extraterestrian. Being intelligent makes us all “not fixed” and “world open” and in that respect, we would all be the same, no matter the cultural differences.

    Liked by 1 person

    • J.S. Pailly says:

      I tend to agree with you. The issue for SETI research is how do we detect intelligence? Neanderthals are a good example. They were intelligent, but a SETI search would not be able to detect them.


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