In ethology and scientific psychology, intelligence is a hypothetical construct, not a physically real entity. You can’t cut open an organism and find intelligence, any more than you can thirst. Studies that address intelligence always define it operationally. Just as the thirst of a rat may be defined as the number of hours it has been deprived of water, the intelligence of a person may be defined as his or her score on a paper-and-pencil test. Although we know that there is a physiological basis for thirst, thirst is itself hypothetical. Similarly, density of neural connections is correlated with performance on “intelligence” tests, but intelligence remains hypothetical.
I’ve spent a fair amount of time perusing SETI documents. The use of “intelligence” is entirely casual. Some in the project have preferred “civilization” to “intelligence.” SETI scientists explicitly assume that ET thinks as they do about how to contact a distant civilization. There’s implicitly an operational definition of intelligence in that.
In contrast, intelligence does some mighty heavy lifting in ID creationism. IDCists believe that non-material intelligence, and nothing else, creates special kinds of physical information. But what is intelligence? Ruling out matter and energy, we’re left apparently with information. So information creates information ex nihilo? That’s a nonstarter. Intelligence must have a special ontological status.
Gee, what could this entity that creates physical stuff out of nothing be? Do you suppose that IDCists believe that creative intelligence is spiritual in essence? There is, of course, no way for it to be anything but in the belief systems of almost all of them. Far be it from me to criticize personal belief in creative intelligence. But I have huge problems with people who pretend to have raised a challenge to evolutionary theory that is scientific, when they know that it is at core spiritual.