[HarHarVeryFunny]

Intelligence is a capability not a mechanism, and therefore if you're able/willing to define what that capability is, there should be no problem measuring/gauging the intelligence of any system, biological or not. You don't need to look inside the black box - you only need to test if the black box has this capability.

Intelligence may be a fuzzily defined word in everyday usage, but I don't think it's the mystery you present it to be. Joe public may argue against any and all definitions of the word that they personally disagree with (maybe just dislike), but it's nonetheless quite easy to come up with a straightforward and reductive definition if you actually want to!

[sfpotter]

You and I are clearly referring to two different things when we use the word “intelligence”. It is also not nearly so easy to come up with a simple/mechanical/verifiable definition for the thing that you’re referring to. Unless you have a good definition—in which case, you might want to put your money where your mouth is and get busy revolutionizing multiple fields of human inquiry!

It’s also plain that many people are very interested in looking inside the black box and think the contents of the black box are relevant and important. This fact doesn’t change just by your saying so.

[HarHarVeryFunny]

People are interested in looking inside the black box (our brain) for sure, partly for inspiration as to how to implement intelligence among other things, but implementing isn't the same as defining.

Being able to define what you want to achieve isn't generally the same as knowing HOW to achieve it (except in this case the definition of intelligence rather does suggest the right path).