Whew, Dr. Bill, what an article! He got into WAY more depth and detail about measuring than I have much interest in any more---made me think I was back in school! But I have copied several things that I thought might foster discussion. The three def.'s below are part of what he calls "psychometric views of intelligence". He later compares this to what he calls "the cognitive-psychology view".

Fluid intelligence is the ability to develop techniques for solving problems that are new and unusual, from the perspective of the problem solver.

Crystallized intelligence is the ability to bring previously acquired, often culturally defined, problem-solving methods to bear on the current problem. Note that this implies both that the problem solver knows the methods and recognizes that they are relevant in the current situation.

Visual-spatial reasoning is a somewhat specialized ability to use visual images and visual relationships in problem solving--for instance, to construct in your mind a picture of the sort of mental space that I described above in discussing factor-analytic studies. Interestingly, visual-spatial reasoning appears to be an important part of understanding mathematics.
==========================================================

Cognitive psychologists think of thinking as the process of creating a mental representation of the current problem, retrieving information that appears relevant and manipulating the representation in order to obtain an answer. The problem, its solution and some of the methods used to solve it are then stored for later reference.
==========================================================

The cognitive-psychology view is that cognition is a process, whereas the psychometric view makes it a collection of abilities.
==========================================================

This one put a wry smile on my face! My score on the Mensa test is, I think, a more accurate proof of either my test-taking skills or that they need to revise their test, than it is of my intelligence: I scored at the 99th percentile, and I am not a super-genius by anyone's measurement!
In economic terms it appears that the IQ score measures something with decreasing marginal value. It is important to have enough of it, but having lots and lots does not buy you that much. My regrets to Mensa, but that is the way things are.
=========================================================

In summary, it appears that IQ is an important factor in getting into a job or profession, but is less important (although not negligible) once you have learned to do the job. Further improvement is then achieved by acquiring experience, rather than improving upon an abstract knowledge of what the job requires.

==========================================================

Within the framework of the psychometric definition, in fact, the evidence is quite clear that intelligence is substantially inherited.
==========================================================

The sociologist Christopher Jencks (1992) has observed that genetic explanations that stop with a heritability coefficient are unsatisfactory because they do not specify how intelligent behavior is produced. No one inherits an intelligence-test score in the sense that one inherits eye color. What must be inherited is a physiological capacity for paying attention, learning and reasoning that allows us to extract from our experiences the knowledge and problem-solving techniques required to solve test problems. We have very little idea about what these physiological mechanisms might be, especially insofar as they are related to variation in abilities within the normal range of intelligence.
==========================================================

I suppose I agree most with Mr. Jencks. However, while I agree that a certain level of basic capability is required,
I strongly believe that it is possible to increase intelligence, by stimulating the thinking capacity of children from infancy into the school years. To our amazement, our daughter toddled over at age sixteen months to point to the back of the newspaper that my husband was reading, and accurately said, "K". What she was looking at was an ad for Kroger, where when I took her grocery shopping, I would point out the giant blue K on the front of the building. So, taking my cue from her, I set about teaching her the alphabet. Not being a teacher, I didn't know how to go about it, but it seemed to me that o had the simplest shape, so that is the first letter both my kids learned. Once they recognized that on a flash card, I then
started to "hide" two cards together--sticking out from the sofa cushion, maybe. One would be the o, and the other might be A. I would tell them, "Bring me the A", and they'd scamper off, delighting first to "find" the cards, and to figure by the process of elimination which one must be the A. I repeated this method with all of the letters,
hiding A (when I was sure they knew it), and a new letter, leaving what seemed to me the most difficult ones (B, for ex.) till last. Our daughter knew all the letters by 22 months, and our son by 26 months. I set lots of little puzzles for them to solve--things we came across in everyday life--and we did experiments, etc., and generally just had a ball, pretty much clear through elementary school.
And they are smart! I think they did have a good basis from which to build, but I also believe that had I simply let them play, and never had them do anything that fostered the acquisition of thinking skills, they would have had a much, much harder time in school. It is beyond me how parents in the civilized world these days can let their child start kindergarten totally ignorant of not only the alphabet, but such basic things as colors.