A psychologist, educator, employer or just good friend may ask you one day to take an IQ test, to know your real worth and potential, and which niche/stratum in society you fit into best. Doubting their motive, knowledge or even IQ, you wonder, "Is measuring intelligence an intelligent thing?" One needs to investigate the validity of tests in the first place before taking them, before submitting oneself to the so-called elite or intellectual superiors, who usually control such tests, to trust their tools and motives.
Most tests are based on retaining data and figuring out relations between shapes, numbers, or words. This is usually easier for people working in fields dealing with such entities: engineers, mathematics teachers/students, language teachers/students, lexicographers, and other specialists who do better than most people in such tests, each in their respective field.
Some psychologists realized this defect of IQ tests, so they came up with the "culture-fair" tests. As the name suggests, they are culturally and educationally unbiased: there are no words, no mathematical problems or language quizzes; there are only shapes. But then again, the shapes require a geometrical background, and inevitably some logical thinking skills and mathematics, that some are good at by "nature" or by "experience". Just naming the different geometrical shapes and operations is vital to process them faster:
Those tests can never be neutral, to non-specialists, but also to the differently gifted. If one is gifted in one area but not another, this type of test can never measure their gift.
All intelligence tests require an educational background to answer most of the questions. They also require familiarity with the tests themselves, by taking as MANY as possible, because the ideas and patterns in each test are repeated in other tests too. Most students study extensively before joining colleges requiring taking such tests. Their results are greatly affected by their preparation for the test.
People are different, physically and mentally: short & tall, dark & fair, smart & dumb. That we believe. But it's difficult to believe in the measures by which we judge them now. It could've been easier if we'd got into the brain of every individual to measure his/her smartness directly. But we don't have such technology, yet.
There's a famous story of a Hispanic American who had taken an IQ test when he was in high school; then, based on the test result, he was put with other students into a special class for the "slow learners." Few years later, the same person became an assistant professor at university!
We still give psychologists their due, and we respect IQ tests. SAT (Scholastic Aptitude Test) and other IQ tests are useful in that they show who is eligible and ready for a particular job or education—but NOT the entire mental repertoire of skills someone has, added together. Adding "heterogeneous" entities to each other is just preposterous, and not a "smart" thing.
If A, B and C represent all types of intelligence, then
Intelligence is the governing force of our existence, without which we wouldn't have evolved. Its meaning covers anything, tangible or abstract, following a rule and governed by nature laws: order, harmony, experience, competence, and even beauty and emotions. We talk about smart money, moves, decisions, etc. But smart, clever and dumb are words of obscure immeasurable nature, that we must change our language and put every word, object and human in their right niche, by measuring their potential.
Still, we need to recognize the nature of intelligence before we measure it. Only then can we use and improve it, to make ourselves and others satisfied. Intelligence is the light helping us see things clearly, in a coherent, logical, realistic way. Researchers should continue their work, until someday we will be able to record every movement of the 100 billion neurons our brain has, and every chemical reaction taking place therein. This is not possible at present, for all we have is few intelligence theories and speculations on its meaning, and even fewer facts about it.
Many an ambitious scientist tries to solve this brain mystery by rushing answers without sufficient data—acting similarly to primitive humans who created, believed and lived in myths, whenever they lacked facts. It's the same old human desire to just "believe in something," when ignorance is all there is. Like sitting in a dark room, they are fascinated by the vague mystery-shrouded shapes around them. But why choose darkness when there is a plenty of light (facts) outside?
There is less need in practice for incomplete, let alone incongruent, research results. Examining intelligence nature with the present methods, hypotheses, etc. is only useful in giving "an idea" of what intelligence is. It helps us initially distinguish the gifted or handicapped, the competent or misfit, putting each in the right environment, where they can be happy and useful to others. As for "real intelligence," we still don't know what it is, or an approximation of what it is, because it's more complex than we think it is.