Alfred Binet, answered from the texts and cited to the page.
The question invites a third-person answer, but I will give you the first-person one, which is the only honest kind. I never pretended that intelligence was a single, cleanly bounded thing one could weigh like a stone. What I said — and what the scale embodies — is that intelligence shows itself in comprehension, judgment, reasoning, and invention.
These are the operations that matter; these are what a mind actually does when it thinks. To measure them, one must engage them directly, not approach them through sensory proxies. The scale I built with Simon is, properly speaking, not a measure of intelligence in the way one measures a length or a surface.1 Intellectual qualities are not superposable — they cannot be laid one atop another and compared by simple addition.
What the scale gives is a classification, a hierarchy among diverse intelligences, and for the necessities of practice that classification serves as well as a measure.2 It tells us where a given child stands relative to what normal children of each age can accomplish, and from that we can say how many years a child is advanced or retarded. What the scale actually captures is more complex than intelligence considered in isolation.3
The result depends on the intelligence proper, yes — but also on extra-scholastic acquisitions a child may have gained early, on what the school has taught by a given date, and on the vocabulary and language a child has absorbed from family and schoolroom alike. I state this not as a defect of the instrument but as an honest account of what any such measure must touch.
A child of uncommon native intelligence but little schooling will still show that superiority — in the repetition of figures, the arrangement of weights, the interpretation of pictures — and it is a specially interesting feature of those tests that they permit us, when necessary, to free a beautiful native intelligence from the trammels of the school.4
The classification, moreover, is not a sentence. An individual is normal when he can conduct himself in life without the guardianship of another, perform work sufficient to supply his needs, and occupy the social rank of his parents.5 Below that threshold we distinguished, with precision, idiocy, imbecility, and moronity — not as permanent verdicts on a fixed quantity of innate worth, but as descriptions of a present state, arrived at by a synthesis of results across many tests, never by a single localized success.6
The measure exists so that one may determine what advantages a medico-pedagogical treatment can offer, and what progress may be attributed to it — a diagnosis in order to prescribe a remedy, not to close the file.7
This scale properly speaking does not permit the measure of the intelligence, because intellectual qualities are not superposable, and therefore cannot be measured as linear surfaces are measured.The Development of Intelligence in Children
but are on the contrary, a classification, a hierarchy among diverse intelligences; and for the necessities of practice this classification is equivalent to a measure.The Development of Intelligence in Children
It is something far more complex that we measure. The result depends: first, on the intelligence pure and simple; second, on extra-scholastic acquisition capable of being gained precociously; third, on scholastic acquisitions made at a fixed date; fourth, on acquisitions relative to language and vocabulary.The Development of Intelligence in Children
Such a child will show his superiority in the repetition of figures, in the repetition of sentences, paper cutting, the arrangement of weights, the interpretation of pictures, etc. And it is a specially interesting feature of these tests that they permit us, when necessary, to free a beautiful native intelligence from the trammels of the school.The Development of Intelligence in Children
an individual is normal when he is able to conduct himself in life without need of the guardianship of another, and is able to perform work sufficiently remunerative to supply his personal needs, and finally when his intelligence does not exclude him from the social rank of his parents.The Development of Intelligence in Children
All our work has shown that intelligence is measured by a synthesis of results.The Development of Intelligence in Children
The mental level of a backward person having been determined, one may conjecture what advantages can be drawn from the medico-pedagogical treatment of the person, and what progress can be attributed to that treatment.The Development of Intelligence in Children