"Intellingence"at best is an assumptive construct—the meaning of the word has never beenclear.（71）There is more agreement on the kinds of behavior referred to by the termthan there is on how to interpret or classify them.But it is generally agreed that a personof high intelligence is one who can grasp ideas readily，make distinctions，reasonlogically，and make ue of verbal and mathematical symbols in solving problems.Anintelligence test is a rough measure of a child's capacity for learning the kinds of thingsrequired in school.It does not measure character，social adjustment，physicalendurance，manual skills，or artistic abilities.It is not supposed to—it was not designed forsuch purposes.（72）To criticise it for such failure is roughly comparable to criticising athermometer for not measuring wind velocity.

The other thing we have to notice is that the assessment of the intelligence of anysubject is essentially a comparative affair.

（73）Now since the assessment of intelligence is a comparative matter we must besure that the scale with which we are comparing our subjects providesa"valid"or"fair"comparison.It is here that some of the difficulties which interest us begin.Anytest performed involves at least three factors:the intention to do one's best，the knowledgerequired for understanding what you have to do，and the intellectual ability to do it.（74）Thefirst two must be equal for all who are being compared，if any comparison in terms ofintelligence is to be made.In school populations in our culture these assumptions can bemade fair and reasonable，and the value of intelligence testing has been provedthoroughly.Its value lies，of course，in its providing a satisfactory basis for prediction.No oneis in the least interested in the marks a little child gets on his test;what we are interested in iswhether we can conclude from his mark on the test that the child will do better or worse thanother children of his age at tasks which we think require"general intelligence".（75）On thewhole such a conclusion can be drawn with a certain degree of confidence，but only ifthe child can be assumed to have had the same attitude towards the test as the otherswith whom he is being compared，and only if he was not punished by lack of relevantinformation which they possessed.