The IQ test is multivariate and has a number of axes which are not boolean like your teakettle test is.
Intelligence is not a property like physical attributes. It is fuzzy and has a lot of aspects. Some forms of intelligence aren't tested with the IQ test (unless somehow done recently), the primary one that comes to mind is social nous.
The psychology of intelligence is a complex, varied, and interesting field, and those who naysay "you can't study / define / measure intelligence!" are submitting to pop science just like "take this pop IQ quiz!". I've lost track of it over the years, but there are reams of research into intelligence, what it is, how it's defined, how tests do or don't reflect intelligence.
The IQ test covers a lot of different aspects of intelligence - it gives a fairly comprehensive representation of many aspects, and hence why it's a decent measure of intelligence. It's not a cut-and-dried thermometer measure, yes - but this is because psychology never works that way, something that engineers have trouble getting their heads around. Nothing in psychology is concrete, and if you're going to dismiss based on not being 100% precise, well, then psychology can't exist, nor can any of the fields based from it (like sociology, criminology, so on and so forth)
Intelligence is not a property like physical attributes. It is fuzzy and has a lot of aspects. Some forms of intelligence aren't tested with the IQ test (unless somehow done recently), the primary one that comes to mind is social nous.
The psychology of intelligence is a complex, varied, and interesting field, and those who naysay "you can't study / define / measure intelligence!" are submitting to pop science just like "take this pop IQ quiz!". I've lost track of it over the years, but there are reams of research into intelligence, what it is, how it's defined, how tests do or don't reflect intelligence.
The IQ test covers a lot of different aspects of intelligence - it gives a fairly comprehensive representation of many aspects, and hence why it's a decent measure of intelligence. It's not a cut-and-dried thermometer measure, yes - but this is because psychology never works that way, something that engineers have trouble getting their heads around. Nothing in psychology is concrete, and if you're going to dismiss based on not being 100% precise, well, then psychology can't exist, nor can any of the fields based from it (like sociology, criminology, so on and so forth)