Mary Midgley (1919-2018) is a philosopher perhaps most well-known for her writing on moral philosophy and rejoinders to Richard Dawkins after his publication of The Selfish Gene. Before her passing in October of 2018, she published What Is Philosophy For? on September 21st. In the book, she discusses ‘intelligence’ and its ‘measurement’ and comes to familiar conclusions.
‘Intelligence’ is not a ‘thing’ like, say, temperature and weight (though it is reified as one). Thermometers measure temperature, and this was verified without relying on the thermometer itself (see Hasok Chang, Inventing Temperature). Temperature can be measured in terms of units like kelvin, celsius, and Fahrenheit. The temperature is the available kinetic energy of heat; ‘thermo’ means heat while ‘meter’ means to measure, so heat is what is being measured with a thermometer.
Scales measure weight. If energy balance is stable, so too will weight be stable. Eat too much or too little, then weight gain or loss will occur. But animals seem to have a body set weight which has been experimentally demonstrated (Leibel, 2008). In any case, what a scale measures is the overall weight of an object which is done by measuring how much force exists between the weighed object and the earth.
The whole concept of ‘intelligence’ is hopelessly unreal.
Prophecies [like those of people who work on AI] treat intelligence as a quantifiable stuff, a standard, unvarying, substance like granulated sugar, a substance found in every kind of cake — a substance which, when poured on in larger quantities, always produces a standard improvement in performance. This mythical way of talking has nothing to do with the way in which cleverness — and thought generally — actually develops among human beings. This imagery is, in fact, about as reasonable as expecting children to grow up into steamrollers on the ground that they are already getting larger and can easily be trained to stamp down gravel on roads. In both cases, there simply is not the kind of continuity that would make any such progress conceivable. (Midgley, 2018: 98)
We recognize the divergence of interests all the time when we are trying to find suitable people for different situations. Thus Bob may be an excellent mathematician but is still a hopeless sailor, while Tim, that impressive navigator, cannot deal with advanced mathematics at all. which of them then should be considered the more intelligent? In real life, we don’t make the mistake of trying to add these people’s gifts up quantitatively to make a single composite genius and then hope to find him. We know that planners wanting to find a leader for their exploring expedition must either choose between these candidates or send both of them. Their peculiar capacities grow out of their special interests in topics, which is not a measurable talent but an integral part of their own character.
In fact, the word ‘intelligence’ does not name a single measurable property, like ‘temperature’ or ‘weight’. It is a general term like ‘usefulness’ or ‘rarity’. And general terms always need a context to give them any detailed application. It makes no more sense to ask whether Newton was more intelligent than Shakespeare than it does to ask if a hammer is more useful than a knife. There can’t be such a thing as an all-purpose intelligence, any more than an all-purpose tool. … Thus the idea of a single scale of cleverness, rising from the normal to beyond the highest known IQ, is simply a misleading myth.
It is unfortunate that we have got so used today to talk of IQs, which suggests that this sort of abstract cleverness does exist. This has happened because we have got used to ‘intelligence tests’ themselves, devices which sort people out into convenient categories for simple purposes, such as admission to schools and hospitals, in a way that seems to quantify their ability. This leads people to think that there is indeed a single quantifiable stuff called intelligence. But, for as long as these tests have been used, it has been clear that this language is too crude even for those simple cases. No sensible person would normally think of relying on it beyond those contexts. Far less can it be extended as a kind of brain-thermometer to use for measuring more complex kinds of ability. The idea of simply increasing intelligence in the abstract — rather than beginning to understand some particular kind of thing better — simply does not make sense. (Midgley, 2018: 100-101)
IQ researchers, though, take IQ to be a measure of a quantitative trait that can be measured in increments—like height, weight, and temperature. “So, in deciding that IQ is a quantitative trait, investigators are making big assumptions about its genetic and environmental background” (Richardson, 2000: 61). But there is no validity to the measure and hence no backing for the claim that it is a quantitative trait and measures what they suppose it does.
Just because we refer to something abstract does not mean that it has a referent in the real world; just because we call something ‘intelligence’ and say that it is tested—however crudely—by IQ tests does not mean that it exists and that the test is measuring it. Thermometers measure temperature; scales measure weight; IQ tests….don’t measure ‘intelligence’ (whatever that is), they measure acculturated knowledge and skills. Howe (1997: 6) writes that psychological test scores are “an indication of how well someone has performed at a number of questions that have been chosen for largely practical reasons” while Richardson (1998: 127) writes that “The most reasonable answer to the question “What is being measured?”, then, is ‘degree of cultural affiliation’: to the culture of test constructors, school teachers and school curricula.”
But the word ‘intelligence’ refers to what? The attempt to measure ‘intelligence’ is a failure as such tests cannot be divorced from their cultural contexts. This won’t stop IQ-ists, though, from claiming that we can rank one’s mind as ‘better’ than another on the basis of IQ test scores—even if they can’t define ‘intelligence’. Midgley’s chapter, while short, gets straight to the point. ‘Intelligence’ is not a ‘thing’ like height, weight, or temperature. Height can be measured by a ruler; weight can be measured by a scale; temperature can be measured by a thermometer. Intelligence? Can’t be measured by an IQ test.