The story of intelligence begins with Plato. In all his writings, he ascribes a very high value to thinking, declaring (through the mouth of Socrates) that the unexamined life is not worth living. Plato emerged from a world steeped in myth and mysticism to claim something new: that the truth about reality could be established through reason, or what we might consider today to be the application of intelligence. This led him to conclude, in The Republic, that the ideal ruler is ‘the philosopher king’, as only a philosopher can work out the proper order of things. And so he launched the idea that the cleverest should rule over the rest – an intellectual meritocracy.
This idea was revolutionary at the time. Athens had already experimented with democracy, the rule of the people – but to count as one of those ‘people’ you just had to be a male citizen, not necessarily intelligent. Elsewhere, the governing classes were made up of inherited elites (aristocracy), or by those who believed they had received divine instruction (theocracy), or simply by the strongest (tyranny).
Source: On the dark history of intelligence as domination | Aeon Essays