We use whatever concepts we have available to us to understand our experiences. When facing an unfamiliar situation, we intuitively choose a conceptualization that seems to fit in an attempt to make sense of it. And if the first pick fails to give us a handle on the situation, we might “try on” another — if one is available to us.
Having a larger conceptual repertoire gives us more options for understanding. It also raises our expectations with regard to conceptual fit. Perhaps most importantly, the practice of trying out different ways of conceiving subjects us to first-hand experience of contasting experiences of understanding, which produces the insight we conceptualize as pluralism: multiple approaches to understanding always exist, even though it seems only one truth is possible.
Inducing the pluralistic insight, and equipping citizens with a large repertoire of concepts for reaching understandings satisfactory to the greatest possible number of people is the most important function of education in a liberal-democratic society.
Those who make use of a limited set of concepts for understanding the world will be accustomed to making do with semi-adequate understandings. They lack all experience of pluralism: the world they experience is a mysterious and arbitrary world where thinking is barely relevant because it rarely does much good.
One strong argument for public education is ensuring children are taught by teachers who have a reasonably large conceptual repertoire to teach. You cannot give what you do not have. Or to put it differently “if the blind lead the blind, both shall fall into the ditch” — usually the ditch of fundamentalism.