The Child and the Curriculum — John Dewey

Profound differences in theory are never gratuitous or invented. They grow out of conflicting elements in a genuine problem-a problem which is genuine just because the elements, taken as they stand, are conflicting. Any significant problem involves conditions that for the moment contradict each other. Solution comes only by getting away from the meaning of terms that is already fixed upon and coming to see the conditions from another 4 point of view, and hence in a fresh light. But this reconstruction means travail of thought. Easier than thinking with surrender of already formed ideas and detachment from facts already learned is just to stick by what is already said, looking about for something with which to buttress it against attack.