Philosophically, idealism is the epistemology according to which reality is constructed in our minds; that is, it does not exist outside our consciousness or at least it cannot be immediately and directly experienced and understood. In social sciences, idealism usually refers to the insight that our perception of reality is socially constructed: it follows social conventions, passes through mental filters, and is mediated by the abstract categories and ideas existing in our minds. Idealism is the opposite of materialism—the assumption that all phenomena, including mental processes and the human consciousness, are material in nature and follow physical or natural laws—but can just as well be set apart from realism—the belief that reality exists independently of human perceptions and concepts.

In political discourse, idealism connotes policies based ...