Idea

An idea (from the Greek *idea*, meaning "a form" or "a pattern") is what comes from thinking. While the word is common in everyday speech, in philosophy ideas can also be mental images that represent objects. Many thinkers have treated ideas as a basic category of existence. The ability to form and grasp ideas is seen as a key trait that defines human beings.

Ideas can pop up reflexively or spontaneously, even without deep thought—like when we talk about the idea of a person or a place. A new or original idea often sparks innovation. Our actions are based on beliefs, and beliefs are patterns or organized sets of ideas.

**Etymology** The word comes from Greek *idea*, meaning "form" or "pattern," from the root *idein*, "to see."

**History** Plato opened the debate over the nature of ideas. His theory of forms, developed across many dialogues, gave a new meaning to the Greek word for things that are "seen," focusing on elements of perception that have no material or objective reference. As this view spread, "idea" took on its modern sense. In Book V of the *Republic*, Plato defines philosophy as the love of this formal (not visual) way of seeing. He argued that perceived but immaterial objects form a realm of eternal forms or ideas from which the material world comes. Aristotle disagreed, saying ideas in the mind are composites of remembered observations. Though it is anachronistic, we can call Plato an idealist and Aristotle an empiricist. This clash between empiricism and idealism has driven the debate over ideas ever since, and it remains unresolved. Today it appears in the split between analytic and continental philosophy, with the gap between classical physics and quantum mechanics as a rough analogy.

**Philosophy**

**Plato** Plato was among the first to discuss ideas in detail (though his Greek *idea* differs from our modern term). In dialogues like the *Phaedo*, *Symposium*, *Republic*, and *Timaeus*, he argued that ideas exist independently of anyone thinking them. They separate mere opinion from knowledge: material things are temporary and can have opposite properties, but ideas are unchanging and exactly what they are. So material things can only be objects of opinion; real knowledge is only of unchanging ideas. Ideas also serve as universals. In the *Republic* he writes: "We both assert that there are many fair things, many good things, and so on... And we also assert that there is a fair itself, a good itself... and we refer to them as one idea of each... the former are seen, but not intellected, while the ideas are intellected but not seen."

**René Descartes** Descartes often used "idea" to mean an image or representation, usually in the mind, following common speech. In his *Meditations on First Philosophy* he says, "Some of my thoughts are like images of things, and it is to these alone that the name 'idea' properly belongs." He sometimes thought ideas were innate, and his use of the term diverged from earlier scholastic usage. He gave several different definitions, used the word for at least six kinds of entities, and divided ideas inconsistently. For him, knowledge took the form of ideas, and philosophy was about examining these entities.

**John Locke** Locke’s use of "idea" contrasts sharply with Plato’s. In his *Essay Concerning Human Understanding*, he defines idea as "that term which... stands for whatsoever is the object of the understanding when a man thinks... I have used it to express whatever is meant by phantasm, notion, species, or whatever it is which the mind can be employed about in thinking." He saw his essay as necessary to examine our own abilities and see what our understandings could or could not handle. Thinkers who followed his approach include Hume, Kant, Schopenhauer, Russell, Wittgenstein, and Popper. Locke always trusted common sense, avoided extremes, and stuck to plain facts, favoring ideas that seemed "good."