Ideas on the Meaning of Idea

September 19, 2025

Thanks to Alissa Simon, HMU Tutor, for today’s post.

On a recent post, I attempted to define idea. Ideas are crucial to the art of learning, yet a precise and singular definition evades me. Clearly, understanding what we’re talking about is never simple. More than a basic definition, though, I want to understand where ideas come from, who uses them, how they continue or evolve, etc.

Using the Syntopicon’s chapter on “Idea,” I organized a very basic chronological timeline of a handful of philosophers who have addressed this question. Since the word idea itself has evolved over time and philosophers continue to debate when to use it correctly, this timeline will be of partial value. For example, some more modern theorists share similar thinking as older ones (Aquinas and Augustine, for example), so a timeline is probably not the best way to organize the material. The debate about what constitutes an idea spans thousands of years and can be slippery indeed! Obviously, there is more to be said and many voices have been left out. It’s a beginning, I suppose. Shaky at best, I offer these notes for what use they might be. And I always encourage further research and debate! Where do you think ideas come from?

Plato:

1] Plato observes two orders of reality: the sensible and the intelligible. There are also two modes of apprehension: sensing and understanding. Idea represents both the intelligible object and the understanding of it.

2] Ideas constitute a realm of intelligible or sensible being and therefore knowledge of reality consists in the apprehension or understanding of ideas.

3] In “Meno,” Socrates says that humans can learn by remembering, as if there is a level of innate (perhaps divine) knowledge already within us. Ideas, then, are independent in origin

Aristotle:

Ideas have no being except as perceptions or thoughts. They are the instruments whereby reality is known.

Lucretius:

Idea does not include external perceptions, but only products of the mind through acts of memory or imagination.

Plotinus:

Idealism signifies a superior reality of the ideal. Ideas exist in the mind and participate with the divine. Things can be materially real, but they exist in a profoundly different way than ideas.

Augustine:

Ideas are independent in origin, neither material nor physical. They participate with a higher mind.

Aquinas:

1] Concepts are the means of knowledge, not the objects of knowledge. “A concept is not what is actually understood, but that by which the intellect understands.”

2] Adler summarizes Aquinas: “The ideas are concepts whereby real things are understood are sometimes called ‘first intentions’ of the mind. The ideas whereby we understand these ideas or first intentions are called the mind’s ‘second intentions.’ An idea is always a mental intention, an awareness or representation, never an independent reality for the mind to know.”

3] In agreement with Augustine, Aquinas believes ideas originate in a pure mind, to which the human intellect connects, but cannot fully comprehends. He quotes Augustine who says that divine ideas are the perfect, immutable, original forms of things.

Descartes:

1] Ideas exist in the human mind, concepts cannot exist apart from the mind.

2] He divides ideas into innate and adventitious. Innate originate within the self. Adventitious come from outside, like feeling heat from the sun. The ideas that we invent or form are constructions of the imagination.

3] Intuition leads one to understand ideas. “…the unclouded and attentive mind…springs forth from the light of reason alone.”

4] Ideas stem from a thinking substance (not extended matter or bodily substance).

Locke:

1] Though he claims that the word idea is overused, he prefers idea because it best serves “to stand for whatsoever is the object of the understanding when a man thinks.”

2] Locke differentiates between ideas of reflection and ideas of sensation (sort of parallel to medieval thinkers).

3] He uses the word idea for both the original elements of sense-experience and for all derivatives from it.

Berkeley:

Ideas or objects of mind cannot exist without the perceiving mind and their cause is not the thing itself nor the mind, but some other will or spirit which produces them.

Hume:

1] Adler summarizes: “Ideas as well as impressions are involved in our knowledge of matters of fact, but relations between ideas may also be objects of knowledge, as in the sciences of geometry, algebra, arithmetic.”

2] Hume separates experience into degrees. The more lively are named thoughts or ideas. The more impactful he calls impressions. Impressions comes from intensity of perceptions such as “when we hear, see, feel, love, hate, desire, or will.”

Kant:

Adler offers this description of Kant’s explanation of idea: Kant “proposes a graduated list of terms…. He begins with perception, which he divides into sensation and cognition, according as it is subjective or objective. A cognition… ‘is either an intuition or a conception,’ according as it has either an immediate or mediate relation to its object. Dividing conceptions into the empirical and the pure, Kant finally reaches the term idea as one subdivision of pure conceptions. If the pure conception ‘has its origin in the understanding alone, and is not the conception of a pure sensuous image,’ it is a notio or notion; and ‘a conception formed from notions, which transcends the possibility of experience, is an idea, or a conception of reason.’”

William James:

James agrees with Aristotle that ideas are concepts, but not sensations or perceptions. This doesn’t mean that concepts require an outside mover, “both concept and percept belong to the single ‘stream of thought’ and are ‘states of consciousness.”

Photo credit: Shutterstock/ nature photos