Idealism in philosophy has a quite specific meaning, distinct from the popular usage, which seems to mean something like “optimism” or “being principled”, or “tending towards a utopian view”. Philosophical idealism comes in a variety of flavours. Epistemological idealism is a kind of scepticism or suspension of belief: it is the view that we cannot know mind-independent objects exist, so we must assume objects are mind-dependent until proven otherwise. Ontological idealism is the belief that only mind(s) and mind-dependent objects exist. Semantic idealism is the view that we cannot talk meaningfully of mind-independent objects: our thought and the linguistic expression of our thought are confined within mind-dependency.
Realists in the context of perception are those who hold that mind-independent objects exist and that perception puts us in contact with those objects, either directly or indirectly (i.e. through inference from the data provided in sensory experience). Berkeley as an idealist led an attack against these positions, and Kant developed his own form of idealism, known as transcendental idealism. The debate is very old and goes back to Plato, if not earlier. Plato’s “allegory of the cave” found in his magnum opus, The Republic, is one of the earliest expositions of the view that our reality is in some sense a shadow of another one, the “world of the forms”. Although he later abandoned this view – or so it would appear from his last dialogue – his thesis mutated and spread in the subsequent history of philosophy.
- We have concepts of “universals”, e.g. RED.
- These are properties that multiple objects can have, e.g. a red bus, a red apple, a red ribbon.
- They are also concepts of perfections or standards.
- However, we only ever experience imperfect versions of these universals, e.g. we may find a beautiful woman, but we do not find BEAUTY itself.
- Therefore, experience cannot furnish us with knowledge of universals.
- Therefore, knowledge of universals must be innate; we apply this knowledge in experience to objects in order to make sense of them.
- In order for objects to “partake” of universals, they must have a kind of existence.
- Therefore, there is a “world” where these perfections exist.
- Therefore, there is a more perfect world than the one in which our current sensory experience takes place.
- Since this world is linked to that one, this one must in sense be a “shadow” of it since it is “more perfect”.
Empiricists challenged Plato’s ideas by arguing that we have the means of deriving universals from experience. For example, the concept EQUALITY can be derived by noticing the inequality of, say, two sticks. The concept INEQUALITY is thus derived by abstraction and then converted into EQUALITY through negation. As to the “world” of universals and their “existence”, this is a misunderstanding of the mind, where “relations of ideas”, as Hume called them, are formed, observed, and demonstrated. The comprehension of an item does not entail that this comprehension is anchored in an objective reality upon which it is contingent.