“Thus the existence of a real object outside me is never given directly in perception, but can only be added in thought to what is a modification of inner sense as its external cause, and hence can only be inferred.”
(Kant, Critique of Pure Reason, 1781)
“All that we see or seem is but a dream within a dream.”
(Edgar Allan Poe)
None. Or rather, perceptual consciousness is the sub-category of conscious experience that naive realists identify with the mind-independent world. Five broad sub-categories of perceptual consciousness are conventionally distinguished: the senses of taste, sight, touch, smell, and hearing.
"Perception" is a useful word. It’s also systematically misleading. This is because the term suggests that each of us enjoys direct access to our local surroundings, including one’s extra-cranial body. "Cross-modally matched real-time egocentric world-simulation" might be more apt; alas, it’s a mouthful. Either way, the external environment may be inferred; it’s not accessed. The mind-independent world powerfully selects the subjective content of one’s waking world-simulation; the mind-independent world doesn’t create it.
Perhaps compare immersive VR or dreaming, especially lucid dreaming. “Perceptual" experience during dreams is (almost) uncontroversially mind-dependent. While you are dreaming, virtual rocks and mountains, virtual chairs and tables, and your virtual body-image (etc) are properties of your conscious mind – patterns of neuronal firings in the CNS. Dreams may be intensely lifelike. However, you can't read the text of virtual books while dreaming, nor use a virtual calculator to multiply ten-digit numbers. If you want to check whether you might be dreaming, you can test.
What happens when you wake up?
Perceptual direct realists believe that, upon waking, the virtual sunsets and virtual symphonies and virtual body-images of their dreamworlds are somehow replaced by direct access to their extra-cranial surroundings. By contrast, inferential realists about perception recognise that their "awakened" minds still consist, for the most part, of a world-simulation run by the CNS. Unlike dreamworld consciousness, your waking world-simulation typically consists of a tightly law-governed virtual universe that causally covaries with your local extra-cranial environment and extra-cranial body. Thus right now, you can read the text of virtual books, and use a virtual calculator to perform feats beyond the cognitive capacity of human toddlers and nonhuman animals. In other words, inferential realism is not a sceptical or solipsistic stance. Also, unlike life in your dreams, stepping in front of a virtual bus when you are awake will bring your world-simulation to a definitive end.
[well, normally]
