According to the Peircean theory of cognition, even sense perception is a matter of hypothetical inference. Physiologically, perception is the response of a nervous system, in some specific context, to the arrival of a stimulus to its sensorium, such as a barrage of photons upon the retina. In cognitive terms, ‘each sense is an abstracting mechanism’ (Peirce, EP1:50), and consciously experienced sensations or feelings
are in themselves simple, or more so than the sensations which give rise to them. Accordingly, a sensation is a simple predicate taken in place of a complex predicate; in other words, it fulfills the function of an hypothesis.
EP1:42
Cognition then is a continuous inferential (i.e. semiotic) process whose products range all the way from involuntary perceptual judgments to complex theoretical contructs. These products include sensations and feelings which may be recognized as qualities of the objects perceived or imagined.
Some are inclined to doubt that these qualities have any reality beyond our awareness of them. In the fourth of his 1903 Harvard Lectures, Peirce argued by analogy that ‘qualities of feeling’ – the qualities we recognize in our perceptual judgments, as when we perceive a blue color – are elements of the real universe. They are real because they are beyond our control, i.e. not subject to logical criticism.
the distinction of logical goodness and badness must begin where control of the processes of cognition begins; and any object that antecedes the distinction, if it has to be named either good or bad, must be named good. For since no fault can be found with it, it must be taken at its own valuation. Goodness is a colorless quality, a mere absence of badness. Before our parents had eaten of the fruit of the tree of knowledge of good and evil, of course, they were innocent.
EP2:191
There is no way to find fault with a percept, and perceptual judgments are likewise innocent. Any criticism of it ‘would be limited to performing it again and seeing whether with closer attention we get the same result’ – but strictly speaking, it can’t be performed again on the same percept, for as Heraclitus put it, one cannot step twice into the same river. Its flow is the essence of the stream of consciousness.
In short, the Immediate (and therefore in itself unsusceptible of mediation—the Unanalyzable, the Inexplicable, the Unintellectual) runs in a continuous stream through our lives; it is the sum total of consciousness, whose mediation, which is the continuity of it, is brought about by a real effective force behind consciousness.
Thus, we have in thought three elements: first, the representative function which makes it a representation; second, the pure denotative application, or real connection, which brings one thought into relation with another; and third, the material quality, or how it feels, which gives thought its quality.EP1:42
These are essentially the same three elements that Peirce would later call Thirdness, Secondness and Firstness respectively. By 1903, Peirce was ready to affirm the reality of all three: being the elements of thought and reasoning, they are also really elements of any cognizable universe; ‘every scientific explanation of a natural phenomenon is a hypothesis that there is something in nature to which the human reason is analogous’ (EP2:193). The immediacy and spontaneity of Firstness has its part to play in hypothetical models of nature just as forces and regularities do. Therefore, says Peirce,
if you ask me what part Qualities can play in the economy of the universe, I shall reply that the universe is a vast representamen, a great symbol of God’s purpose, working out its conclusions in living realities. Now every symbol must have, organically attached to it, its Indices of Reactions and its Icons of Qualities; and such part as these reactions and these qualities play in an argument, that they of course play in the universe, that Universe being precisely an argument. In the little bit that you or I can make out of this huge demonstration, our perceptual judgments are the premisses for us and these perceptual judgments have icons as their predicates, in which icons Qualities are immediately presented. But what is first for us is not first in nature. The premisses of Nature’s own process are all the independent uncaused elements of facts that go to make up the variety of nature which the necessitarian supposes to have been all in existence from the foundation of the world, but which the Tychist supposes are continually receiving new accretions. These premisses of nature, however, though they are not the perceptual facts that are premisses to us, nevertheless must resemble them in being premisses. We can only imagine what they are by comparing them with the premisses for us. As premisses they must involve Qualities.
Now as to their function in the economy of the Universe,—the Universe as an argument is necessarily a great work of art, a great poem,—for every fine argument is a poem and a symphony,—just as every true poem is a sound argument. But let us compare it rather with a painting,—with an impressionist seashore piece,—then every Quality in a Premiss is one of the elementary colored particles of the Painting; they are all meant to go together to make up the intended Quality that belongs to the whole as whole. That total effect is beyond our ken; but we can appreciate in some measure the resultant Quality of parts of the whole,—which Qualities result from the combinations of elementary Qualities that belong to the premisses.EP2:193-4
So although ‘what is first for us is not first in nature,’ the ‘Immediate’ and ‘Inexplicable’ which ‘runs in a continuous stream through our lives’ shares a Firstness with ‘the independent uncaused elements of facts that go to make up the variety of nature.’