Phenomenalism opposes the realism of perception by considering that perception gives us access only to complexes of sensitive data, which do not exist independently of the fact of being or being able to be perceived. The classical origin of phenomenalism dates back to George Berkeley and Work I of his Principles of Human Knowledge (1710). This theory holds that the perceived world consists of data of the senses and that there is nothing other than such a world. We perceive objects that, as far as we know, always depend on the experience we have.
For the phenomenalist, the assertion that perception is able to put us in touch with entities endowed with an autonomous existence – so without relation to us – is in itself contradictory.
Unlike its competing theories, the adverbial theory of perception does not characterize perceptual experience as an act directed to an object but as a way for the perceiving subject to be affected. In this perspective, as well as feeling pain, it is first to be affected painfully, to see a red cube, it is first to be affected “cubically” and “rednessly”.
We speak of adverbial theory to qualify this position because the “internal accusatives” of the verbs of perception are compared to adverbs that modify them. Adverbs are to verbs what adjectives (like “white”) are to nouns (like “bear”). In the expression “The polar bear swims fast”, the adverb “fast” only characterizes swimming, and does not introduce a new object. Similarly, the complement “that the fur of the bear is white” in “I have the visual impression that the coat of the bear is white” modifies the verb “to have the visual impression” without introducing a new distinct object of my visual experience.
The adverbial theory eliminates the content of perception as an object: no experience has an object properly speaking. It thus abolishes the principle of a relation between the subject and the object which seemed to make the specificity of the perceptual experience. The supposed advantage of such an approach is that it avoids the apparently insoluble problem of the nature and location of the contents of perception.