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Roderick Chisholm criticized the logical positivist version of phenomenalism in 1948. C.I. Lewis had previously suggested that the physical claim "There is a doorknob in front of me" necessarily entails the sensory conditional "If I should seem to see a doorknob and if I should seem to myself to be initiating a grasping motion, then in all probability the sensation of contacting a doorknob should follow". Chisholm objected that the statement "There is a doorknob..." does not entail the counterfactual statement, for if it were to do so, then it must do so without regard to the truth or falsity of any other statement; but suppose the following statement was true: "I am paralyzed from the neck down and experience hallucinations such that I seem to see myself moving toward the door". If this were true, Chisholm objected, then there could be a doorknob in front of me, I could seem to myself to see a doorknob, and I could seem to myself to be performing the correct sort of grasping motion, but with absolutely no chance of having a sensation of contacting the doorknob. Likewise, he objected that the statement that "The only book in front of me is red" does not entail the sensory statement "Redness would probably appear to me were I to seem to myself to see a book", because redness is not likely to appear under a blue light-bulb. Some[who?] have tried to avoid this problem by extending the conditions in the analysandum: instead of "There is a doorknob in front of me" one could have it that "There is a doorknob, and I am not paralyzed, etc." In response, Chisholm objects that if one complicates the analysandum, one must also complicate the analysans; in this particular case, that one must analyse in purely sensory terms what it means not to be paralyzed and so on, with respect to which the same problems would arise leading to an infinite regress.

20th century American philosopher Arthur Danto asserted that "a phenomenalist, believ[es] that whatever is finally meaningful can be expressed in terms of our own [sense] experience.". He claimed that "The phenomenalist really is committed to the most radical kind of empiricism: For him reference to objects is always finally a reference to sense-experience ... ." To the phenomenalist, objects of any kind must be related to experience. "John Stuart Mill once spoke of physical objects as but the 'permanent possibility of experience' and this, by and large, is what the phenomenalist exploits: All we can mean, in talking about physical objects — or nonphysical objects, if there are any — is what experiences we would have in dealing with them ... ." However, phenomenalism is based on mental operations. These operations, themselves, are not known from sense experience. Such non-empirical, non-sensual operations are the "...nonempirical matters of space, time, and continuity that empiricism in all its forms and despite its structures seems to require ... ." Logical positivism, a movement begun as a small circle which grew around the philosopher Moritz Schlick in Vienna, inspired many philosophers in the English speaking world from the 1930s through the 1950s. Important influences on their brand of empiricism included Ernst Mach — himself holding the Chair of Inductive Sciences at the University of Vienna, a position Schlick would later hold — and the Cambridge philosopher Bertrand Russell. The idea of the logical positivists, such as A.J. Ayer and Rudolf Carnap, was to formulate the doctrine of phenomenalism in linguistic terms, so as to define references to such entities as physical objects in the external world out of existence. Sentences which contained terms such as "table" were to be translated into sentences which referred exclusively to either actual or possible sensory experiences.

In the late 19th century, an even more extreme form of phenomenalism was formulated by Ernst Mach, later developed and refined by Russell, Ayer and the logical positivists. Mach rejected the existence of God and also denied that phenomena were data experienced by the mind or consciousness of subjects. Instead, Mach held sensory phenomena to be "pure data" whose existence was to be considered anterior to any arbitrary distinction between mental and physical categories of phenomena. In this way, it was Mach who formulated the key thesis of phenomenalism, which separates it from bundle theories of objects: objects are logical constructions out of sense-data or ideas; whereas according to bundle theories, objects are made up of sets, or bundles, of actual ideas or perceptions. That is, according to bundle theory, to say that the pear before me exists is simply to say that certain properties (greenness, hardness, etc.) are being perceived at this moment. When these characteristics are no longer perceived or experienced by anyone, then the object (pear, in this case) no longer exists. Phenomenalism as formulated by Mach, in contrast, is the view that objects are logical constructions out of perceptual properties. On this view, to say there is a table in the other room when there is no one in that room to perceive it, is to say that if there were someone in that room, then that person would perceive the table. It is not the actual perception that counts, but the conditional possibility of perceiving.

Phenomenalism is a radical form of empiricism and, hence, its roots as an ontological view of the nature of existence can be traced back to George Berkeley and his subjective idealism, which David Hume further elaborated. John Stuart Mill had a theory of perception which is commonly referred to as classical phenomenalism. This differs from Berkeley's idealism in its account of how objects continue to exist when no one is perceiving them. Berkeley claimed that an omniscient God perceived all objects and that this was what kept them in existence, whereas Mill claimed that permanent possibilities of experience were sufficient for an object's existence. These permanent possibilities could be analysed into counterfactual conditionals, such as "if I were to have y-type sensations, then I would also have x-type sensations".

Phenomenalism is the view that physical objects do not exist as things in themselves but only as perceptual phenomena or sensory stimuli (e.g. redness, hardness, softness, sweetness, etc.) situated in time and in space. In particular, phenomenalism reduces talk about physical objects in the external world to talk about bundles of sense-data.

Another common[who?] objection to phenomenalism is that in the process of eliminating material objects from language and replacing them with hypothetical propositions about observers and experiences, it seems to commit us to the existence of a new class of ontological object altogether: the sensibilia or sense-data which can exist independently of experience. Indeed, sense-data have been dismissed by some philosophers of mind, such as Donald Davidson, as mythological entities that are more troublesome than the entities that they were intended to replace.