Heterophenomenology is put forth as the alternative to traditional Cartesianphenomenology, which Dennett calls "lone-wolf autophenomenology" to emphasize the fact that traditional phenomenology accepts the subject's self-reports as being authoritative. In contrast, heterophenomenology considers the subjects authoritative only about how things seem to them. It does not dismiss the Cartesian first-person perspective, but rather brackets it so that it can be intersubjectively verified by empirical means, allowing it to be submitted as scientific evidence. The method requires a researcher to listen to the subjects and take what they say seriously, but to also look at everything else available to them, including the subject's bodily responses and environment, evidence provided by relevant neurological or psychological studies, the researcher's memories of their own experiences, and any other scientific data that might help to interpret what the subject has reported. Dennett notes this method is actually the normal way that anyone will choose to investigate aspects of the mind. He writes: "heterophenomenology is nothing new; it is nothing other than the method that has been used by psychophysicists, cognitive psychologists, clinical neuropsychologists, and just about everybody who has ever purported to study human consciousness in a serious, scientific way". The key role of heterophenomenology in Dennett's philosophy of consciousness is that it defines all that can or needs to be known about the mind. For any phenomenological question "why do I experience X", there is a corresponding heterophenomenological question "why does the subject say 'I experience X'". To quote Dennett, "The total set of details of heterophenomenology, plus all the data we can gather about concurrent events in the brains of subjects and in the surrounding environment, comprise the total data set for a theory of human consciousness. It leaves out no objective phenomena and no subjective phenomena of consciousness."
Critique
This comparison by Max Velmans from PhilPapers broadens attitudes to phenomena and noumena: Abstract...
Following an on-line dialogue with Dennett this paper examines the similarities and differences between heterophenomenology and critical phenomenology, two competing accounts of the way that conscious phenomenology should be, and normally is incorporated into psychology and related sciences. Dennett's heterophenomenology includes subjective reports of conscious experiences, but according to Dennett, first person conscious phenomenena in the form of “qualia” such as hardness, redness, itchiness etc. have no real existence. Consequently, subjective reports about such qualia should be understood as prescientific attempts to make sense of brain functioning that can be entirely understood in third person terms. I trace the history of this position in behaviourism and early forms of physicalism and functionalism, and summarise some of the difficulties of this view. Critical phenomenology also includes a conventional, third person, scientific investigation of brain and behaviour that includes subjects’ reports of what they experience. CP is also cautious about the accuracy or completeness of subjective reports. However, unlike HP, CP does not assume that subjects are necessarily deluded about their experiences or doubt that these experiences can have real qualities that can, in principle, be described. Such experienced qualities cannot be exhaustively reduced to third-person accounts of brain and behaviour. CP is also reflexive, in it assumes experimenters to have first-person experiences that they can describe much as their subjects do. And crucially, experimenter's third-person reports of others are based, in the first instance, on their own first-person experiences. CP is commonplace in psychological science, and given that it conforms both to scientific practice and common sense, I argue that there is little to recommend HP other than an attempt to shore up a counterintuitive, reductive philosophy of mind.