The traditional epiphenomenalist claim is that the mental properties are simply a by-product of neurophysiological events and so have no causal efficacy over the physical world. This obviously implies that all activities of the mind, like thoughts, are a result of purely physical events. There is a problem though; consider a thought that says "I have absolute certainty that felt-states exist." But for this to be true, somehow the "feltness" of brain activity must have some feedback on the brain so that the brain could even form such a thought in the first place.

By what mechanism could this be the case? How does the brain know (with certainty) about qualia and consciousness according to the epiphenomenalist?

  • Do brains know? I thought knowledge applied to a state of the conscious mind.
    – J D
    Jan 17, 2020 at 19:47
  • @JD Well, "know" in the sense of contains information of felt-states.
    – natojato
    Jan 17, 2020 at 20:29
  • And brains are physical containers?
    – J D
    Jan 18, 2020 at 2:47
  • Being epiphenomenal does not prevent "felt-states" (or anything else) from existing, just like reflections in the mirror also do exist. "Feltness" may well be a by-product of the same neurophysiology. And "I have absolute certainty that X" does not tell us whether X is true one way or the other.
    – Conifold
    Jan 20, 2020 at 4:46
  • I don't believe there's any way to make sense of the speculations of the epiphenomenalists, partly for the reasons you give. At any rate, I cannot do so. ,
    – user20253
    Jan 20, 2020 at 10:27

2 Answers 2


Epiphenominalists are often trying to accommodate scientific facts without discarding the reality of the mind. Various things happen that do not accord with the folk-psychology that all immediate experience must be shaped the way we generally discuss it in words. Instead, it is partly conditioned by the existence of words, and their purpose.

(The entire motivation comes from looking at the proper boundaries between different sciences. It makes as much sense to discuss the mind in terms of brain circuitry as it would to discuss baking in terms of the shapes of orbitals making up chemical bonds. It is two layers of epiphenomenon away from what is reasonably tractable -- it skips over both behavioral conditioning caused by and through language and social construction by acculturation. So arguments that make that leap and put the two side-by-side end up being misleading or vacuuous. This includes philosophical inquiries about what things like qualia "are, physically".)

From an evolutionary point of view, feelings are about their survival consequences, not about their causes. In particular, we see in psychotherapeutic contexts that feelings and impressions do not arise immediately and unconditionally at the point where the events that cause them, happen. That would mean that the brain feels what it has evolved to feel. It does not actually feel its own state. It feels the emotional or informational tendencies that those states predict should be most efficacious given its evolution. The feelings are epiphenomena and not an expression of a given state of current reality within the brain or within the environment at all. It is not unreasonable to generalize that observation to all "felt states".

The behavior of people raised in deep isolation, and the memories of people newly given language and social exposure later in life indicate that beforehand, they do not experience ideas in the same way. For instance, navigation through space, something we think of deeply intuitive and 'built-in', improves when people are first given words for directions and kinds of movement long after infancy. This suggests that ideas, even ones as basic as our sense of geometry, which we often use without consciously thinking in words, are deeply related to the ability to express them to other people.

Even things we do not think of as stories may take the form of the preparation of social narrative, a draft of a description of our state, (if not in language, then in some related social product we could deliver or enact if asked,) as in Dennett's "multiple drafts model". Taking this to its logical extreme, if increasing expressive options makes this much difference, without other people and their social expectations, encountered early in life, it becomes doubtful we would experience the "having of ideas" at all. So the whole notion of thought that is built on describing it in terms of ideas cannot be taken for granted as natural. But we automatically do that when we assume the reality or nature of qualia and consciousness -- because those terms are conditioned on self-observation in terms of ideas. If those are created by the social contract, we do not need a naturalistic "brain-level" description of them. And giving one would be inappropriate.

The insights of modern perceptual experiments on reaction timing suggest that qualia and the experience of time passing take time to appear in the mind. So they are most likely not fundamental, but derived from our reasoning process. This means the brain does not know about qualia, it knows about the labelling of experiences. It does not know about consciousness, it knows about extremely-short-term memory. We invent these more abstract terms, but what we can really identify of them always reduces to something less esoteric. What we can identify of consciousness is the stream of language and experience that marks the passage of time. What we can identify of qualia are memories of images or sensory traces and qualities we associate with them. Once you step away from the forced concept into the behavioral contents, the mystery disappears.

All of this paints a picture of 'immediate experience' that is much less immediate and is instead a learned game. You can have certainty that these things exist in the same way you can enumerate the qualities of a unicorn. You can know the socially acceptable behavioral correlates. The actual experience is just a finely tuned method of evoking those correlates on cue.

So the answer is that we cannot explain this knowledge because there is no such knowledge. There is training to conceptualize things in this manner to improve our social interactions. They are not information, they are learned habits of reference, that does not mean they actually refer to anything.

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    I have thought it best to delete the series of exchanges that followed this answer. I can't see that users would find much light in it.
    – Geoffrey Thomas
    Jan 20, 2020 at 13:38

consider a thought that says "I have absolute certainty that felt-states exist." But for this to be true, somehow the "feltness" of brain activity must have some feedback on the brain so that the brain could even form such a thought in the first place.

By what mechanism could this be the case? How does the brain know (with certainty) about qualia and consciousness according to the epiphenomenalist?

The brain state includes:

  1. structures, X, that correspond to qualia.
  2. separate structures that correspond to meta-claims about the qualia experienced. Let us look at the structure corresponding to the claim "Meta(X)" where X is a quale. Meta(X) means the meta-statement, "I am currently feeling X," and is another physical structure distinct from the physical structure of X itself.

The mind state includes:

  1. For each qualia-correspondent brain-structure X, the subjective quale MentalEvent(X)
  2. For each meta-claim-correspondent brain-structure Meta(X), the mental event of making the judgment "I am currently feeling X." This event shall be called MentalEvent(Meta(X)).

This function MentalEvent takes us from properties of the brain state, to properties of the mind state.

The diagram looks like this:

Brain state properties                    Mental state properties
    X    ---------------------------------->  MentalEvent(X)
    | (causal relationship)
  Meta(X) --------------------------------->  MentalEvent(Meta(X))

The arrow drawn from X to Meta(X) indicates a physical, causal relationship, whereby a person obtains the brain-structure Meta(X), as a causal result of initially having the brain-structure X. This is reflected in mental events, but there is no interaction from mental events back to physical events.

  • Please say more about a difference between physical causation (vertical arrow) and epiphenomenal causation (horizontal arrow). Is it true to say that the first is a "two-argument" function: Meta(X)=f(X, X'), where X' is another physical structure, different from X, and X' undergo a coercion from X. Whereas the second causation is "one-argument": MentalEvent(X)=f(X), so that X just generates MentalEvent, simply maps itself in consciousness.
    – ttnphns
    Feb 14, 2021 at 10:05
  • @ttnphns It's not clear to me what you mean by f(X, X'). Meta(X) is already a physical brain structure different from X, that is caused in part by X, so what do you want X' for, and what is f? If f is meant to represent the causal dependence, that's too simplistic - fully describing the causal dependence can't be done just by saying one brain structure is a function of the other. There are many other unstated variables involved that influence whether and when the Meta(X) structure arises.
    – causative
    Feb 14, 2021 at 10:16
  • Sure, "many other unstated variables" etc. I was asking to elucidate me the difference between a physical causation and a epiphenomenal production.
    – ttnphns
    Feb 14, 2021 at 10:26
  • @ttnphns yes, there's certainly a difference. MentalEvent(X) is directly a function of X, and Meta(X) is only causally related to X, and we may sometimes have X without having Meta(X). Whether Meta(X) arises after X arises depends on what the person is paying attention to, what other facts they are considering, and their general state of mind (or "state of brain").
    – causative
    Feb 14, 2021 at 19:23

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