Phenomenalism is the view that physical reality is a phenomenological reward system: a tendency for consciousness to manifest certain phenomenal qualities, given that it manifests certain other phenomenal qualities.
J.S. Mill introduced phenomenalism to the world in 1865. I’ve recently attempted to revive the theory in this book, in which I argue that a radical version of phenomenalism holds the best prospects for reconciling the evidence of introspection with a modern scientific understanding of spacetime. (To get a general feel for my position, see this paper.)
I advocate an especially ambitious phenomenalism, in which spacetime itself, and not just its physical contents, reduces to something purely phenomenological. This assumes that consciousness isn’t in spacetime. I argue that this is a coherent assumption in Chapter 3-5 of Sensorama, as well as the papers you can find here. I also discuss positive reasons to deny consciousness spatiotemporal location here, here, and in Chapter 4 of Sensorama.
Most people reject phenomenalism without really knowing what the theory says. Here are some common misconceptions about it:
Misconception #1: Phenomenalism implies that the world is nothing but a collection of conscious experiences (or combinations of experiences).
The truth: According to a phenomenalist, there are lots of things that are neither experiences nor combinations thereof. A tree, for example, is a tendency for experiences to exist in certain patterns rather than others. Such a tendency is not an experience (or a combination of experiences). (Sense-datum theories do say that physical objects are collections of experiences, or something very much to that effect; but phenomenalism isn’t a sense-datum theory.)
Misconception #2: Phenomenalism implies that physical objects aren’t real.
The truth: Phenomenalists affirm the reality of physical objects; for example, they affirm the reality of trees. They also affirm that physical objects are reducible to something more basic. But reducibility doesn’t entail unreality. (Analogously, most physicalists hold that consciousness is reducible to something more basic, without denying the reality of consciousness.)
Misconception #3: Phenomenalism implies that there are no imperceptible (e.g., submicroscopic) entities.
The truth: A phenomenalist equates imperceptible phenomena with non-obvious (sometimes extremely non-obvious) patterns in experience (or potential experience). Quarks and so forth exist as tendencies for experiences to exist in these non-obvious patterns. (By contrast, perceptible things exist as tendencies for experiences to exist in relatively obvious patterns.) Phenomenalism is therefore compatible with scientific realism.
Misconception #4: Phenomenalism implies that if there were no minds or conscious experiences, there would be no physical world.
The truth: According to phenomenalism, physical things could exist even if there weren’t any minds or experiences, since physical things are tendencies for experiences to exist in certain patterns, and these tendencies could exist even if there didn’t happen to be any minds or experiences to manifest them. (According to canonical idealists, such as Leibniz and Berkeley, there must be minds in order for anything physical to exist, since, according to canonical idealism, the phenomenological reward system is grounded in minds; but phenomenalism is not a canonical idealist theory.)
Misconception #5: Phenomenalism implies that the only things we ever perceive are our own conscious experiences.
The truth: A phenomenalist need not say that we perceive our own conscious experiences at all. We perceive physical objects and events by having experiences that fit into the overall pattern of experiences in certain ways. Phenomenalism is compatible with direct realism.
I am currently writing a second book, tentatively titled Phenomenalism, in which I argue for phenomenalism from a more traditional metaphysical angle, as offering the best answer to the question, “What is a physical thing?”