I recently read a passage from Kenneth R. Westphal's Realism, Science, and Pragmatism that read:

Or imagine, following Stout (1938-39), someone in a room which is supported by foundations which no one perceives. What the person perceives--i.e. the room--is actual, but the foundations either do not exist (idealism), or are at best mere unfulfilled possibilities (phenomenalism). But how could something actual be supported by unfulfilled possibilities (or even something non-existent)? It seems that this would lead us to reject many of our ordinary casual and other explanations.

What I don't quite understand is why the idealist/phenomenalist cannot logically infer that since the room he is in is not collapsing, there must be supports underneath the flooring. My question is this: cannot an idealist/phenomenalist have knowledge of unobserved entities through logical inference from his experiences?

  • Our experiences are phenomenal, so logical inferences from phenomenal experiences lead to phenomenal conclusions. To draw conclusions that apply beyond the phenomenal, you need a source of information that is independent from experience.
    – user3017
    Jun 16, 2016 at 1:12
  • Scientists do, why can't everyone else? We had 'knowledge' of chemical atoms long before we could observe them, based entirely upon logical inference from the ways in which they combined.
    – user9166
    Jun 17, 2016 at 21:14

1 Answer 1


To take a page (actually several) from Kant's "Critique of Pure Reason" where he elaborates his theory of what has come to be called "transcendental idealism" (though Kant himself formally rejected idealism as a philosophical perspective) via Edmund Husserl in his ground-breaking "Phenomenology" consider. Performing what Husserl calls the "phenomenological reduction" (the epoche or "standing back") we are basically left with this. The world, as we actually experience it is entirely a construction of our minds based essentially on a synthesis of our sensory input. (Simply to think about this process is to verify it.) In essence (so to speak) we "construct the world from the world" and then, in a sense, project it back out onto the world in the process experiencing our construction as the world. This does not, of course, mean there is no world "out there" (what Kant called the "noumenal world" as opposed to the phenomenal world of our experience). Just that we have and can have no direct experience of it.

Now the really interesting thing here is that physicalism (the more technical term for "materialism") seems to me to be built on top of our subjective construction of the world. This seems to me to put it at a secondary remove from the "real" (noumenal) world and so can hardly form the "basis" of it. Even though Kant and Husserl refrain from doing so (at least explicitly), this fact can be used as a "way back into" idealism. Then read Bernardo Kastrup's "The Idea of the World" (just published and available in Amazon Kindle) and you're there.

  • Which pages from Kant, Husserl and Kastrup most support your answer? A quote from Kastrup might be relevant. This would give the reader a specific place to go for more information. The question also asks whether an idealist/phenomenologist can have knowledge "through logical inference from his experiences"? Apr 25, 2019 at 3:23
  • Husserl's method of "epoche" or "standing back" (aka "the transcendental reduction") to study only the processes of consciousness in themselves is described in detail at the start of both "Cartesian Meditations" and "Phenomenology". So consciousness is all we can really have knowledge of. As to Kastrup, "Matter outside mind is not an empirical fact." (p. 19) Thus no logical inference. This is why I tend to summarize things in my comments and why my basic suggestion is to read authors I cite. Brief quotes with page numbers reveal/support little in my opinion. I confess to being a generalizer. Apr 27, 2019 at 0:14

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