The term "Idealism" came into vogue roughly during the time of Kant (though it was used earlier by others, such as Leibniz) to label one of two trends that had emerged in reaction to Cartesian philosophy.

Descartes had argued that there were two basic yet separate substances in the universe: Extension (the material world of things in space) and Thought (the world of mind and ideas). Subsequently opposing camps took one or the other substance as their metaphysical foundation, treating it as primary while reducing the remaining substance to derivative status.

Materialists argued that only matter was ultimately real, so that thought and consciousness derived from physical entities (chemistry, brain states, etc.). Idealists countered that the mind and its ideas were ultimately real, and that the physical world derived from mind (e.g., the mind of God, Berkeley's esse est percipi, or from ideal prototypes, etc.) Materialists gravitated toward mechanical, physical explanations for why and how things existed, while Idealists tended to look for purposes - moral as well as rational - to explain existence. Idealism meant "idea-ism," frequently in the sense Plato's notion of "ideas" (eidos) was understood at the time, namely ideal types that transcended the physical, sensory world and provided the form (eidos) that gave matter meaning and purpose. As materialism, buttressed by advances in materialistic science, gained wider acceptance, those inclined toward spiritual and theological aims turned increasingly toward idealism as a countermeasure. Before long there were many types of materialism and idealism.

Idealism, in its broadest sense, came to encompass everything that was not materialism, which included so many different types of positions that the term lost any hope of univocality [i.e. a single meaning]. Most forms of theistic and theological thought were, by this definition, types of idealism, even if they accepted matter as real, since they also asserted something as more real than matter, either as the creator of matter (in monotheism) or as the reality behind matter (in pantheism). Extreme empiricists who only accepted their own experience and sensations as real were also idealists. Thus the term "idealism" united monotheists, pantheists and atheists. At one extreme were various forms of metaphysical idealism which posited a mind (or minds) as the only ultimate reality. The physical world was either an unreal illusion or not as real as the mind that created it. To avoid solipsism (which is a subjectivized version of metaphysical idealism) metaphysical idealists posited an overarching mind that envisions and creates the universe.

A more limited type of idealism is epistemological idealism, which argues that since knowledge of the world only exists in the mental realm, we cannot know actual physical objects as they truly are, but only as they appear in our mental representations of them. Epistemological idealists could be ontological materialists, accepting that matter exists substantially; they could even accept that mental states derived at least in part from material processes. What they denied was that matter could be known in itself directly, without the mediation of mental representations. Though unknowable in itself, matter's existence and properties could be known through inference based on certain consistencies in the way material things are represented in perception.

Transcendental idealism contends that not only matter but also the self remains transcendental in an act of cognition. Kant and Husserl, who were both transcendental idealists, defined "transcendental" as "that which constitutes experience but is not itself given in experience." A mundane example would be the eye, which is the condition for seeing even though the eye does not see itself. By applying vision and drawing inferences from it, one can come to know the role eyes play in seeing, even though one never sees one's own eyes. Similarly, 'things in themselves' and the 'transcendental self' could be known if the proper methods were applied for uncovering the conditions that constitute experience, even though such conditions do not themselves appear in experience. — Dan Lusthaus

So what really is the difference between the two views? — khaled

A materialist believes that there are material things with no minds — Kenosha Kid

This in turn allows for a kind of coincidence of human mind and human matter, such that we can argue for the primacy of the mental — Kenosha Kid

There is physical stuff, and we interpret said physical stuff, and there is no point at which we can be 100% sure of our interpretations. — khaled

A materialist believes that there are material things with no minds
— Kenosha Kid

I can take this two ways — khaled

Again, I think if you say that there are 2 different kinds of stuff, mental stuff and physical stuff, you're already not a materialist. — khaled

however there are no apparent mental things — Kenosha Kid

You throw around ‘stuff’ pretty easily — Wayfarer

A further point is that the investigation of matter itself has yielded nothing like an indivisible particle — Wayfarer

The implication of the observer in the interpretation of physics is also by now a well-known aspect of modern science. — Wayfarer

Both minds and brains are things — khaled

You seem to be putting a lot of baggage on the word stuff that I didn't put there — khaled

The point about physicalism or materialism, is the claim that the only real existents are material existents - those entities knowable to the physical sciences, either actually or potentially. Everything else is purported to be able to be reduced to physical things and physical laws. — Wayfarer

Neither can be doubted.
And mind is not res cogitans,but is also physical and extended. — Mystic

Physicalism can’t really be ‘nuanced’. If it’s ‘nuanced’ then it’s no longer physicalism. — Wayfarer

There are many criticisms of physicalism, including the argument from the hard problem of consciousness, the nomological argument, the argument from reason, and so on. — Wayfarer

Nope. The mind is definitely not a thing. — Wayfarer

I can't think of anything they can't both say using their respective definitions. — khaled

I'm inclined to some combination of transcendental and epistemic idealism. — Wayfarer

The mind is definitely not a thing. — Wayfarer

A materialist would not say that humans have any mental things attached if "mental thing" is to mean some other different kind of substance from physical thing. If it means a particular pattern of physical thing then maybe. — khaled

A materialist would not say that humans have any mental things attached — khaled

if "mental thing" is to mean some other different kind of substance from physical thing. — khaled

If it means a particular pattern of physical thing then maybe. — khaled

You can still talk of minds and mental things like images, thoughts, feelings, but these arise from states of complex systems. — Kenosha Kid

For an idealist there is two different kinds of things, "mental stuff" and "physical stuff" — khaled

What’s something a materialist cannot say about the world that requires they be an idealist. Or vice versa — khaled

They ARE states of complex systems. — khaled

Point is that by the materialist definition you get everything an idealist would want. — khaled

A materialist cannot say about the world (with confidence) that consciousness can arise from non-conscious stuff. — RogueAI

They can assume and believe it's true, but there is (currently) no explanation for how that can happen — RogueAI

The materialist also cannot say (again, with confidence) that non-conscious stuff exists at all. There is no way to verify it. It's simply a belief. — RogueAI

Yes he can. Because consciousness to a materialist is a certain pattern of matter. You can easily tell when things follow said pattern. — khaled

You seem to already have in mind a particular effect called "consciousness" that we cannot detect that arises from matter. — khaled

That's not how a materialist would put it. To a materialist, again, consciousness is a pattern, not a seperate "secret sauce" added to things that have matter (usually). That's dualistic.

Consciousness is to a brain what a program is to a PC for a materialist. The program is not a seperate entity that acts on the PC, it's a specific configuration of the PC. — khaled