Mod+ Idealism [Resources]



Like other resources threads, idea here is mostly to provide material for people wishing to investigate the topic.

Some commentary/debate is useful but please, if such discussion seems to be getting long [over 3-5 posts] create a separate thread and link to continue.


Three Dialogues Between Hylas and Philonous in Opposition to Sceptics and Atheists.

The First Dialogue

Hyl. I frankly own, Philonous, that it is in vain to longer. Colours, sounds, tastes, in a word all those termed secondary qualities, have certainly no existence without the mind. But by this acknowledgment I must not be supposed to derogate, the reality of Matter, or external objects; seeing it is no more than several philosophers maintain, who nevertheless are the farthest imaginable from denying Matter. For the clearer understanding of this, you must know sensible qualities are by philosophers divided into Primary and Secondary. The former are Extension, Figure, Solidity, Gravity, Motion, and Rest; and these they hold exist really in bodies. The latter are those above enumerated; or, briefly, all sensible qualities beside the Primary; which they assert are only so many sensations or ideas existing nowhere but in the mind. But all this, I doubt not, you are apprised of. For my part, I have been a long time sensible there was such an opinion current among philosophers, but was never thoroughly convinced of its truth until now.

Phil. You are still then of opinion that extension and figures are inherent in external unthinking substances?

Hyl. I am.

Phil. But what if the same arguments which are brought against Secondary Qualities will hold good against these also?

Phil. You are still then of opinion that extension and figures are inherent in external unthinking substances?

I am.

But what if the same arguments which are brought against Secondary Qualities will hold good against these also?

Hyl. Why then I shall be obliged to think, they too exist only in the mind.
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Gene Callahan offers some short posts critiquing a refutation of Berkeley's Idealism:

The Worst Argument in the World Is Stove's Own

"The view that objectivity signifies independence of experience because the notion (which it implies) of a world of existence outside experience is self-contradictory. If what is real is what is objective, what is objective must stand for something other than merely what is not subjective -- that which is untouched by consciousness, that from which experience has been withdrawn. For, in the first place, what is objective must, it would appear, be an object, and an object is always an object of consciousness. And secondly, a reality distinguished merely as what is interfered with by experience, must be unknowable and therefor a contradiction. Objectivity, then, if it is to be a characteristic of reality, must imply, and not deny, experience."
-- Michael Oakeshott, Experience and Its Modes, p. 59

Whether you buy the above or not, it is clearly not the very bad argument Stove sticks in the mouth of idealists.
How did Stove get Berkeley wrong?

Let us explore a little further how David Stove got Berkeley so wrong. As you may recall, he summarized one of Berkeley's arguments for idealism as follows:

"You cannot have trees-without-the-mind in mind, without having them in mind. Therefore, you cannot have trees-without-the-mind in mind."

But Stove had to add a step to Berkeley's argument to make it stupid: "without having them in mind." The actual argument is that you cannot have trees-without-the-mind in mind, period. What Berkeley is noting in the passage Stove cites is that when you attempt to have trees-without-the-mind in mind, you fail. And that failure is inevitable. "Trees-without-the-mind" is a mere abstraction, and to mistake mere abstractions for things that can actually exist is what Whitehead called "the fallacy of misplaced concreteness."


Listened to this last night, though I stopped right when he got to the reasons for believing in God as that isn't an interest of mine.

The part I listened to seemed like a good introduction.

Keith Ward on Idealism

What idealists maintain is that the ultimate nature of reality itself is mind-like, and that human and other finite minds are the best clues we have to what objective reality is like. The cosmos is not a mindless, unconscious, valueless, purposeless, yet somehow strangely intelligible, mechanism. Such a view is the result of extrapolating a machine-model, very useful in many scientific contexts, to provide the most comprehensive and adequate picture of the real cosmos.

Idealists propose that the human mind provides a better model from which to extrapolate to the cosmos as a whole. That is not because the cosmos looks like a very large human person or because there is some large person hovering just beyond the cosmos. It is because human minds play a creative and constructive role in producing the phenomenal world. They seem to point to a level of reality that is not merely phenomenal or an appearance to consciousness. Human minds generate an idea of reality as mind-like in a way that far transcends human mentality, yet that does include something like consciousness, value, and purpose as essential parts of its nature. (More Than Matter, p. 58)
I enjoyed the video about the dialogue between Hylas and Philonous (written by Berkeley). I think it's pretty much in line with Bernardo's thinking. One pundit I listened to on BBC radio's In Our Time programme expressed the view that Berkeley was actually still a kind of dualist, insofar as he claimed a distinction between mind and the contents of mind. But thinking about it, the "contents of mind" comprise what mind does. If mind didn't do anything--if it were devoid of thoughts--then what would it be? Nothing.

Mind is thoughts. It's semantics to have separate words for mind and the contents of mind. All that exists is thought process, which we tend to think of as occurring inside something, to which we apply the word "mind". The entire universe is thought process, but because of the restricted viewpoint from which we perceive it, it's hard to escape dualistic language; in fact, quite possibly dualistic language is a consequence of the way we perceive, which gives the irresistible impression that there is mind and that which is outside mind.

As much as anything, I think that may be because we seem to have what we call a (local) mind, and know there are things we don't know. If we did in fact know everything, then maybe we wouldn't perceive any kind of differentiation: everything would be unified thought process. So maybe dualism is a consequence of such ignorance we have on account of our restricted view of all that is. Maybe it is our ignorance that creates the impression of separation between mind and matter: it could actually be more of a distinction between what we know (and think of as being here in mind) and what we don't know (and think of as being there, e.g. matter).

Perhaps being alive and incarnate--being a "whirpool"--is an adventure in experiencing coming-to-know, which is a possibility barred to universal consciousness, because it knows everything that is to be known. After a while, that may become boring.


There’s no leaving the bubble of consciousness: Herbert Müller’s 0-D epistemology

By viewing certain structures as derived from, or referring to, a mind-independent reality (MIR), traditional metaphysics/ontology has painted itself into a corner. Because it assumes that our knowledge of the world is an internal (perceptual and/or conceptual) image or representation of an external world, it has to ask whether (or to what extent) this image or representation is accurate. But this question it cannot answer. We cannot compare the inner image with the outside world. All there is for us is our knowledge and our experience. George Berkeley expressed this in the clearest fashion when he said that we can only compare ideas with ideas. As was stressed by the German psychiatrist and philosopher Karl Jaspers (1947), the mind — consciousness, experience, awareness — is encompassing.

The question as to how something in the outside world (e.g., physical or electro-chemical processes in a brain, conceived as part of the outside world) can give rise to subjective experience, is therefore ill-conceived. It rests on the mistaken premise that mind and body are ontically separated, and that this separation has somehow to be overcome.


Physicist Richard Conn Henry Nature Essay on Idealism:

The Mental Universe

"The mental Universe The only reality is mind and observations, but observations are not of things. To see the Universe as it really is, we must abandon our tendency to conceptualize observations as things."


Crossover from Information & Reality thread about simulations in global-esque consciousness:


(Guy is a physicist who helped start the Digital Universe Foundation)
(See also this post by Jim Smith on the concept of a simulation running in the mind of God.)



On why Idealism is superior to Physicalism and Micropsychism -> (Discussion thread here.)

The Idealist Symbolism of the Christmas Archetype

The key point, however, is that cultures across time, geographies and languages have expressed this primordial notion that God imagines the world into existence, and then enters Its own imagination. Isn't this a fair way to also describe what happened when the Christ was born? Symbolically speaking, wasn't the Christian God also entering His own Creation in the form of Jesus, the man? The human mind, in its trans-intellectual and trans-linguistic depths, has always known something about this; somethingmore true than mere allegory, which it has expressed in profoundly symbolic, mythical forms.
The elevator pitch of a world in consciousness



(Discussion thread here.)

Peeking Behind the Icons

After you put on your helmet, you find yourself on a sandy beach with nine other players dressed not in the ugly high-tech bodysuits you saw just a moment ago, but in flattering bathing suits. You’re surrounded by palms trees and blue skies, with light puffy clouds. You hear the soft screeching of gulls, and the gentle pounding of surf. You see an off-white volleyball lying before you on the sand, and a volleyball net already set up...

Then you serve and the fun begins. You and the others are soon completely absorbed as you dig, set, feint, and spike with abandon. This goes on for a few wonderful minutes.

Then, suddenly, you are plagued with philosophical worries about the game you’re now playing. Between points, and in lulls in the action, question after question comes to mind. The first is this:

Are we all seeing and playing with the same volleyball?

The Interface Theory of Perception

A goal of perception is to estimate true properties of the world. A goal of categorization is to classify its structure. Aeons of evolution have shaped our senses to this end. These three assumptions motivate much work on human perception. I here argue, on evolutionary grounds, that all three are false. Instead, our perceptions constitute a species-specific user interface that guides behavior in a niche. Just as the icons of a PC’s interface hide the complexity of the computer, so our perceptions usefully hide the complexity of the world, and guide adaptive behavior. This interface theory of perception offers a framework, motivated by evolution, to guide research in object categorization. This framework informs a new class of evolutionary games, called interface games, in which pithy perceptions often drive true perceptions to extinction
Consciousness and The Interface Theory of Perception, Donald Hoffman

(Note criticism here, no idea if Hoffman knows about the claims made against him here. The paper below, Objects of Consciousness, does give more detail w.r.t the math.)

Despite substantial efforts by many researchers, we still have no scientific theory of how brain activity can create, or be, conscious experience. This is troubling, since we have a large body of correlations between brain activity and consciousness, correlations normally assumed to entail that brain activity creates conscious experience. Here I explore a solution to the mind-body problem that starts with the converse assumption: these correlations arise because consciousness creates brain activity, and indeed creates all objects and properties of the physical world. To this end, I develop two theses. The interface theory of perception states that perceptual experiences do not match or approximate properties of the objective world, but instead provide a simplified, species-specific, user interface to that world. Conscious realism states that the objective world consists of conscious agents and their experiences; these can be mathematically modeled and empirically explored in the normal scientific manner.

In support of the interface theory of perception, I present Monte Carlo simulations of evolutionary games in which perceptual strategies that see the truth compete with perceptual strategies that do not see the truth but are instead tuned to fitness. The result is that natural selection drives true perceptions to swift extinction. Our perceptions have evolved to guide adaptive behaviors, not to report the truth.

In support of conscious realism, I present a dynamical theory of consciousness in which the observer and the observed have precisely the same mathematical structure, i.e., in which there is a mathematically precise nondualism. I then derive the quantum wave function of the free particle from the asymptotic behavior of the conscious dynamics. This is a step toward solving the mind-body problem from the assumption that consciousness, not physics, is fundamental.

Conscious Realism

The theories so far proposed by scientists are, at best, hints about where to look for a genuine scientific theory. None of them remotely approaches the minimal explanatory power, quantitative precision, and novel predictive capacity expected from a genuine scientific theory. We would expect, for instance, that such a theory could explain, in principle, the difference in experience between, e.g., the smell of a rose and the taste of garlic. How, precisely, is the smell of a rose generated by a 40 Hz oscillation, a reentrant thalamocortical circuit, information integration, a global-workspace entry, the quantum state of microtubules, or the collapse of evolving templates ? What precise changes in these would transform experience from the smell of a rose to the taste of garlic ? What quantitative principles account for such transformations ? We are not asking about advanced features of consciousness, such as self-consciousness, that are perhaps available to few species. We are asking about an elementary feature available, presumably, to a rat. But no current theory has tools to answer these questions and none gives guidance to build such tools. None begins to dispel the mystery of conscious experience. As Pinker (1997, p. 564) points out, “. . . how a red-sensitive neuron gives rise to the subjective feel of redness is not a whit less mysterious than how the whole brain gives rise to the entire stream of consciousness.”

In short, the scientific study of consciousness is in the embarrassing position of having no scientific theory of consciousness. This remarkable situation provokes several responses...
Objects of Consciousness

t Current models of visual perception typically assume that human vision estimates true properties of physical objects, properties that exist even if unperceived. However, recent studies of perceptual evolution, using evolutionary games and genetic algorithms, reveal that natural selection often drives true perceptions to extinction when they compete with perceptions tuned to fitness rather than truth: Perception guides adaptive behavior; it does not estimate a preexisting physical truth. Moreover, shifting from evolutionary biology to quantum physics, there is reason to disbelieve in preexisting physical truths: Certain interpretations of quantum theory deny that dynamical properties of physical objects have definite values when unobserved. In some of these interpretations the observer is fundamental, and wave functions are compendia of subjective probabilities, not preexisting elements of physical reality. These two considerations, from evolutionary biology and quantum physics, suggest that current models of object perception require fundamental reformulation. Here we begin such a reformulation, starting with a formal model of consciousness that we call a “conscious agent.” We develop the dynamics of interacting conscious agents, and study how the perception of objects and space-time can emerge from such dynamics. We show that one particular object, the quantum free particle, has a wave function that is identical in form to the harmonic functions that characterize the asymptotic dynamics of conscious agents; particles are vibrations not of strings but of interacting conscious agents. This allows us to reinterpret physical properties such as position, momentum, and energy as properties of interacting conscious agents, rather than as preexisting physical truths. We sketch how this approach might extend to the perception of relativistic quantum objects, and to classical objects of macroscopic scale.


Physicist Richard Conn Henry Nature Essay on Idealism:

The Mental Universe

"The mental Universe The only reality is mind and observations, but observations are not of things. To see the Universe as it really is, we must abandon our tendency to conceptualize observations as things."
Some back & forth between Richard Coon Henry & critics


Some other stuff by him:

A Clearer Light

Quantum physics gets spooky(link is external)

Review of "The God Theory" by Bernard Haish(link is external)

Review of "Quantum Enigma" by Bruce Rosenblum and Fred Kuttner


Paul Marshall: Transforming the World Into Experience: An Idealist Experiment

Abstract: Idealism tackles the mind–body problem by giving precedence to mind and relegating matter to a dependent status. Contrary to popular opinion, idealism need not deny the existence of matter nor dispute the realist contention that objects exist independently of perceptual experience. However, idealism requires that matter and external objects are experiential or mind-dependent in a fundamental way.

I develop a form of idealism that affirms the existence of an external world, but makes it experiential. The characteristics of the external experience are taken to be akin to those of perceptual experience, but attention is given to some likely differences. An attempt to accommodate modern physics in the experiential account yields an idealism with panpsychic features.


Physics May Stonewall, But Reality Doesn't

Deepak Chopra, Menas Kafatos, Bernardo Kastrup

While the physicalists stonewall, and gather popular opinion on their side, a growing cadre of physicists, including Nobel laureates like Brian Josephson and neuroscientist Sir John Eccles, grappled with the profound issue of mind and matter without prejudice. It may be true that neither the “mind first” camp nor the “matter first” camp have grasped what reality is actually trying to tell us. Instead of saying that molecules somehow learned to think, which is the basic claim physicalists make in order to explain the mind—a claim with zero basis in fact—it may be that matter exists because mind exists. By the same token, the “mind first” camp, which explains physical objects by saying that they are created by the mind—a position with surprisingly strong evidence behind it—it may be necessary to redefine the mind so that creation can simultaneously be conscious and physical.
Making a Choice: Is the Universe Mental or Physical?

Deepak Chopra, MD, Menas Kafatos, PhD, Bernardo Kastrup, PhD, Rudolph E. Tanzi, PhD

The possibility of a mental universe has a strong lineage going in the quantum era, but present-day physicalists (physicists who accept the physical nature of reality as a given) feel free to dismiss or ignore figures as towering as Max Planck, Werner Heisenberg, and John von Neumann. We discussed them in our last posting. Physicalism holds sway with the vast majority of cosmologists, and yet Andre Linde of Stanford University made some important points in an article on the most current theories of the inflationary universe: “…carefully avoiding the concept of consciousness in quantum cosmology” may artificially narrow one’s outlook.” (Link:

As a result, Linde points out, a number of physicists have replaced “observer” with “participant” when describing how humans interact with the universe. Others use the phrase “self-observing universe.” It’s startling when an important authority on the inflationary cosmos opens the door for human participation as a key element. Linde asks the same question posed by many quantum pioneers a century ago: “Is it really possible to fully understand what the universe is without first understanding what life is?”

Linde stops at the threshold of entering the mental universe, merely pointing out that the assumptions of materialism are questionable when reality is examined at deep levels. Every theorist has a right to be as cautious as he wants. But the fact is that quantum pioneers arrived at those deep levels of reality long ago, while scientists using the very same modern physics ignore them as if physicalism will triumph in the end. Given enough subatomic particles, advanced mathematics, a zillion other possible universes to toss into the equation, and an ever more sophisticated version of cosmic inflation, all the answers will pop up—so the standard thinking goes.
Why do the keep polarising things... is it this 'or' that? It's both... it's one process leading to a result.

Still confusing observer and observed, measurement with observer, objective with subjective... Etc etc.... you can see they are all talking about a subset of the same stuff from different perspectives... inflexible and rigid perspectives.
"Still confusing " information at a source with mutual information


Charles Sanders Peirce

Peirce developed an architectonic theory of cosmos, mind, and signs, explaining the commonality of physical, psychical, and semiotic phenomena. He believed that theories, generals, and paradigms shape the future and give rise to reactions to themselves. His was a unified theory of all that gives cosmic significance to human behavior (Sherrif 1994, pp. 18-19).

Because of our interest in theory, I decided to begin with Peirce’s discussion of how we come to form theories that explain the constitution of things. This will eventually take us to Peirce’s cosmology and a remarkably cogent bottom-up view of the emergence and development of the universe, a view which has at its center the belief that mind constitutes the very fabric of the real. Although this metaphysical view provides a solid platform for a solution to the mind-body problem, for Peirce that question is secondary to the core concept that the world is in its very essence meaningful, a profusion of signs that constitutes and makes intelligible every existing thing (CP 4.55).

This paper is necessarily limited in scope. It cannot adequately deal with all the questions that naturally arise concerning the relationship between Peirce’s ideas and our search for a theory of rogue phenomena and survival. It is meant, rather, to provide enough information about his overall vision to usefully formulate such questions.

A preliminary note: You will find this paper liberally stocked with direct quotations from Peirce. This may well not be considered good academic form, but I do it for two reasons. One is that Peirce’s works are not all that well known yet and probably not sitting on the shelves of the majority of people who will read this paper for ready reference. The second, and most important in my mind, is to give the reader a feeling of the style and way of thinking of this remarkable mind. I cannot think of a better way to get a sense of the man than through his own words.


Idealism: Past, Present, and Future

Idealism has ancient roots in both Western and Eastern philosophy. In Eastern philosophy, Idealist themes can be found in the Indian philosophies of the Vedanta and Yogacara Buddhism. Vedanta is the more ancient of these: it conceives of the ultimate ground of reality or "Brahman" as pure "self-luminous" consciousness. Continuing Vedantic themes in a Buddhist setting, Yogacara Buddhism claims that only "pure mind" is ultimately real. In Eastern philosophy, however, Idealism often goes hand in hand with mystical acosmism, where the full reality of the empirical world is denied in contrast to the mystical state of pure, contentless consciousness reached in meditation. This happens paradigmatically in the non-dual Vedanta of the 8th century Indian philosopher Shankara.

For a more positive evaluation of the empirical world from an Idealist perspective we must turn to Idealism in the Western tradition. This is not to say, however, that Eastern Idealism has no value. Moreover, some Idealists of the Western tradition (Parmenides, Schelling, Bradley) have come awfully close to the mystical acosmism of their Eastern counterparts.

In Western philosophy the tradition of Idealism arguably started with the Presocratic philosophers Anaxagoras ("it is intelligence that arranges and causes all things") and Parmenides ("thinking and being are the same"). They passed the torch to Plato, who famously saw the empirical world as an image or expression of eternal Ideas. Plato in turn bequeathed the Idealist vision of the universe to Plotinus, who added to Platonism the Aristotelian conception of God as "thought thinking itself", thereby arriving at a picture of the universe as the "emanation" of the One's self-contemplation. In this way Plotinus effectively anticipated the Absolute Idealism of the post-Kantian German Idealists Schelling and Hegel.

But before the latter could arrive on the scene, modern philosophy first had to take the epistemological turn, notably through Descartes' focus on individual self-consciousness as the paradigm of certain knowledge. From Descartes onwards, Idealism took on a subjective flavor, centering on the epistemological argument that our knowledge of reality is confined to our own thoughts and perceptions (Berkeley, Kant).

The post-Kantian German Idealists, although starting from this epistemologically inspired Idealism, arguably returned to Idealism's more ontological beginnings in Greek philosophy, combining the Cartesian focus on the cogito as the paradigm of certain knowledge ("Absolute Knowledge") with the more Neoplatonist focus on "thought thinking itself" as the teleological origin of the empirical universe.

In the second half of the 19th century, the legacy of German Absolute Idealism was taken up and further developed by the British Idealists (Green, Bradley, McTaggart, Bosanquet, Collingwood, Whitehead e.a.) and the American Idealists, most notably Royce. On the European Continent the tradition of Idealism was continued by Husserl.These philosophers took Idealism into the 20th century, enriching it with themes from contemporary logic, mathematics, and natural science. In the beginning of the 20th century, however, British and American Idealism were all but effaced by the emergence of logical empiricism and analytic philosophy. The original proponents of the latter, notably Moore and Russell, asserted their own position through vigorous opposition to and ridicule of their Idealist predecessors, resulting in a distorted caricature of what Idealism really amounts to.

In present times, however, this caricature is in the process of being corrected, and Idealism is experiencing a revival owing to new developments in philosophy and science. Four must be singled out for special attention:

(1) The so-termed "hard problem of consciousness" and the influence of Russellian monism: Conscious states or "qualia" appear to be irreducible to physics and even to be the sole candidates for being the intrinsic entities on which physical structure rests, thereby suggesting a panpsychist ontology (e.g. Galen Strawson).

(2) The emergence of Normative Idealism in opposition to physicalistEliminativism: Philosophers like McDowell and Brandom have made a remarkable return to Kant and Hegel by pointing out that conceptuality and rationality in general are intrinsically normative, having to do with how people ought to think rather than with how they factually think. Thus, given the conceptually laden impact of empirical experience on thought, the empirical world must have a normative significance that cannot be accounted for in strictly naturalistic or scientistic terms. According to philosophers like McDowell and Brandom, the empirical world turns out to have a normative-conceptual structure that is best approached by returning to the Idealisms expounded by Kant and Hegel.

(3) The focus on "observer participancy" in contemporary physics: The role of conscious observation in quantum mechanics and the apparent fine-tuning of the universe for the evolution of intelligent life (i.e. the anthropic principle) have, together with the hard problem of consciousness, suggested to some physicists (e.g. Von Neumann, Wigner, Wheeler) that consciousness plays a more fundamental role in the universe than physical science has traditionally assumed. In this way physics could lead to a scientific reanimation of Idealism.

(4) The rediscovery of (Neo-)Platonic Idealism in relation to Leibniz's question: There is at present a remarkable revival of interesting in Leibniz's famous question, "Why is there something rather than nothing?". Various philosophers and physicists have rebegun to develop possible solutions to this most fundamental problem. In this context the ontological importance of (Neo-)Platonic Idealism has been rediscovered by philosphers like Leslie and Rescher. Agreeing with other philosophers, such as Nozick, that the ultimate cause or ground of existence must also be self-causing or self-grounding (in order to avoid a regress), Leslie and Rescher argue that the self-explaining principle underlying existence is best conceived in terms of value, analogous to Plato's and Plotinus' focus on the "Good beyond Being". Value, as Leslie and Rescher point out, explains existence, because it is good that there is existence, and at the same time value explains itself as well, because it is good that there is goodness. In this way the (Neo-)Platonic focus on the Good as the self-grounding of ground of existence has made a remarkable return in contemporary philosophy. What is lacking, however, in both Leslie and Rescher is a proper acknowledgement of the role played by absolute self-awareness in this ontological self-grounding. In this regard they lag behind Plotinus who not only conceived of the One as the "Good beyond Being" but also as absolute self-awareness, such that "its being is its act of looking at itself" as Plotinus writes. Since, as remarked, Plotinus in this regard anticipated the Absolute Idealism of Schelling and Hegel, the introduction of the latter into the current debate about Leibniz's question remains one of the desiderata of future research in Idealism.
As the above history of Idealism makes clear, albeit in a very truncated fashion, Idealism is by no means a single school or system of thought. Besides the dispute between Idealism and Materialism or Physicalism, there is also the internal dispute between rival schools of Idealism. Something of this disagreement already appeared above when it was said that "Idealism can be defined by acceptance of the premise that the universe is first and foremost a manifestation of mind or reason". The disjunction -- mind or reason -- signals a disagreement among Idealists concerning the nature of that ultimate ground underlying the empirical world. Is that ground a mind in a subjective sense, as in (self-)consciousness or selfhood? Or should we rather banish subjectivity from the Idealist explanation of the world, focusing rather on an impersonal and objective reason ("logos") as the ultimate ground or reality? Given this disjunction, Idealist philosophy forms a gradient spectrum between the extremes of subjectivism and objectivism. Roughly the following positions can be distinguished:

(1) Objective Idealism: Empirical reality is the manifestation of objective, non-personal and non-spatiotemporal ideal entities, such as Plato's Ideas, or mathematical structures as in Mathematical Platonism. The latter is currently advocated by physicists like Penrose and Tegmark. Normative Idealism (McDowell, Brandom), with its focus on the constitutive importance of publicly valid conceptual norms, also seems to be a species of Objective Idealism.

(2) Subjective Idealism: Empirical reality exists only for a conscious subject who constructs it on the basis of its experiences and a priori cognitive structures. We can know nothing about reality as it exists apart from the knowing subject. In its phenomenalist version, this position was advocated by Berkeley. In a more rationalist vein the position was advocated by Kant and Fichte.

(3) Absolute Idealism: There is nothing apart from the absolute Self or Spirit that unfolds itself in the empirical world. In a sense Absolute Idealism combines Objective and Subjective Idealism in that it conceives of the ultimate ground of reality as an ideal Self or Spirit whose self-realization involves the Ideas highlighted in Platonism. This position has been famously advocated by Schelling and Hegel, though in important ways they were already anticipated by Plotinus and later Neoplatonists (e.g. Proclus, Eriugena).

(4) Panpsychist Idealism: This is the view that consciousness, mind or soul is a universal feature of all things. It doesn't necessarily say that all physical objects are manifestations of mind but it does say that all physical objects have mind or at least an aspect of mentality. Panpsychism may go hand in hand with metaphysical pluralism, stating that the universe is a collection of countless many minds. Famous Panpsychists are Thales, Spinoza, Leibniz, James, and most recently Galen Strawson. Panpsychism is in itself a very diverse doctrine, and its relation to the other forms of Idealism has up till now not been properly dealt with. This is one of the desiderata of future research.