What is the difference between idealism and materialism?



I understand what materialism is, but idealism - not so much. I know however they are opposing views, and would like to know what are the differences.

Analogies would be greatly appreciated.

Bar Akiva

Posted 2018-02-11T13:19:45.390

Reputation: 151

This is the question of what is fundamental. For materialism, the basic entities of reality are material and the mental is not fundamental. For idealism the converse is true. – Quentin Ruyant – 2018-02-11T14:18:22.017

"I know however they are opposing views" - to be more precise, realism would be the opposite of idealism. – Yechiam Weiss – 2018-02-11T15:36:54.070

@QuentinRuyant I still don't understand. Care to elaborate? Do you have an example? – Bar Akiva – 2018-02-11T18:31:33.977

@YechiamWeiss and how is realism different than idealism? – Bar Akiva – 2018-02-11T18:35:19.833

@BarAkiva idealism, by definition (do note that many philosophers use varying adjustments to definition), is the world view that there is no "real" world outside of me, and everything I sense in the world is projections of my mind (Berkeley being the most popular idealist). Realism is the world view that there is an objective real world outside of me, that exists without being dependent on me. Objectivism and subjectivism is commonly associated with these world views (realism being the objectivism and idealism being the subjectivism). – Yechiam Weiss – 2018-02-11T19:49:15.217

1@YechiamWeiss I don't think this is an accurate portrayal of Berkeley's view. First, Berkeley went to great lengths to argue that by whatever standard of reality you might have, his account delivers the result that there is a real world outside of you. Second, Berkeley denies that the real world is a 'projection' of your mind, in the way that hallucinations or dreams or imaginings might be projections. Rather, real objects depend for their existence on their being perceived, but dependence doesn't entail projection (whatever exactly that amounts to) – possibleWorld – 2018-02-11T20:40:52.343

@YechiamWeiss Additionally, it's not true that realism is the opposite of idealism. Idealists typically think that the objects of their theory really exist. It's just that the offer a different account than the non-idealist of what that existence amounts to. – possibleWorld – 2018-02-11T20:43:34.977

@possibleWorld "[Berkeley's immaterialism] theory denies the existence of material substance and instead contends that familiar objects like tables and chairs are only ideas in the minds of perceivers and, as a result, cannot exist without being perceived." from Wikipedia. But this isn't about Berkeley, as I said every philosopher takes" idealism" slightly different from the other. And sure, many idealists don't inherently contradict realism (German idealists would be prime example), but they often don't use the common terms either, but rather as I've said, change them. – Yechiam Weiss – 2018-02-11T21:04:20.017

@YechiamWeiss Fair enough, but if we take your definition at face value then it looks like Berkeley, the arch-idealist of the western tradition, isn't an idealist. That looks like a prima facie reason to think that your definition misses something important. – possibleWorld – 2018-02-11T22:37:52.360

@BarAkiva for a materialist, the fundamental constituents of reality are material and everything mental is made out of material constituents. For an idealist to the contrary, the fundamental constituents of reality are mental and everything material is "made out of" (or depends on) mental entities. For example a materialist could say that your thoughts just are a set of neural firing. An idealist could say that a tree just is a set of perceptions (that of people seeing the tree). – Quentin Ruyant – 2018-02-11T22:41:03.403

@possibleWorld why isn't he an idealist? By your definition of idealism? Again from Wikipedia: "Idealism is the group of metaphysical philosophies which assert that reality, or reality as humans can know it, is fundamentally mental, mentally constructed, or otherwise immaterial". "Subjective Idealism [Berkley's idealism] describes a relationship between experience and the world in which objects are no more than collections or "bundles" of sense data in the perceiver." – Yechiam Weiss – 2018-02-11T22:55:45.970

@YechiamWeiss This should probably go to chat, but two things. First, my point was just that according to your initial definition Berkeley is not an idealist, because he denies that "there is no "real" world outside of" us. Second, it's pretty contentious whether or not Berkeley thinks that ordinary objects are bundles of sense data. He denies that external objects are material, and he thinks that they depend upon minds for their existence, but that's quite different from saying that they're just bundles of sense data. – possibleWorld – 2018-02-11T23:20:27.163

These kinds of vague and broad questions are best addressed by first googling and reading Wikipedia. Once you orient yourself some more you can ask here about difficulties understanding it more specifically, and we can answer more effectively.

– Conifold – 2018-02-12T00:10:55.140

@BarAkiva Idealism takes many forms. You might like to read a recent article by David Chalmers (not sure where) which describes the various forms. Regrettably he does not know the most significant and popular form of it (since it is 'mysticism'. 'nondualism' or 'transcendental/absolute idealism') and does not describe it, but he does a good job on all the rest. – None – 2018-02-12T11:30:40.053

Comments are not for extended discussion; the conversation between PeterJ and Conifold has been moved to chat. If you want to discuss Nondualism (i.e. the Indian one), feel free to go to this chat.

– Philip Klöcking – 2018-02-26T14:50:45.540



It's hard to give a once-and-for-all answer to this question, because what exactly materialism and idealism amount to depends largely on the historical era you have in mind.

That said, here's one way to cash out these notions. Materialism is the view that material objects exist. Idealism is the view that every object either is, or depends for its existence upon, mental entities.

Note that, as stated, these aren't opposing views, for it could be that material objects are either identical to or depend upon mental entities for their existence. (Edit: upon reflection I decided to redact the bit about Berkeley.)

However, anti-materialism sits pretty naturally with idealism, because if you deny that material objects exist you'll need some account of what objects are, and it looks like idealism offers a neat answer to that.


Posted 2018-02-11T13:19:45.390

Reputation: 1 038

What if somebody believes mental entities (ideal objects) don't exist. I'm asking because your answer seems to imply ideal(ism) is primary. But what if materialism vs idealism is actually an opposition (two poles which cannot be conceived of separately) rather than two streams of thought? – ttnphns – 2018-02-12T10:43:48.913

@ttnphns Sure, that's one way of characterizing out the positions. Like I said, the views I characterized aren't definitive, but are just one way you might go. – possibleWorld – 2018-02-12T17:05:25.300

@ttnphns - I'd say you're on the right track. A third choice is implied. – None – 2018-02-22T11:44:30.590


I can offer only one angle on a many-sided question. I largely agree with the first answer. Then in my own terms :


This typically means that only ideas exist - ideas in the, or a, subject's mind. Hence Bishop Berkeley's claim that all that exist are minds or spirits and their ideas. Point to a so-called object in the external world, say a chair, and the answer from an idealist is likely to be that he chair is just a collection or complex of ideas : we say it is brown, but that means just that we have a perception of brown. We say that it is solid, but that only means that we will experience the idea - a feeling - of resistance if we touch it.

Berkeley needs careful handling. On his account ideas cannot be the effects produced in us by objects in the external world. Then how do they originate ? Among the minds or spirits is God. God produces in us all our ideas. What's more, God controls all minds or spirits simultaneously and creates the aggregates of ideas that we call chairs, the sun, and other constants and continuants in what we (or 'the vulgar') take to be the external world. Some ideas exhibit a regularity in our experience which causes us to regard them as Laws of Nature.

Though the term 'idealism' does not derive from Berkeley - Leibniz had already used it and Berkeley doesn't use it so far as I know - Berkeley's use of ideas as fundamental (along with the minds that have them) suggests the origin of the term in the notion of ideas. Idealism is idea-ism and only 'idealism' for ease of language.


Various possibilities here but most, or quite, likely the view that all that exist are physical things. Everything that exists is purely physical and can be described in physical terms where the physical is whatever occupies a space/ time region.

This is an extreme form of materialism. Materialism can also refer to the view that them material has primacy, that it is fundamental and everything else dependent on or derivative from it. (Thanks to ttphns for reminding me of the distinction.)

This gives the broad contrast and I hope it helps.

Geoffrey Thomas

Posted 2018-02-11T13:19:45.390

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I wouldn't generally equate phenomena with ideas (although it is ok in some specific traditions of thought). – ttnphns – 2018-02-12T10:49:10.677

Materialism does not necessarily claim "everything is physical". It states material things are primary reality what exists, ideas - if there are - are secondary. – ttnphns – 2018-02-12T10:53:21.133

I didn't say 'necessarily' : I qualified my definition with 'most, or quite, likely' the view that all that exist are physical things. And there are forms of materialism that do hold precisely this. – Geoffrey Thomas – 2018-02-12T11:45:43.040

Left to myself I would not use the term, 'materialism', which is redolent of 19th-century philosophical controversies. I used the term only because the questioner had done so. – Geoffrey Thomas – 2018-02-12T11:51:37.803

@ttnphns. You are perfectly right; I should have alerted the questioner to distinctions within materialism. I have now done so - with acknowledgement. Thank you. Please excuse my earlier abruptness. – Geoffrey Thomas – 2018-02-12T11:59:52.737

@@ttnphns. I have removed the reference to phenomenalism, which I don't need and only confuses things. Thanks again. GT – Geoffrey Thomas – 2018-02-12T14:53:48.560

Out of curiosity, which term would you advise using in the 21st C in lieu of 19th C materialism? – Mozibur Ullah – 2018-02-13T02:46:42.213

@Mozibur Ullah. Hello again. The standard term nowadays in philosophy is (unexcitingly) 'physicalism'. I should have preferred this term, first, precisely because it is now the standard term in this area and, secondly, because 'materialism' is associated with classical physics & its rigid distinction between matter and energy and other pre-relativistic and pre-quantum ideas. I don't doubt that many people use the term 'matter' without attachment to these associations; and for everyday purposes this is harmless enough. – Geoffrey Thomas – 2018-02-13T09:11:58.313

@GeoffreyThomas - Agree about the old-fashioned nature of the term 'Materialism. I would say that the term 'Idealism' is also old-fashioned. If everything is an idea then there must be an ideator, in which case idealism is false. We have to get past these nonreductive ideas. – None – 2018-02-21T11:26:28.350

@PeterJ. I agree. Left to myself I wouldn't use the term 'idealism'. I was limited by the question. Even historically I find the term, like most labels, pretty useless. What do Berkeley, Kant and Hegel have in common by virtue of which they are all 'idealists' ? – Geoffrey Thomas – 2018-02-21T14:21:12.117


I would like to add another aspect of the contrast between materialism and idealism. This addition is not entirely different from what previous answers have laid out but attempts to emphasize a different perspective perhaps.

Materialism claims that the material world is real and ideas reflect the material conditions that humans find themselves in. In particular, ideas are not freely floating in the aether but necessarily reflect the material reality of the world in one way or the other, either directly or indirectly. In other words, ideas are generalizations and/or approximations that we make to organize the understanding of the material conditions in which we find ourselves. Idealism is in direct contention with materialism most prominently on this last point. Idealism views ideals as primary and the material world as either just an instantiation of a complex set of ideas or as an approximation of the ideal world, e.g. the geometric objects in the real world were seen as an approximation to the ideal objects in the Platonic world.

Oftentimes, much of the content of the analysis done in either materialism or idealism can survive in idealism or materialism respectively. One just needs to turn it on its head as Marx famously said when he gave the materialistic version of Hegel's idealist dialectic analysis.

Dvij D.C.

Posted 2018-02-11T13:19:45.390

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