The problem of universals

Have realist and idealist philosophies now converged?

Copyright 2016 Graham Berrisford. One of about 300 papers at Last updated 13/01/2019 12:57


This paper is a supplement to The philosophy of system theory, addressing “the problem of universals

A universal is a property, quality, characteristic, attribute or type such as “tall”, “yellow”, “circular” or “dangerous”.

We describe particular situations, entities and events by attributing universals to them.

Sometimes, we attach a measure or degree to the property, like 2 metres tall, or very dangerous.


The basis of verbal description


<create and use>              <typify>

Describers   <observe and envisage >  Particulars


The problem of universals is the question of whether universal properties exist - or what it means to “exist”.

Traditionally, “realist” and “idealist” philosophers disagree on whether universals exist independently of thought and speech (and records of those).

Philosophers, mathematicians and scientists have debated this for millennia, at least since Plato and Aristotle.


This paper concludes that to a psycho-biologist, the problem of universals is something of a fake problem.

Or at least, the distinction between realist and idealist philosophical positions is a false distinction.

Over centuries, idealism and idealism have evolved into a confusingly diverse and overlapping mess of different positions.

And today, what this paper calls Scientific Idealism and Scientific Realism are much the same.


Description and reality. 2

Universals and particulars. 3

Philosophical positions and answers. 3

Realism: a property exists independently of any mind or description. 3

Nominalism: a property exists only when a thing has that property. 4

Idealism: a property is constructed in the mind, so exists only in descriptions of things  5

Truth.. 7

Conclusions, remarks and FAQs. 8

Footnotes: Challenges to Scientific Idealism... 12


Description and reality

Philosophers have long debated the nature of description and reality.

“The distinction has a curious status in contemporary philosophy.

It is agreed the distinction is of fundamental importance.

Yet there is no standard account of how it should be drawn.


How to phrase the questions we want answers to?

Do realities have descriptions, which describers discover?

Or do describers create descriptions to help them deal with realities?

Which comes first: descriptive types or realities?


Philosophers don’t necessarily put questions that way.

So they may not agree with the table below, which is merely a device to get you thinking.


Descriptive types exist first

before realities exemplify them

Realities exist first

before descriptive types are applied to them


Realities have descriptions

Platonic Realism

Things exemplify eternal types

Aristotlean Realism

Types don’t exist outside of things


Describers create descriptions

Metaphysical Idealism (e.g. Berkeley)

Mentality is the foundation of reality.

Things exist only when observed.

Epistemological Idealism (e.g. Kant)

Types are the products of minds.


“There are many philosophical positions regarding universals.

Taking "beauty" as example, three positions are:

·         Platonic realism: beauty is a property that exists in an ideal form independently of any mind or description.

·         Aristotelian realism: beauty is a property that exists only when beautiful things exist.

·         Idealism: beauty is a property constructed in the mind, so exists only in descriptions of things.” Wikipedia, May 2017


What a philosopher believes, how they describe their beliefs, and how their descriptions interpreted are not always the same.

The terms realism and idealism are used in various ways by different philosophers.

Partly because the words reality, mind, existence and description mean different things to different people.


·         Do realities include the contents of minds - thoughts, speech and documentation of them?

·         Are minds limited to human brains? What about honey bee brains, or the biochemistry of sunflowers following the sun, or computer software?

·         Does existence imply a material or physical form, locatable in time and space? If not, what does it mean?

·         Are descriptive property types (variables such as beauty) universally defined and agreed?

Universals and particulars

Remember this table from our system theory papers?


Abstract system description

A set of roles and rules (the logic or laws actors follow)

Concrete system reality

Actors playing the roles and acting according to the rules


This table similarly contrasts universals and particulars.



General properties, qualities, characteristics, attributes, types or concepts used to describe particular things


Real-world things that may be described.


The table below pairs some examples of things with some types.

(Bear in mind the names of the things are placeholders for the concrete realities you must imagine.)


Some universal types








Some particular things


Rose bushes



Chocolate bars




The problem of universals is the question of whether property types exist - or what it means to “exist”.

Particular chocolate bars are describable, classifiable or typifiable as “tasty”.

You can readily remove a particular chocolate bar from the universe by eating it.

Can you also remove the general type called “tasty”? Or does it exist forever as an eternal universal?

Philosophical positions and answers

The debate here is not about whether reality exists independently of description (of course it does).

Or whether we can describe a given reality in one ideal or perfect way (of course we cannot).

The debate is only about whether some or all descriptive types exist as “universals.”

And whether a type exists in an eternal ethereal form, outside of space and time, independently of life, thought and record of it.


The Stanford encyclopedia entry presents the problem of universals thus:

“Since types are usually thought to be universals, the debate over whether they exist [independently of thought and life] is as longstanding as the debate over universals, and debaters fall into the same camps.

Realists say they do [universal exist independently of thought and life].

Nominalists who renounce universals and abstract objects, say they don't.

Conceptualists [Idealists] argued that there are no general things such as the species homo sapiens; there are only general ideas—that is, ideas that apply to more than one thing.”


Unfortunately, the encyclopedia entry swiftly dismisses conceptualism (aka idealism) and ignores it thereafter.

Yet idealism is not so much a philosophy as the stance taken by a psycho-biologist regarding semiotics and epistemology.

The idealist finds no use for a type (concept or quality) that is not symbolised somewhere in space and time.

And since the notion of a “Platonic ideal” is not needed, it can be cut out using Occam’s razor with no loss to science.

Realism: a property exists independently of any mind or description

“The realist school claims that universals are real—they exist and are distinct from the particulars that instantiate them.

Platonic realism is the view that universals are real entities and they exist independent of particulars.

Aristotelian realism is the view that universals are real entities, but their existence is dependent on the particulars that exemplify them.” Wikipedia, May 2017


The position here?

A property (say, “musicianship”) does exist independently of any particular individual describable as having the property.

If all musicians in the world died, then the concept of musicianship would still exist in thought, speech and documentation.

But the concept of musicianship did not exist before there was a mind to produce thought, speech or documentation of the concept.


Roger Penrose contends that the philosophy of mathematics can only be understood by taking the Platonic realist view.

That argument is addressed briefly in the conclusions below, and at greater length in another paper.


Having said that, a position known as Scientific Realism is currently favoured by many.

See for example: “Scientific Realism: How Science Tracks Truth” Psillos S. London: Routledge, 1999.

Another source defines Scientific Realism as below.


Scientific Realism

The world has a definite and mind-independent structure.

Scientific theories are true or not because of the way the world is

Our best scientific theories are approximately true of the world.


Nominalism: a property exists only when a thing has that property

Nominalists assert that only individuals or particulars exist and deny that universals are real (exist as entities or beings).

The nominalist philosopher agrees that we predicate the same property of multiple entities but argues that the entities only share a name, not a real quality, in common.” Wikipedia, May 2017


The position here?

You would be foolish to act as though standing on a railway track shares only a name with other “dangerous” situations.

What matters is that it really does have a describable quality, which happens to be represented or encoded as “dangerous” in the English language.

We must translate mental models into a shared language to discuss them, but the concept of danger is not inherently linguistic.

Rather, the names we give to properties are merely labels we use to share information, share our perceptions of reality.


As children we are nominalists to a degree.

My son learns type names by pointing to a thing and asking: What’s that thing?

I tell him that thing is a “rose bush”, and so shares my type name with him.

That doesn’t mean he understand the general type, or shares it with me.

It is only through repeated interactions that people in a social network learn to align the type definitions they associate with everyday words.


Later, my son may learn a type elaboration that defines the type named “rose bush”

E.g. the elaboration associates the concept called “rose bush” with concepts called “flowering”, “thorny” and “bushy”.

Thus, his mental models embed one concept in a network of inter-related concepts - much as in a dictionary.

Idealism: a property is constructed in the mind, so exists only in descriptions of things

“Idealists, such as Kant and Hegel, posit that universals are not real, but are ideas in the mind of rational beings.

Idealists do not reject universals as arbitrary names; rather, they treat universals as fundamental categories of pure reason (or as secondary concepts derived from those fundamental categories).

Universals, in idealism, are intrinsically tied to the rationality of the subject making the judgment.”


“For instance, when someone judges that two cup holders are both circular they are not noticing a mind-independent thing ("circularity") that is in both objects.

Nor are they simply applying a name ("circular") to both.

Rather, they partially constitute the very concept of cup holder by supplying it with the concept of circularity, which already exists as an idea in their rational mind.”

Thus, for idealists, the problem of universals is only tangentially a metaphysical problem; it is more of a problem of psychology and epistemology.” Wikipedia, May 2017


To an idealist, universals are types; particulars are things that instantiate types.

And the graphic below represents Kant’s epistemological idealism.


Epistemological idealism


<create and use>               <idealise>

Rational actors  <observe and envisage>  Particulars


E.g. “Planet” is a type; particular cosmic bodies are things that instantiate that type.

An idealist view of the solar system can be represented in a triangle.


The “Planet” type

<create and use>               <idealises>

Astronomers <observe and envisage> Particular cosmic bodies


To an idealist, cosmic bodies existed before the type “planet” was name and described.

Other types (like “spherical”, “solid”, gas giant”, “earth-like”) might be abstracted from observation of the same cosmic bodies.

Other types (like “cuboid planet”) may be proposed that are fanciful – never to be realised in a particular thing.


More generally, things cannot be described as instantiating a type until that type is described.

Also, infinite types might be abstracted from things we observe or envisage.

And types (like “unicorn”) can be purely imaginary – never realised in a particular thing.


Kant's presumption that knowledge can only be gained through experience begs definitions of "knowledge" and "experience".

Evidently, we acquire:

·         knowledge of how sharp a knife through experience

·         knowledge of arithmetic and geography through communication during formal education

·         knowledge of how much fuel a rocket needs to reach the moon by the application of logic

·         the knowledge that jumping off a cliff is dangerous by inheritance.


However it is acquired, knowledge is empirically verifiable by testing of real world structures and behaviors (see the Truth section below).


The position here?

Reality is out there, but we cannot understand reality directly, exactly as it is.

We create and use concepts (like “circle”) as a means to understand and deal with particulars.

Also, to describe fantasies (like “unicorn”).


One type can be instantiated by zero, one or many things.

And conversely, one thing can instantiate zero, one or many types.


Things are not instances per se; they are only instances when associated with types.

A face is beautiful only in description of it; a wheel is a circle only in a description of it.

Descriptive types are called universals because they are so widely recognised and useful as models of reality.

But still, they are products of rational beings.


This position may be called Scientific Idealism, though it is close to Scientific Realism.


Scientific Idealism


<create and use>               <idealise>

Life forms       <observe and envisage>      Realities


Our position is that animals have evolved to remember and share descriptions of realities.

We create and use descriptions (mental, linguistic and other models) as a means to understand and deal with particular realities.

Our models need only be accurate enough to predict real world behaviour in a way that helps us.


Scientific Idealism

The structure of the world is composed of separable particulars/things.

Universals/types are constructs of the mind that rational actors use to classify and describe particulars/things.

Universals/types are tools for understanding and dealing with the particulars they describe.


A reader has written:

“If you are an Idealist, then there is no independent ‘state of affairs’ that makes your ideas or assertions ‘true’. So you must live in a post-truth world.”

This kind of thinking appears in the commonly-used phrase “perception is reality”.

Some socio-cultural thinkers appear to believe the post-modernist idea that all perceptions are equally valid.

Some deprecate trying to apply the scientific method in favour of the “dialectic”, as Marxists call it.


One oft-liked post on the internet says: “Your intentions don't matter. If people perceive you the wrong way; it doesn't matter what your intentions are.”

But in important ways, it certainly does matter what your intentions are!


Idealists don't deny the existence of a mind-independent reality.

The question is rather about how accurately descriptions convey the qualities of those realities.

We can determine their accuracy by testing our ideas and assertions in every possible way - empirically, logically and socially.


As related papers explain, knowledge is fuzzy, there are degrees of truth.

You can point to a particular thing and describe it as “circular”, but on close inspection, nothing is perfectly circular.

Your listener might decide it is circular enough for their purposes as a circus ring designer.

Or not circular enough for their purposes as a bicycle wheel designer.


A truth triangle

True-enough propositions

<create and use>       <describe and predict>

Rational actors    <observe and envisage>     Realities


Two descriptions may be incompatible, yet both true enough for particular purposes.

For example, scientists describe photons (and other elementary quantic entities) in terms of particles and/or waves.

Neither universal - "particle" or "wave" - can fully describe the behavior of light.

Waves and particles are both mental models that are useful (accurate enough) in different contexts.


Wave-particle duality

Wave and Particle Descriptions

<create and use>                  <idealise>

Scientists           <observe and envisage>               Light


In the world of quantum mechanics, even the values given to property types (such as “position” and “speed”) are seen as creations of observers.

“If you accept quantum physics at face value then at least one of two dearly held principles from the classical world must give.

One is realism, the idea that every object has properties that exist without you measuring them.

For most quantum physicists, it’s realism that has to give.” Anil Ananthaswamy “New Scientist” 13 December 2014


So, idealists don’t live in a post-truth world.

They live in a world where descriptions are true enough models of reality to be useful when reacting to and predicting realities.

And descriptions can be shared by animals that share the language used to form the descriptions.

Conclusions, remarks and FAQs

This paper concludes that to a psycho-biologist, the problem of universals is something of a fake problem.

Or at least, the distinction between realist and idealist philosophical positions is a false distinction.

Both the problem and the distinction are created by posing questionable questions and using questionable words.

Over centuries, idealism and idealism have evolved into a confusingly diverse and overlapping mess of different positions.

But today, what this paper calls Scientific Idealism and Scientific Realism are much the same.


For sure, some disagree on whether univerals exist in reality or merely in thought and speech (and records of those).

But to a psycho-biologist, this is a false dichotomy.

Because thought and speech (and records of those) are part of reality

They are products of biology that evolved to help animals survive by remembering and representing reality.


This table presents a simplistic history of thinking about things (particular realties) types (universal descriptions) and minds (intelligences).




Types exist eternally, before and after things that instantiate them.


Types exist only in things that instantiate them.


Things exist only when described/typified by a mind.


Things can exist before minds create types to describe them.

System designer

Types can be created in the mind before things exist to instantiate them.


Scientific Idealism combines the last two of these views.

It sees universals as types or descriptions that are conceived by rational actors.

Moreover, they exist in reality - in mental, documented and other kinds of model.


·         Do realities include the contents of minds? Yes

·         Are minds limited to human brains? No. Other animals are mindful.

·         Does existence imply a material or physical form, locatable in time and space? Surely yes, else it has no useful meaning.

·         Are descriptive property types (variables such as beauty) universally defined and agreed? No. They are products of biological evolution.


Some more philosophical questions

Scientific Idealist answers

Do realities exist that have never been described?

Yes. The existence of mind-independent things is not disputed (above the level of quantum mechanics).

Do descriptions exist that have never been realised?

Yes. We can envisage a “flying horse” though no things of that type exist in reality.

Do minds exist outside and independent of reality?

No. They are biological things; they are part and parcel of the real world.

Do minds exist without and independent of descriptions?

No. Mindfulness implies the ability to observe, envisage and describe realities.

Do descriptions exist that have never been conceived in a mind?

No. Descriptions exist in minds and the products of minds (see discussion below).


Q) How does this apply to system theory?

The Scientific Idealist view of systems can be represented in the same triangle as above.

Abstract system descriptions are types; concrete systems are things that instantiate system descriptions


Abstract system descriptions

<create and use>                  <idealise>

System describers   <observe and envisage>   Concrete systems


Note that a discrete real-world entity (e.g. a named business or machine) cannot rightly be called a system until that system is described.

Also, infinite systems might be abstracted from any business or machine we observe or envisage.

And envisaged business systems (“target systems”) can be purely imaginary – never realised in a particular business


The realities of interest are those which can be observed or envisaged and described.

The questions for us are not so much whether types and properties (dangerous, thorny, good, beautiful, circular, customer and address) exist.

The questions are rather these.


Q) Do universal types (e.g. “circle, “planet”or “customer”) exist without actors to create and use them? No

With no actors there is no abstraction and no mind-independent idea.

Has there ever been a perfect circle in the real world?

The things now called planets existed in the universe before life, but there was no concept of a planet.


Q) Is every type indisputably defined? No

There might no a universal agreement about exactly what a rose bush is.

The definition of the concept or type we label “rose bush” is a kind of jury decision.


Q) Is everything indisputably of a type or not? No

The conformance of any particular plant to the general rose bush type may be loose or fuzzy.


Q) What about numbers and the rest of maths?

Numbers and circles are rigorously defined using the rules of logic, with respect to axioms

These types now exist in countless mental and documented models.

The type definitions include operation types that can be performed on numbers and circles.

All over the world, people use these universal operations to perform calculations on particular numbers and circles

Which is to say, number and circle types are excellent tools for modelling reality.


Roger Penrose contends that the philosophy of mathematics can only be understood by taking the Platonic realist view.

"mathematical truth is absolute, external and eternal, and not based on man-made criteria ... mathematical objects have a timeless existence of their own..."

However, this contention depends how the term "existence" is interpreted.

A realist may say that mathematical objects exist eternally in an ethereal or logical sense.

To an idealist, the term “existence” implies instantiation in a material or physical sense.


For sure, mathematical types (e.g. number) and instances (e.g. 2) have long existed in minds and their products.

And humans rely on numbers to understand and predict realities.

Mathematical types are so widely shared, so successful, you might believe them to be mind-independent.

But Scientific Idealism takes the view that they are mind-dependent.

However many times the type called “circle” is conceived, it remains a product of intelligence.


It seems reasonable to call numbers and circles universals, because they are so widely shared and so successfully used.

But it also seems self-aggrandising to believe that our mental models are so important they exist outside of minds and the products of minds.

Surely, the concept of number or circle did not exist before life? And has there ever been a perfect circle?

An explanation of how numbers emerged through biological evolution is given in The philosophy of system theory.


Q) Does everything exist before it is described? No

Countless things existed nature before they were described.

But designed things (symphonies, chairs and software programs) only exist in the world after they have been described

They are the products of minds in which some kind of description was formed before the thing was made.


Q) Can we reason about concepts/properties/types using only their names? No

You cannot reason knowing only a type name (like number, circle, rose bush or planet).

You can only reason when you know the properties of that type – to be found in some kind of type elaboration.

Given a small and simple concept (like number or circle), you can readily hold it properties in mind and reason about it.

Given a large and complex concept (like a business system), it is so difficult to remember its properties and reason about it that a written description becomes essential.


Q) Do concepts in exist in a collective consciousness? No

One mathematician has written that: "Numbers do not have a tangible existence in the world [rather] they exist in our collective consciousness.”

Numbers do exist in perceptible forms, internally in mental images and externally in documents.

But since there is no “collective consciousness”, we each learn the concept of number though a mix of inherited mental ability and education.


Q) Are simple universal types differentiable from more complex parochial types? Yes

There seems to be a spectrum from the former to the latter.





Simple, logical types

Hard science

“Number” and “Circle”

appear widely understood and not open to interpretation or judgement.

Natural types

Everyday experience

“Beauty” and “Danger”

more open interpretation or judgement.

Complex, parochial types

Law and business

“Homicide” and “Bank account”

understood only in a “bounded context” or “domain of knowledge”.


Note however that one type of number is defined differently in the Java and C++ programming languages.

Footnotes: Challenges to Scientific Idealism

You might argue Scientific Idealism would be better labelled Scientific Realism.

What follows is a response to that argument.


Are universals mind-independent to the extent that they exist eternally?

If realism means proposing that a universal quality or concept is eternal, that is to postulate something outside of time and space.

There is no fossil, geological or cosmological evidence of concepts before life.

The existence of a concept before cannot be proved or falsified.

It seems a pointless proposition, a fancy, a useless idea, and Occam’s razor can be used to remove it.


It is more pragmatic to propose every universal concept has a life history.

To begin with there was no thinker and no thought; no conceiver and no concept.

Then thinkers evolved.

A concept is born whenever a thinker conceives a concept (be it “circle” or “flying unicorn”)

A concept is encoded in at least one mental, documented or other kind of model.

A concept may be shared and copied any number of times.

If and when all copies are destroyed, then the concept disappears from the current state of the universe.


If it were possible to live in a world without types, we could still name individual things, situations, entities and events.

But we could not describe things as instances of types.

Because a thing cannot be called an instance until there is a type to which it conforms


It seems egoistic or anthropocentric to believe that human knowledge is so fundamental to the world it must have existed before human life.

Scientific Idealists posit knowledge did not exist before life, though we can describe things that existed before life, and will exist after it.


To be sure, the things we typify as rose bushes and planets do exist in reality.

But the concept or type labelled “rose bush” or “planet” did not exist before life.

What about apparently eternal types such as “number” and “circle”?

If it were possible to destroy all minds and products of minds (including all computers).

Then all universal concept, types and descriptions (even “circle”) would disappear from the universe.


Doesn’t realism (rather than idealism) presume there is a mind-independent reality?

Scientific Idealism takes it as axiomatic that a mind-independent reality existed before there were minds.

The question is not about the nature of reality; it is about the nature of description.

Scientific Idealism is about the process of creating a description by idealisation - by classification or typification.

(This appears to be the defining characteristic of intelligence, both natural and artificial.)

And about the process of realising a description in a testable reality.


Wikipedia contrasts classical Realism and Idealism thus.

"Platonic realism: beauty is a property that exists in an ideal form independently of any mind or description.

Idealism: beauty is a property constructed in the mind, so exists only in descriptions of things."


Doesn’t idealism (rather than realism) presume there is no mind-independent reality?

There is no suggestion here that Scientific Idealism exactly matches the Idealism of Kant or Hegel.

However, Kant did contrast the phenomenal world, in which we live, and the noumenal world.

“The noumenal world exists only as a heuristic for our cognitive capacities.”


Science describes realities; conversely, realities that cannot be described can play no part in science.

The world is deeply mysterious, far beyond our direct understanding.

However, descriptions of that world (mental, document and other) are vital to our survival.

So, our knowledge of the world must be accurate enough to help us deal with it.


Scientific Idealism does not presume to draw the same description-reality distinction Kant did.

But it does distinguish descriptions from the realities they describe.

Science describes realities; conversely, realities that cannot be described can play no part in science.


The true nature of light is not directly accessible to us.

Light is modelled as either waves or particles in scientific descriptions.

But scientists don't actually believe light is either waves or particles in reality; those are only accurate enough descriptions.


A description is idealised from reality by one or more rational actors; it could not exist before life.

It exists in the sense it is held or encoded in at least one mental, documented or other model (which is itself part of reality).

Descriptions of the world can be accurate, inaccurate or somewhere in between.

We need descriptions that are accurate enough to be useful, to help us thrive and survive.

By "enough" I mean only - the description/model/proposition works - it passes those empirical tests we choose to judge its truth by


Is idealism incompatible with testing the accuracy or precision of models?

Scientific Idealism doesn't question whether reality exists independently of description.

It say that universals (and descriptions of any kind) are not mind-independent, are not eternal, do not exist outside of space and time.


"The realist school claims that universals are real—they exist and are distinct from the particulars that instantiate them."

“Realists tend to argue that universals must be posited as distinct entities in order to account for various phenomena.”

“... in denying that the eternal Forms are mental artifacts [this] differs sharply with modern forms of idealism.”

"Idealists, such as Kant and Hegel, posit that universals are not real, but are ideas in the mind of rational beings."


There is no external mind-independent standard against which to judge “accurate enough”.

How do we test the truth of descriptions based on universals like “circular” or Newton’s laws of motions?

We measure the values of qualities of realities (like Diameter, Force = Mass * Acceleration).


“As Einstein would have happily admitted [his] new physics was not a definitive answer, nor did it negate the importance of Newton’s contribution.

It was not “right” or “true”, but simply a more accurate explanation that Newton’s”, which was perfectly good for its time.

As a pragmatist would say, it was a valid explanation” Marcus Weeks

Newton's laws are accurate enough to pass such tests in the world we live in.


How do we test the truth "universals" like "beauty" and "good" when applies to a perceptible situation, entity or event?

We may measure them by asking people’s opinions in a survey of some kind.

Another way is to form a hypothesis that predicts the outcome of an entity being described as "beautiful" or "good".

The practical difficulty of the experiment, along with disinterest in trying, doesn't mean that testing is impossible.



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