• Art48
    459
    An abstract object is defined as something which is neither spatial nor temporal: an abstract object does not exist in space and time. (“Object” should not be taken too literally; think “abstract entity.”) A typical example of abstract objects is numbers. Numbers such as 2 or π do not exist in space/time. Yes, two apples exist in a particular place at a particular time; but the number 2 itself does not.

    Seeing that nearly all the words to be found in the dictionary stand for universals, it is strange that hardly anybody except students of philosophy ever realizes that there are such entities as universals. – Bertrand Russell, The Problems of Philosophy, Chapter IX. The World of Universals

    What Russell said of universals may be said of abstract objects. (The two concepts are similar or even identical, depending on the definition used.) If nearly all the words found in the dictionary stand for abstract objects, then it follows that our experience consists almost exclusively of abstract objects, as I’ll show.

    Let’s begin with perception. I experience the physical world though my five senses: sight, taste, touch, hearing, and smell. I do not possess a special “tree-sensing” sense. So how can I experience a tree? The answer is I do not directly experience the tree. Rather, my eyes see patches of brown and green; my fingers tell me the brown patches are rough and the green patches are smooth. My mind retrieves the idea “tree” to explain what my senses are telling me. Tree is a mental representation which describes what I experience. (We may suppose a newborn infant only sees patches of light. Over time, the infant deduces the ideas of object, object permanence, and eventually tree.)

    There’s a wonderful example which illustrates, Adelson’s Checker-Shadow Illusion (refer https://www.illusionsindex.org/ir/checkershadow). The two squares labeled A and B are the same color! To convince myself, I had to print the illusion, cut out the squares and put them side by side. Yet, even after doing that, I still see the two squares as being two different colors.

    When I look at the illusion, I do not see what my eyes see. Rather, I am seeing what my mind creates based on what my eyes see. Our mind’s automatic processing is a wonderful evolutionary advantage. For survival, seeing some orange, black, and white stripes is far inferior to seeing a tiger. But we have no tiger-sensing sense.

    We can directly see on only one thing: light. The mind does the rest. Almost everything we experience though our senses are universals, are abstract objects, are ideas in our mind.

    It is strange that the existence of abstract objects is sometimes questioned when abstract objects comprise the bulk of what we experience. Abstract objects have a more certain ontological foundation than physical objects. We experience rough brown patches and smooth green patches. Of that experience we can be absolutely certain. We naturally suppose something in the physical universe called a “tree” is the cause of what we experience. Of that we can be almost certain.

    A “brain in a vat” experiences rough brown patches and smooth green patches. Of that experience the brain can be absolutely certain. The brain naturally supposes something in the physical universe called a “tree” is the cause of what we experience. It is wrong.

    My mind directly experiences the number two because the number two is a thought and my mind experiences thoughts directly. Similarly, my mind can directly experience the abstract object named “tree” because that, too, is a thought. As to what is causing my experiences, I suppose there’s a material object, a material tree, existing in a physical universe outside myself. If I’m not dreaming, hallucinating, or a brain in a vat, then my supposition may be correct. There may actually be a material tree, existing in a physical universe outside myself. But, then again, there might not.

    Instead of questioning the existence of abstract object, perhaps we should apply our skepticism the existence of an exterior physical universe.
  • Harry Hindu
    4.9k
    Let’s begin with perception. I experience the physical world though my five senses: sight, taste, touch, hearing, and smell. I do not possess a special “tree-sensing” sense. So how can I experience a tree? The answer is I do not directly experience the tree.Art48
    What does it even mean to "directly" or "indirectly" experience something?

    An abstract object is defined as something which is neither spatial nor temporal: an abstract object does not exist in space and time. (“Object” should not be taken too literally; think “abstract entity.”) A typical example of abstract objects is numbers. Numbers such as 2 or π do not exist in space/time. Yes, two apples exist in a particular place at a particular time; but the number 2 itself does not.Art48

    We can directly see on only one thing: light. The mind does the rest. Almost everything we experience though our senses are universals, are abstract objects, are ideas in our mind.Art48
    Then the two particular apples are also universals?

    My mind directly experiences the number two because the number two is a thought and my mind experiences thoughts directly. Similarly, my mind can directly experience the abstract object named “tree” because that, too, is a thought. As to what is causing my experiences, I suppose there’s a material object, a material tree, existing in a physical universe outside myself. If I’m not dreaming, hallucinating, or a brain in a vat, then my supposition may be correct. There may actually be a material tree, existing in a physical universe outside myself. But, then again, there might not.Art48
    How did you come to know the number 2 if not by seeing the scribble, "2" and seeing two of something, like seeing two apples? Are the scribbles on this screen directly or indirectly experienced?

    It seems to me that universals stand for all the existing things in that set, and by "existing" I mean that they have causal power.

    Is your idea of a cat an abstract or concrete thing? It is abstract when it is understood to exist in the same way as what it is meant to represent. Does the idea, "cat" exist in the same way as a physical cat? It is concrete if understood to exist in the world and is just as real as what it represents. Is your actual experience of cats just as real as the cat that is experienced, and is just as much part of the world as a physical cat? What are you talking about when you talk about your experiences. Are you talking about something abstract or something concrete? I'm not asking about what your experiences are of. I'm talking specifically about your experiences. What about your dreams? I'm not asking about dreams in the abstract. I'm asking specifically about your dream - a specific dream that you had. Is a specific dream that you had a member of the abstract object, "dreams"?
  • Art48
    459
    “What does it even mean to "directly" or "indirectly" experience something?”

    An analogy: Imagine indirect experience as watching a baseball game on TV, as opposed to being in the park. We don’t directly experience the tree; our senses play the role of TV.


    “Then the two particular apples are also universals?”

    Apple is a universal. A particular apple is an instantiation of the universal called “apple”.


    “How did you come to know the number 2 if not by seeing the scribble, "2" and seeing two of something, like seeing two apples?”

    We become acquainted with some universals by seeing particulars. We see two apples, two trees, two people and see an abstract similarity which we call “two”. The abstract similarity is a universal which we perceive with our mind, not our five senses.


    “It seems to me that universals stand for all the existing things in that set . . . “

    Without the idea of two, we cannot apply the idea of two to a pair of apples. Example, I define “xyz” as the set of all xyz things. Not a very useful definition.

    Moreover, the set of all existing two things is constantly changing. If I eat one of the two apples, then the “set of all existing two things” has changed. If two atoms are crushed out of existence in some neutron star in another galaxy, the “set of all existing two things” has changed.


    “Does the idea, "cat" exist in the same way as a physical cat?”

    Ideas exist in the “mindscape.” Physical cats exist in the physical world.


    “What are you talking about when you talk about your experiences. Are you talking about something abstract or something concrete?”

    Experience is concrete. I physically experience rough brown patches and smooth green patches, which lead me to mentally experience a universal, i.e., the idea of a tree.
  • T Clark
    13k
    A good OP. Well-written, clear, and interesting.

    If nearly all the words found in the dictionary stand for abstract objects, then it follows that our experience consists almost exclusively of abstract objects, as I’ll show.Art48

    I think you've put the cart before the horse. Not nearly all, but all words in the dictionary stand for abstract objects because naming things is what makes them abstract objects. We overlay an abstract coating on the world as it is. We create the abstract world. "Tree" is no less abstract than "2," even though it refers to that tall thing out in my yard. Actually, "that tall thing out in my yard" is abstract too.

    So how can I experience a tree? The answer is I do not directly experience the tree.Art48

    I go back and forth on this, but I think maybe we can directly experience a tree. You don't need to say "tree," even in your mind, when you see one. I don't think you can see one completely unmediated. I'm not sure how close we can come to that.

    We can directly see on only one thing: light. The mind does the rest.Art48

    It's my understanding that aspects of perception sometimes come before the mind, e.g. I read that the eye is constructed in such a way that it processes the sight before it gets to our minds.

    A “brain in a vat” experiences rough brown patches and smooth green patches. Of that experience the brain can be absolutely certain. The brain naturally supposes something in the physical universe called a “tree” is the cause of what we experience. It is wrong.Art48

    I'm not sure we know what a hypothetical brain in a vat experiences. Saying that something in the physical world called a tree is the cause of my experience is not wrong, it is part of the definition of the word "cause," which I'm sure we'll agree is an abstract entity.

    My mind directly experiences the number two because the number two is a thought and my mind experiences thoughts directly. Similarly, my mind can directly experience the abstract object named “tree” because that, too, is a thought. As to what is causing my experiences, I suppose there’s a material object, a material tree, existing in a physical universe outside myself. If I’m not dreaming, hallucinating, or a brain in a vat, then my supposition may be correct. There may actually be a material tree, existing in a physical universe outside myself. But, then again, there might not.Art48

    This is all very philosophical and presumptuous, which, like "abstract" and "universal," often mean just about the same thing.

    Instead of questioning the existence of abstract object, perhaps we should apply our skepticism the existence of an exterior physical universe.Art48

    There's a thread out there doing that right now. I've avoided it. Seems like a pointless exercise.

    As I said, good OP.
  • NOS4A2
    8.3k


    If you experience the world through the five senses, what being and with what kind of senses do you experience abstract objects?
  • Agent Smith
    9.5k
    In the physical world, 2 and tree are very different - one is visible, can be touched, smelt, tasted, and so on while the other cannot.

    In the mental world, however, these dissimilarities are attenuated, some might say even completely obliterated.
  • Art48
    459
    NOS4A2: If you experience the world through the five senses, what being and with what kind of senses do you experience abstract objects?

    The mind.Abstract objects are ideas.
  • Bartricks
    6k
    The mind is not a sense.
    Ideas are always the ideas of a mind. That seems undeniable. And minds seem able to be aware of their own mental states by means of a faculty of introspection.
    So when you say that abstract objects are ideas, then they are not objects, but states of a mind (for minds alone have ideas). And we are aware of them via a faculty - the faculty we call introspection (which is a misleading name as it implies it essentially detects only one's own mental states).
    Would that be correct?
  • NOS4A2
    8.3k


    Isn’t the mind, too, an abstract object? An idea? How do we experience abstract objects with other abstract objects, ideas with other ideas?
  • Art48
    459
    T Clark: A good OP. Well-written, clear, and interesting.
    Thanks.

    T Clark: We overlay an abstract coating on the world as it is.
    I’d say we overlay an abstract coating on what our senses tell us, but as to the thing-in-itself or the world as it is, we have only the indirect evidences of our sense data.

    T Clark: This is all very philosophical and presumptuous, which, like "abstract" and "universal," often mean just about the same thing.
    True I’m stating a philosophical position, but I wouldn’t call it presumptuous.

    Bartricks: The mind is not a sense.
    We see trees in the “landscape” with our eyes. We see ideas in the “mindscape” with our minds.

    Bartricks: for minds alone have ideas
    I’m taking the position that ideas exist independent of minds. Otherwise, if our minds create the ideas then if you and I discuss the number 2, we are discussing two different things: the number 2 that your mind creates and the number 2 that my mind creates. But if the number 2 exists independently, then we can discuss a single topic, i.e., the number 2.

    NOS4A2: Isn’t the mind, too, an abstract object?
    Just as sight is an abstract object but seeing itself is a sense, I’d say the mind can be thought of as an abstract object, but the mind in action, encountering thoughts, is a sense.
  • Janus
    15.5k
    Let’s begin with perception. I experience the physical world though my five senses: sight, taste, touch, hearing, and smell. I do not possess a special “tree-sensing” sense. So how can I experience a tree? The answer is I do not directly experience the tree. Rather, my eyes see patches of brown and green; my fingers tell me the brown patches are rough and the green patches are smooth. My mind retrieves the idea “tree” to explain what my senses are telling me. Tree is a mental representation which describes what I experience. (We may suppose a newborn infant only sees patches of light. Over time, the infant deduces the ideas of object, object permanence, and eventually tree.)Art48

    I think this is too simplistic; it might stand out against the sky, I see many others like it and many others very different, you can climb the tree and gain another view on the landscape, you can smack into it bodily, pluck leaves and cut limbs off, you can move around it and view it from all sides, you can find shade or shelter from the rain under it or if it is large enough, even build a house in it, It is not merely a matter of "brown patches and green", although that might be part of it, it is questionable whether that will be the first thing we notice, and everyone is different, anyway.
  • Richard B
    365
    Physical objects and Abstract objects, what do these two things have in common that we want to call them objects? A shared essence or some family resemblance? Hard to say it is either.
  • Wayfarer
    20.7k
    I experience the physical world though my five senses: sight, taste, touch, hearing, and smell. I do not possess a special “tree-sensing” sense. So how can I experience a tree? The answer is I do not directly experience the tree. Rather, my eyes see patches of brown and green; my fingers tell me the brown patches are rough and the green patches are smooth. My mind retrieves the idea “tree” to explain what my senses are telling me. Tree is a mental representation which describes what I experience. (We may suppose a newborn infant only sees patches of light. Over time, the infant deduces the ideas of object, object permanence, and eventually tree.)Art48

    :up: Agree. Most modern philosophy forgets this fact.

    By the way - to quote someone's post, select the text you want to quote and then click or tap the 'Quote' button which will hover above it. It will make the conversation easier to follow.

    sqyhzhbx5airssg5.jpg
  • Agent Smith
    9.5k
    I have no further comment on abstract objects, but I do have something to say about all these purported "illusions" the mind creates. If the mind does do this, then everything is suspect vis-à-vis their reality including the so-called truth which is revealed later on. Oui?

    Secondly, the generalization from such "illusions" is dubious - just because of a few examples of perceptual illusions, it doesn't imply the world itself is an illusion à la maya or Plato's cave allegory. Going from local to global, bad move sir/ma'am! :snicker:
  • litewave
    801
    An abstract object is defined as something which is neither spatial nor temporal: an abstract object does not exist in space and time.Art48

    But if the mind is identical to the brain (or to some parts of the brain), then the mind, and everything in it, is spatiotemporal and therefore not abstract but concrete. We can't visualize an abstract tree because we can only visualize spatial objects. What might seem as the experience of an abstract tree is the experience of a typical or usual concrete example of a tree, associated with a concrete sound of the word "tree" or a concrete mark of the written word "tree", and associated with other concrete examples of a tree that trigger similar concrete visual experiences. This way however, we may at least indirectly experience an abstract tree - through experience of concrete objects and their concrete causal associations in the brain.
  • Art48
    459
    I have no further comment on abstract objects, but I do have something to say about all these purported "illusions" the mind creates. . . . Secondly, the generalization from such "illusions" is dubious -Agent Smith

    “Illusion” suggests what I experience is unreal, a misapprehension. It suggests something that occurs occasionally.

    I have only five physical senses. Based on my sense input, ideas arise in my mind. My sense input is real. The idea in my mind really exists and is an attempt to model what is stimulating my physical senses.

    The process occurs not occasionally, but rather at all times throughout my life, from when I acquire object permanence at a few months of age to death.to death.

    I experience the properties of the unknown thing-in-itself one way; other beings (such as the color-blind person) may experience the unknown thing-in-itself differently. But that doesn’t mean I misapprehend the thing.

    So, I don't think “illusion” is appropriate.

    This way however, we may at least indirectly experience an abstract tree - through experience of concrete objects and their concrete causal associations in the brain.litewave

    Our five physical senses limit us to experiencing sight, sound, taste, touch, and smell. So, we don’t directly experience concrete objects. (I have no special “tree-sensing” sense with which I can directly experience a tree.)

    The tree (which you refer to as the “abstract tree”) is an idea I experience in our mind; it what my mind really experiences.

    A somewhat similar situation is that when you watch a TV or computer monitor, all you can see is light. But based on the light you see, your mind experiences ideas such as people, sand, ocean, clouds, etc.
  • litewave
    801
    Our five physical senses limit us to experiencing sight, sound, taste, touch, and smell. So, we don’t directly experience concrete objects.Art48

    We directly experience the brain, which is a concrete object in space and time.
  • Richard B
    365
    “Our five physical senses limit us to experiencing sight, sound, taste, touch, and smell. So, we don’t directly experience concrete objects. (I have no special “tree-sensing” sense with which I can directly experience a tree.)”

    What could this mean “we don’t directly experience concrete objects” I see a tree, I go over to touch the leaves, smell the bark, hear the creaking of the branches, or taste the fruit it produces. How more direct can we get?
  • Art48
    459
    What could this mean “we don’t directly experience concrete objects” I see a tree, I go over to touch the leaves, smell the bark, hear the creaking of the branches, or taste the fruit it produces. How more direct can we get?Richard B

    Suppose you see a hurricane on TV. You directly experience the TV's light and sound; you indirectly experience the hurricane. Similarly, you indirectly experience the tree; you directly experience light, sound, touch, taste, odor. The idea is similar to the "brain in a vat" thought experiment (which was the basis for the movie The Matrix).
  • Banno
    23.4k
    I suggest reading Austin's "are there a priori concepts?". It is the third paper in a symposium. Jstore has it. Austin's criticism of "universal" concepts starts at about p.84.

    Bowdlerising his argument, it simply is not the case that the grey of a cloud and the grey of this laptop have something in common - apart from our use of the word "grey". Or if you prefer, abstract objects do not exist.
  • Tom Storm
    8.4k
    Austin's criticism of "universal" concepts starts at about p.84.Banno

    Cool. I'll go look.
  • Wayfarer
    20.7k
    Brief defense of universals, bolds added.

    As a matter of fact, if any one were anxious to deny altogether that there are such things as universals, we should find that we cannot strictly prove that there are such entities as qualities, i.e. the universals represented by adjectives and substantives, whereas we can prove that there must be relations, i.e. the sort of universals generally represented by verbs and prepositions.

    Let us take in illustration the universal whiteness. If we believe that there is such a universal, we shall say that things are white because they have the quality of whiteness. This view, however, was strenuously denied by Berkeley and Hume, who have been followed in this by later empiricists. The form which their denial took was to deny that there are such things as 'abstract ideas '. When we want to think of whiteness, they said, we form an image of some particular white thing, and reason concerning this particular, taking care not to deduce anything concerning it which we cannot see to be equally true of any other white thing. As an account of our actual mental processes, this is no doubt largely true. In geometry, for example, when we wish to prove something about all triangles, we draw a particular triangle and reason about it, taking care not to use any characteristic which it does not share with other triangles. The beginner, in order to avoid error, often finds it useful to draw several triangles, as unlike each other as possible, in order to make sure that his reasoning is equally applicable to all of them.

    But a difficulty emerges as soon as we ask ourselves how we know that a thing is white or a triangle. If we wish to avoid the universals whiteness and triangularity, we shall choose some particular patch of white or some particular triangle, and say that anything is white or a triangle if it has the right sort of resemblance to our chosen particular. But then the resemblance required will have to be a universal. Since there are many white things, the resemblance must hold between many pairs of particular white things; and this is the characteristic of a universal. It will be useless to say that there is a different resemblance for each pair, for then we shall have to say that these resemblances resemble each other, and thus at last we shall be forced to admit resemblance as a universal. The relation of resemblance, therefore, must be a true universal. And having been forced to admit this universal, we find that it is no longer worth while to invent difficult and unplausible theories to avoid the admission of such universals as whiteness and triangularity. ...

    It is largely the very peculiar kind of being that belongs to universals which has led many people to suppose that they are really mental. We can think of a universal, and our thinking then exists in a perfectly ordinary sense, like any other mental act. Suppose, for example, that we are thinking of whiteness. Then in one sense it may be said that whiteness is 'in our mind'. ... In the strict sense, it is not whiteness that is in our mind, but the act of thinking of whiteness. The connected ambiguity in the word 'idea', which we noted at the same time, also causes confusion here. In one sense of this word, namely the sense in which it denotes the object of an act of thought, whiteness is an 'idea'.

    Hence, if the ambiguity is not guarded against, we may come to think that whiteness is an 'idea' in the other sense, i.e. an act of thought; and thus we come to think that whiteness is mental. But in so thinking, we rob it of its essential quality of universality. One man's act of thought is necessarily a different thing from another man's; one man's act of thought at one time is necessarily a different thing from the same man's act of thought at another time. Hence, if whiteness were the thought as opposed to its object, no two different men could think of it, and no one man could think of it twice. That which many different thoughts of whiteness have in common is their object, and this object is different from all of them. Thus universals are not thoughts, though when known they are the objects of thoughts.
    Bertrand Russell, World of Universals

    Consider that when you think about triangularity, as you might when proving a geometrical theorem, it is necessarily perfect triangularity that you are contemplating, not some mere approximation of it. Triangularity as your intellect grasps it is entirely determinate or exact; for example, what you grasp is the notion of a closed plane figure with three perfectly straight sides, rather than that of something which may or may not have straight sides or which may or may not be closed. Of course, your mental image of a triangle might not be exact, but rather indeterminate and fuzzy. But to grasp something with the intellect is not the same as to form a mental image of it. For any mental image of a triangle is necessarily going to be of an isosceles triangle specifically, or of a scalene one, or an equilateral one; but the concept of triangularity that your intellect grasps applies to all triangles alike. Any mental image of a triangle is going to have certain features, such as a particular color, that are no part of the concept of triangularity in general. A mental image is something private and subjective, while the concept of triangularity is objective and grasped by many minds at once.Edward Feser
  • Marchesk
    4.6k
    They don't have the shade of gray in common?

    Let's try a harder one. Do two electrons have the same charge in common? Is the problem with the phrase, "in common"? So two electrons have the same charge, but it's not in common?
  • Wayfarer
    20.7k
    I will say that it is perfectly true that universals do not exist, but Russell adds this tantilising qualification to his discussion:

    We shall find it convenient only to speak of things existing when they are in time, that is to say, when we can point to some time at which they exist (not excluding the possibility of their existing at all times). Thus thoughts and feelings, minds and physical objects exist. But universals do not exist in this sense; we shall say that they subsist or have being, where 'being' is opposed to 'existence' as being timeless. The world of universals, therefore, may also be described as the world of being. — Russell, World of Universals

    In that sense, universals don't exist, but are the structures within reason that enable the mind to discern general truths about the world. I like to think of them as the ligatures of reason.
  • Banno
    23.4k
    First, did you have a read of Austin's article? I think your questions might be addressed thereby.
  • Marchesk
    4.6k
    So I have to do homework in these threads now? I can't just react?
  • Tate
    1.4k
    Instead of questioning the existence of abstract object, perhaps we should apply our skepticism the existence of an exterior physical universe.Art48

    We can't really do without either of them, so skepticism is just a fun pastime.
  • Janus
    15.5k
    Bowdlerising his argument, it simply is not the case that the grey of a cloud and the grey of this laptop have something in common - apart from our use of the word "grey".Banno

    That's just not true, though; they each reflect light at wavelengths closer to each other than objects of other colours do compared to them, and consequently they look more similar to each other in terms of colour than objects of other colours do compared to them. The first is a material condition of the second and the second is the reason we refer to both as being grey, for our use of the word "grey".
  • Agent Smith
    9.5k
    @Art48

    It seems I do have something more to say about so-called abstract objects. Can you give me an example, one will do, of a pure abstract object and by that I mean an (abstract) object that has no links whatsoever with the physical world? It should exist only in the mind is what I'm saying.
  • Tate
    1.4k


    Abstract objects don't "exist" in any particular mind. Pi is an abstract object. It's not a resident of my mind in the way my grocery list is. I can't be wrong about my grocery list. I can be wrong about pi. It's that sort of thing.
  • Metaphysician Undercover
    12.4k
    Bowdlerising his argument, it simply is not the case that the grey of a cloud and the grey of this laptop have something in common - apart from our use of the word "grey". Or if you prefer, abstract objects do not exist.Banno

    It seems Marchesk prefers to use the word "gray". Do you think that the use of the word "grey", and the use of the word "gray" have something in common?
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