Maverick Philosopher

Footnotes to Plato from the foothills of the Superstition Mountains

Our Knowledge of Existence: How Do I Know that a Thing Exists?

The following incomplete draft has been languishing on my hard drive, on a memory stick, and in 'the cloud' since late November 202o.  So I will post it now to see what comments Elliot C. (and anyone else) has to offer. In other threads he has shown a burning interest in this question.

………………………..

1) I see a tree, a palo verde.  Conditions are normal both inside and outside of me, the perceiver. My eyesight is 20/20, the lighting is good, etc. I see that the tree is green, blooming, swaying slightly in the breeze, and so on. I know (directly, i.e., in the temporal present, without reliance on memory or testimony or inference) that the tree has these and other properties, and I know this by sense perception, in this instance by seeing them, and indeed by seeing them without the aid of such instruments as binoculars or closed-circuit television.  I know that the tree is green by seeing that the tree is green.  But  I cannot see that the tree is green without seeing green at the tree.  So I know (directly) that the tree is green by seeing green at the tree. It follows that the property green is sense-perceivable. It is a sensible or observable property. 

2) I presumably also know that the tree exists by seeing it.  That is, my seeing the tree suffices for my knowing that it exists. And the birds in the branches? Likewise: I know that they exist by seeing them.  But while I cannot know (directly) that the tree is green without seeing green at the tree, I can presumably know that the tree exists without seeing existence at the tree. For whatever existence is, it is not a sensible or observable property.  I see the green of the tree, but not the existence of the tree. Green is observable; existence is not. If I do know that the tree exists by seeing it, how do I know this given that existence is not  a sensible or empirically observable property or feature of the thing that exists?

3) And so we have a puzzle that arises naturally just by reflecting on some obvious data.  The problem is expressible as an inconsistent pentad. The  following propositions are individually plausible, and yet they are collectively inconsistent. Something's got to give.  To solve the problem, we either reject or reformulate one or more of the propositions, or we argue that, despite appearances, the propositions are consistent.

a) I know that the tree exists.

b) I know that the tree exists by seeing  that it exists.

c) An individual exists by instantiating the property of existence.

d) If I see that a thing has a property, then I see the property at the thing.

e) One cannot see or otherwise sense-perceive the property of existence.

The five  propositions are (collectively) inconsistent. Any four of them, taken together, entails the negation of the remaining one.  For example, the conjunction of the first four entails the negation of (e).  So the only way to solve the problem is by rejecting/revising one or more of the limbs. But which one?  Given the high plausibility of (a), (b), and (e), the natural candidates for rejection are (c) and (d).

Response 1: The existence of an individual is  not a property it instantiates, but the individual itself.

Given that the pentad is inconsistent, one response to it is by rejecting (c) by rejecting a presupposition on which (c) rests, namely, that  existence is a property of individuals.  Suppose it is maintained instead that the existence of an individual is just that individual.  Thus the existence of the tree is just the tree; it is not a property of the tree. If so,  then there is no real, non-verbal, difference between the tree and its existence. A tree and an existent/existing tree are one and the same.  To see the tree would be to see its existence.  Equivalently, to see the tree would be to see an existing tree. If this is right, then the solution to the puzzle is straightforward: I know that the tree is green by seeing  green at the tree, and I know that the tree exists simply by seeing the tree.  Seeing a sense-perceptible thing suffices for knowing that it exists.  

Rebuttal of Response 1

To see what is wrong with this response, consider a different example. I am looking at the Sun. While I am looking at it, it ceases to exist. Since it takes about eight minutes for the light of the Sun to reach the Earth, the following could happen: the object-directedness of the perceptual act undergoes no modification despite the fact that the object, the Sun, has ceased to exist.  I continue for a few minutes to see something  — no seeing without seeing something — but the something I see no longer exists. This shows that one cannot infer the real or extra-mental existence of the accusative of an act from the accusative's givenness.  By the accusative of a mental act I mean that which appears to the mind in  the act. In my first example, the accusative is the tree precisely as seen.  The back side of the tree is not seen by me, and so it is not part of the accusative. And the same goes for the ant on the front side of the tree which I cannot see because of my distance from the tree. Of course, the tree in reality either has an ant on its front side or it does not.  The tree in reality cannot be indeterminate in this regard, or in any regard.  But the accusative, as such, is indeterminate in this regard. This is the fate of intentional objects generally qua intentional objects: they are incomplete. This incompleteness reflects the finitude of our minds.

In the second example the accusative is the Sun precisely  as seen by me here and now. Therefore, if by 'existence' we mean existence in reality or existence in itself or extra-mental existence — these being equivalent terms — then I cannot know that a perceptible thing exists simply by seeing it.  For it could be that the accusative does not exist at the time it appears. I see the Sun at a time when there is no Sun to be seen. Appearing and being (existing) fall asunder.

One can arrive at the same conclusion via the Cartesian dream argument. I see things in dreams  that don't exist or that no longer exist.  My use of 'see' here is obviously a phenomenological use.  On this use, 'see' is not a verb of success: 'S sees x' does not entail 'S exists.'  Phenomenologically, one can see and otherwise sense-perceive what does not exist. I  had an extremely  vivid lucid dream once in which I saw, heard, and touched a beloved cat that I knew was dead.  I SAW the cat (in the phenomenological sense of 'see') despite its nonexistence in reality.  I didn't remember the cat or imagine it:  I saw it. I had a visual experience as of a cat even though my eyes were closed.

Or suppose a mad neuroscientist so stimulates a brain in a vat that the brain gives rise to a visual perception as of a tree just like the one in my opening example.  (The brain is eyeless and is not connected to any optical transducers.) The accusative of the act is given but it does not exist in reality.  You could say that in a case like this the accusative enjoys esse intentionale but not esse reale.

The upshot is that one cannot know that a perceptible item such as tree exists by seeing it. So response 1 fails.

Response 2: One can know that a visually-perceptible thing exists without seeing that the thing instantiates the putative property of existence and without seeing a thing that is identical to its existence.  The existence of an individual does not belong to the individual.  

On this response, a presupposition of all five limbs of the pentad is called into question, namely, the notion that existence belongs to existing things as it would belong to them if it were either a property of them, or identical to them, or hidden within them, or in some other way 'at' them or 'in' them.  One way to deny this presupposition is by holding that the existence of a tree, say, is really a property of something else.  One might say that the existence of trees is a property of the world-whole, the property of containing trees.  To say that trees exist would then be to say that the world contains trees.  Existence would then be a mondial attribute: it would be a property of the world.  The existence of Fs is then just the world's having the property of containing Fs.   The existence of Socrates is just the world's containing Socrates.

Rebuttal of Response 2

The theory is explanatorily  circular and worthless for that reason. The world cannot contain Socrates unless Socrates exists.  Before (logically speaking) the world can contain Socrates, Socrates must exist. To explain the existence of Socrates by saying that the world has him as a member is to presuppose the very thing that needs explaining, namely, the existence of Socrates.  The circular is of embarrassingly short diameter.

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Bill Vallicella

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13 responses to “Our Knowledge of Existence: How Do I Know that a Thing Exists?”

  1. oz Avatar
    oz

    If I see that some is P, then by the same token I see that some SP exists. But it sounds strange to say that I see the existence of the SP. I think the problems you are having here are the result of treating existence as a property. I agree that ‘exists’ is a predicate, a linguistic item. But it is a predicate without a corresponding property.
    But you knew I was going to say that.

    Reply
  2. Elliott Avatar
    Elliott

    This is an interesting post, Bill.
    You’re talking about knowledge that, i.e., propositional knowledge. Is your position that propositional knowledge requires epistemic certainty? Or is propositional knowledge consistent with fallible justification? Does the pentad require you to take a position?
    I take it that “I know that the tree exists” is not a claim to know what the tree is, but only that it (whatever it is) exists. You are not committing yourself to the claim that the tree exists, say, as a physical object.
    Suppose we say knowledge requires epistemic certainty and that if one is epistemically certain that proposition p is the case, then given one’s evidence E for p, one cannot be wrong that p. E supports p at a probability of 1.
    How would something like this work?
    a) I know that the tree (whatever it is) exists.
    b) I know that the tree (whatever it is) exists by seeing that it exists.
    c) An individual exists by instantiating the property of existence.
    d) If I see that a thing (whatever it is) has a property, then I see the property at the thing.
    e) One cannot see or otherwise sense-perceive the property of existence.
    Support for (a) and (b): I am directly experiencing a tree (or some parts/aspects of it); I am being appeared-to-treely. I cannot be wrong that this visual experience is occurring, though the experience doesn’t prove what the tree is (say, that the tree is a physical object). I know with epistemic certainty that there is this experience, that is, the visual experience of a tree — whatever the tree is (for all I know, it might be a physical object; it might be a bundle of experienceable properties or tropes; etc.) Thus, I know via direct experience that there is something that is a tree, although I don’t know what that something is in itself. I don’t know that it is an extra-mental entity, for example.
    Support for (d): I am having a visual experience of the property green at the tree. I can’t be wrong that this experience is occurring and that it appears to me to be at the tree. I see (I visually experience) green at the tree (whatever the tree is).
    Plausibly, existence is not a (first-order) property. If this is right, (c) is false and (e) is true in the sense that one cannot see the property of existence because there is no such thing — assuming (c) and (e) are about first-order properties.
    Regarding your example of the Sun, perhaps what you experience are the present remnants of a past object that has ceased to exist. Or perhaps the Sun continues to exist because, say, eternalism or growing block theory is true rather than presentism.

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  3. BV Avatar
    BV

    Thanks, Elliot. It’s getting near bedtime, so I have time for only one comment.
    >>I take it that “I know that the tree exists” is not a claim to know what the tree is, but only that it (whatever it is) exists. You are not committing yourself to the claim that the tree exists, say, as a physical object.<< But surely trees are physical objects, and what I am looking at is a tree. And of course I believe that what I am looking at exists. The question is: how do I know that it exists where knowledge entails objective certainty? It is important to note that the following fails as an explication of existence: X exists iff X is a physical object. I have no doubt that what I am looking at is a physical object; The question is: how do I know that the physical object I am looking at exists. And of course to exist is to exist in reality, that is, extramentally and extralinguistically. Suppose that at ontological bottom everything is a physical thing. Even if this were true, which it is not, existence cannot be identified with physical thinghood. Even if everything is physical, it is not in virtue of its being physical that a physical thing exists. This is absolutely crucial, the "beginning of wisdom" in the theory of existence. To help you appreciate the point, note that 'X exists =df x is a physical thing' is true only x exists. But then the definition is circular, amounting to 'X exists iff x is a physical thing and x exists.' Just as existence cannot be reduced to any quidditative determination such as treeness, it cannot be reduced to any categorial determination such as physicality , or spatiality or temporality or whatever.

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  4. oz the ostrich Avatar
    oz the ostrich

    >To help you appreciate the point, note that ‘X exists =df x is a physical thing’ is true only x exists. But then the definition is circular, amounting to ‘X exists iff x is a physical thing and x exists.’< By equal reasoning, "X is lamb =df x is mutton" entails "X is lamb iff X is lamb and X is mutton". Which is true of course, but does not mean that the definition is circular. A definition gives the meaning of a word whose meaning is not known in terms of a word whose meaning is known.
    Of course, if the meaning of ‘physical thing’ is not known then there is a problem. Is that what you meant?

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  5. BV Avatar
    BV

    Hey Elliot, can you explain the point I made @7:30 to Oz?

    Reply
  6. Elliott Avatar
    Elliott

    Bill,
    I can give it a shot.
    This definition is inadequate because it’s circular:
    ‘X exists =df x is a physical thing.’
    Why is it circular? Because the definiendum shows up in the definiens. That x is a particular thing (e.g., a physical item) presupposes that x exists. Similarly, that x falls into a category of things (e.g., physical objects) presupposes that x exists. Hence, the existence of x can’t be defined in terms of its being a particular thing, whether a physical thing or some other kind of thing, nor can the existence of x be defined in terms of its falling into some category of existing things.
    By the way, I didn’t intend in my post above to suggest that existence is defined in terms of physicality. If I unintentionally suggested such, I should have been more clear.

    Reply
  7. David Brightly Avatar
    David Brightly

    Bill,
    You write that you have a palo verde tree in your backyard. On this basis alone I do not know that you have such a tree. If I visit your backyard I will see the tree and I will then know that you have such a tree. I will say to myself, ‘Bill’s palo verde exists’. To formulate this corroboration without using the verb ‘to exist’ is clumsy. ‘There is such a tree of which Bill writes’, perhaps, or ‘There is such a written-of-by-Bill tree. So ‘to exist’ plays a role in expressing verification by acquaintance of an existence claim given by description. It’s part of the language around the corroboration of descriptive existence claims. In the clumsy ‘there is…’ formulations there is explicit linguistic ascent, viz, reference to something written by Bill. If the ‘there is…’ and the ‘…exists’ formulations are synonymous they must both contain linguistic ascent. So any noun phrase governing ‘exists’ has to be thought of as a reference to an earlier existence claim, possibly implicit, which the reader/listener may reasonably be holding in doubt. This may go some way towards explaining the difficulty of defining ‘exists’.
    The standard understanding of ‘knowledge’ leaves out an important psychological factor. When we acquire knowledge by acquaintance we move from a state of ignorance or reasonable doubt to a state of relative confidence in a claim, typically sufficient for appropriate action. You mention a number of factors that can diminish confidence:

    1. finite propagation speed of light, sound, smell from distant events
    2. perceptual error and dreaming
    3. deliberate deception
    4. brain in vat scenario
    5. metaphysical undermining

    We live each day with (1)–(3) and guard against them. We encounter (4) and (5) only when philosophising. For (1)–(3) we can readily demarcate between circumstances in which they may and may not occur, and we have precautionary or corrective measures against them. We can hedge our claims with reference to signal travel time intervals, say, ensure adequate illumination, dismiss dreamed experience, be suspicious and careful, use multiple senses, and so on. We are not ‘in the dark’, as it were, with respect to perceptual mistakes. Putting these out-of-the-ordinary situations to one side we are left with common sense knowledge acquired through the senses. (4) and (5), however, can be utterly undermining of common sense. We are left feeling that we do not understand the meaning of ‘know’. But if, in the ordinary world, after due care I see the palo verde in your backyard, then I know there is a palo verde in your backyard. This is just understanding how to use the word ‘know’.

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  8. BV Avatar
    BV

    Elliot,
    You get my point. But why doesn’t Oz get it?
    You wrote, >>You are not committing yourself to the claim that the tree exists, say, as a physical object.<< You have since clarified your position, but this suggested to me that you are sharing Oz's view that if my tree does not exist, then it is not a physical object.

    Reply
  9. BV Avatar
    BV

    Thanks for the comment, David. If I don’t answer all your comments or e-mail that is because I am pressed for time.
    >>If the ‘there is…’ and the ‘…exists’ formulations are synonymous they must both contain linguistic ascent. So any noun phrase governing ‘exists’ has to be thought of as a reference to an earlier existence claim, possibly implicit, which the reader/listener may reasonably be holding in doubt.<< The two formulations are only sometimes synonymous. 'There is an honest man' and 'An honest man exists' are synonymous. They are both general existence claims, general existentials. 'Aristides exists,' however, is a singular existential. I have given several arguments to show that singular existentials cannot be reduced to general existentials. Suppose I give my tree the name 'Pal.' 'Pal' is a proper name, not a noun phrase. and it does not, contrary to what you say, have to be thought of as referring to an earlier claim, existential or not. I see Pal. I say 'Pal is in bloom.' Then I THINK: if if Pal is in bloom, then Pal exists, And then I wonder: how do I know that Pal exists? The rest of what you say, David, is very commonsensical and adequate for all practical purposes. And of course we all know how to use 'know' in the commonsense way. But these commonsense points leave the epistemological question untouched.

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  10. Elliott Avatar
    Elliott

    If I may elaborate, there’s a difference between the pragmatic semantics of ‘knowledge’ and the epistemological investigation into the nature of knowledge. Discussion of how folks use ‘know’ in various contexts leaves untouched the epistemological question of what knowledge is. This is one of the problems with epistemic contextualism (EC) – or so it seems to me. EC is a semantic thesis about what people mean by ‘knowledge’ in different linguistic contexts. EC does not directly address the dispute between skeptics and anti-skeptics regarding the nature of knowledge (the thing itself, not the word). Skeptics and anti-skeptics are concerned with what knowledge is, and not so much with what words such as ‘knowledge’ and ‘know’ mean in different linguistic contexts.
    People use words with varying degrees of precision in different situations. For example, I might say that Florida is flat. In ordinary language, the point is understandable. But of course, Florida is not precisely flat, and I am not addressing the nature of flatness if I say that Florida is flat. Similarly, people use ‘know’ in multifarious ways — some more precise, and some far less precise — but that fact doesn’t tell us much about what knowledge is in itself.

    Reply
  11. David Brightly Avatar
    David Brightly

    Thank you for the reply, Bill. I confess I struggle to see a problem here. The meanings of ‘existing’, ‘seeing (sensing)’, and ‘knowing’ seem to me to form an interrelated nexus that cannot be further decomposed. How do you know that Pal exists? You see(sense) it. What other answer could there be?

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  12. BV Avatar
    BV

    Elliot,
    I agree with your comment.
    David writes, >>How do you know that Pal exists? You see(sense) it. What other answer could there be?<< You are assuming that one cannot see something that does not exist. I grant that 'see' is standardly used as a verb of success, i.e., necessarily, if S sees x, then x exists. On this use of 'see' it is impossible to see something that doesw not exist. But there is also a phenomenological use of 'see' that does not entail existence. I don't know about you, but I see things in my dreams. No vat needed!

    Reply
  13. David Brightly Avatar
    David Brightly

    Bill, my visual experience during dreams is highly impoverished compared with my waking experience. Since childhood I have always been able to tell dreaming from waking, and I have never had anything approaching your cat dream experience. Hence I think that real and illusory visual experiences are well separated.

    Reply

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