Talk:TheExistenceOfPhysicalObjects

In the main article I was trying to explain some of the main traditional lines of argument about this topic. To my knowledge, which might possibly be inadequate, what is below really is not part of that tradition (unless you'd want to rewrite it to make it reflect Berkleyan idealism). Let me reply to some of it (since I'm very interested in this topic these days, it so happens, on a professional level--i.e., I have a Ph.D. in philosophy and I have been reading journal articles on the subject, and writing and thinking about it to myself).

A further argument for the definability of existence is a corollary and extension of the philosophy of perception.

The philosophy of perception is a subject matter, and consequently doesn't by itself have any corollaries (as though it were a theorem or an axiom).

That is, if it can be perceived with the physical senses, then it exists.

Is this esse is percipi all over again--see George Berkeley.

Well, what makes a thing perceptible? The quality or property which makes a thing perceptible is that it is capable of affecting and of being affected. This is how one

perceives; one either creates an effect and receives the sensory feedback of having done so, or one witnesses the result of an effect created. When light reflects from a big, red apple, it is because the apple was capable affecting the light so as to alter its direction and absorb certain wavelengths while reflecting others. Consequently, the eye is able to detect the altered light and identify its new properties.

Hence, otherwise invisible energies and particles can be confirmed to exist by the effects they suffer or create. Magnetism, gravity, ultraviolet light, cosmic rays, all are included within the realm of existing things.

Here you are addressing a different problem from the one raised in the article; the name of your topic now is scientific realism, and that is the question whether the unusual theoretical ("unobservable" for example) entities posited by science are real, and what it might mean to say that they are real or exist. The question at issue in TheExistenceOfPhysicalObjects is "simpler" or more fundamental: what does it mean to say that anything exists at all? What does it mean to say that the eye, sensory feedback, and other physical objects exist? Perhaps, many philosophers say, existence isn't a property at all; in which case we shouldn't expect to be able to give a definition of 'exists', at least not a "first-level" definition (this isn't something I mentioned in the article...I could have done a better job with it, but I was writing for undergraduates who had never thought about this stuff before).

Taken further; since awareness, emotions, imagination, dreams, etc. are likewise capable of affecting and being affected, they could be said to exist.

So:

X exists if, and only if, X is capable of affecting and being affected.

So how do we decide that something exists? Why, we ask whether it is capable of affecting and being affected. Well, how do we determine whether something is capable of affecting and being affected?

One might say "I feel sadness." It could hardly be argued that sadness does not exist and so the person, contrary to his assertion, could not possibly feel sadness. Clearly, he does. The nature of the existence these intangibles is qualified and quantified by the nature of the effects they create and receive. Thus, unicorns could be said to enjoy a form of existence. They exhibit an imaginary existence. One imagines them, conveys the substance of this imagined existence to others, and thereby affects the imaginations of others to replicate said existence in their own imaginations. When a child learns from adults that there are no physically existing unicorns, his imaginary unicorns may lose their appeal or suffer destruction. This imposition of effect by physical existence on imaginary existence can also work in the reverse. An artist may "imagine" a finished canvas. Absent this precursor, imaginary existence, the physical canvas might never exist.

It seems to me you've refuted yourself. We're looking for a definition of the existence of physical objects. If, according to your definition, unicorns exist, since they don't in fact exist, your definition is wrong. Now, you can play semantic games and say that they enjoy "imaginary existence"; you can say whatever you want, but what difference does it make?

Sorry - I misuse the term "corollary."

I borrow from Hume:

This text is in the PUBLIC DOMAIN

?All reasonings concerning matter of fact seem to be founded on the relation of Cause and Effect. ... The hearing of an articulate voice and rational discourse in the dark assures us of the presence of some person: Why? because these are the effects of the human make and fabric, and closely connected with it. If we anatomize all the other reasonings of this nature, we shall find that they are founded on the relation of cause and effect, and that this relation is either near or remote, direct or collateral. ... When it is asked, What is the nature of all our reasonings concerning matter of fact? the proper answer seems to be, that they are founded on the relation of cause and effect. ... It may, therefore, be a subject worthy of curiosity, to enquire what is the nature of that evidence which assures us of any real existence and matter of fact, beyond the present testimony of our senses, or the records of our memory. ... Sight or feeling conveys an idea of the actual motion of bodies; but as to that wonderful force or power, which would carry on a moving body for ever in a continued change of place, and which bodies never lose but by communicating it to others; of this we cannot form the most distant conception. But notwithstanding this ignorance of natural powers and principles, we always presume, when we see like sensible qualities, that they have like secret powers, and expect that effects, similar to those which we have experienced, will follow from them. ... Now whatever is intelligible, and can be distinctly conceived, implies no contradiction, and can never be proved false by any demonstrative argument or abstract reasoning a priori. ... We have said that all arguments concerning existence are founded on the relation of cause and effect; that our knowledge of that relation is derived entirely from experience; ... The existence, therefore, of any being can only be proved by arguments from its cause or its effect? ...

I am afraid I, like Hume, blurred the line somehat between physical objects and less tangible things, but he tended (as one might expect from his time) to speak in rather concrete terms and to dwell in specific physical reality (while seeming to hold that thoughts, though ephemeral, were real and existed in no different wise than physical objects). Perhaps I would have done better not to stray into the realm of thought. However, his argument for the definability of existence (including the existence of physical objects) is not location in space, but Cause and Effect. And I happen to like his argument better. It was this argument I thought to exposit in more modern terms, to add to the arguments for the definability of the existence of physical objects.

In fact, Hume is famous for his view that existence is not a property and is therefore not definable. Careful not to confuse evidence for existence with whatever it is that constitutes a thing's existence.

I also think you're ignoring my main point, that this article should not be a collection of random opinions about the topic, but a clarification of the main lines of thought that can be found in the philosophical tradition. I don't see your point in the philosophical tradition.

I respect your ability and intelligence, but the issue I'm raising here isn't at all a commentary on that, of course!

I've removed your paragraphs. I would be very annoyed if anyone did this to me, so let me explain.

A further argument for the definability of existence could be seen as an extension of the philosophy of perception.

I probably didn't make the point clearly enough last time: the philosophy of perception is a philosophical subdiscipline about which there are many conflicting views (of course). So it doesn't make much sense to say that any controversial thesis is "an extension of" a philosophical subdiscipline.

> That is, if it can be perceived with the physical senses, then it exists. Well, what makes a thing perceptible? The quality or property which makes a thing perceptible is that it is capable of affecting and of being affected. This is how one perceives; one either creates an effect and receives the sensory feedback of having done so, or one witnesses the result of an effect created. When light reflects from a big, red apple, it is because the apple was capable affecting the light so as to alter its direction and absorb certain wavelengths while reflecting others. Consequently, the eye is able to detect the altered light and identify its new properties. Absent the existence of the apple, no effects would be created. That effects are created by it, and that one may affect it (say, cut up and eat it) argue for its existence.

There's a good reason why (to my knowledge) no one, including Hume (whom I've studied in great depth; I'm a member of the Hume Society), has advocated your view: you're giving a criterion for the existence of something. As a criterion, you have something very much like the verifiability criterion of meaning popularized by logical empiricists such as Carnap and Ayer and also by Popper. In other words, you're giving a way to argue that something exists; you're not stating that wherein the existence of something lies.

(It would be helpful for someone to write an article, Definition/Definitions versus criteria.

The empiricist David Hume was strong in his advocacy of the reliance on perception and experience as a door to the discernment of truth. But he did not leave it there. In An Enquiry Concerning Human Understanding he examined reasons to believe or disbelieve that existence is humanly definable and concluded: "The existence, therefore, of any being can only be proved by arguments from its cause or its effect" Even the destructability of a thing, he argued, tended to prove its prior existence. He held that the ultimate reason that people were able to argue for the existence of things based on their perception and experience was because of the relationship of Cause and Effect.

This is true, but it's not a definition of 'exists'. In fact, Hume argued that existence could not be defined; he famously challenged anyone to identify the unique idea whereby we get the idea of existence. He concluded that the idea of a thing and the idea of a thing existing were one and the same. (I disagree with him, I guess, but that's what he said.)

While we're beating our gums philosphically, I think this may be the one area where the force of Hume's logic served to defeat one of his basic holdings. Hume, I think, for all the thought he gave it, failed to reach an inevitable conclusion in his Cause/Effect examples. Cause/Effect implies at least one deeper, unifying quality or property and that could be called "interactibility." This may be indentifiable with the property of existence. Or not. Were a thing incapable of interaction, it could neither cause nor be affected. It might, on some theoretical plane, "exist" but be undetectable for the reason that means of perception require an effect to be created. So, for all physical purposes, its theoretical "existence" would be moot.

I don't believe Hume argued that existence could not be defined. I think he did hold that it was not a separable property. He said in Treatise of Human Nature that "the idea of existence must either be derived from a distinct impression, conjoined with every perception or object of our thought, or must be the very same with the idea of the perception or object". (his unique definition of "impression" required some real thing to impact the senses) He then went on to reason that since in his view there was nothing indicating the presence of any single impression that was "conjoined with every perception or object", there could be no unique impression from which the idea of existence could derive. He rather conceived there to be a function of identity (e=e). The thing and its existence were indistinguishable.

But the capability of interaction (ability to be cause or effect)is as much a quality (property, if you will) as location in space. It may in fact be more basic, since a thing must be interactible in order for relative location to have meaning, so one cannot locate it unless it is interactible. In fact, all properties flowing from the initial property of a thing's existence (its interactibility) can be described in terms of interaction. If you are not able to describe any current properties, it would be because there were no actual or currently potential interactions relating to the object, hence it would not be capable of interaction, hence it would for physical purposes not exist. So the current capability for interaction gives rise to any observed cause or effect, which enables location (the definition in the article) and any and all other properties.

This gives rise to an interesting circularity:

"in order for an object O to be detected to exist, it must be capable of interaction." "in order for an object O to be capable of interaction, it must exist."

If the latter statement is true, then interaction proves existence.

How about:

"in order for an object O to exist, it must be capable of interaction." "in order for an object O to be capable of interaction, it must exist."

Now let us bring in Karl Popper's falsifiability: Name an example of a thing which exists but which is incapable of interaction.

As for the example physical objects in the article: Name an example of a thing which exists but which has no location. Arguably, gravity. Not an object? Philosophically it is. Not physical? Definitely physical.

The terms of the two statements are mutual and could be said to be irreducible. e=e! The property which defines existence and existence itself are the same. The fact of existence is circular and therefore unprovable as a separate property, but not as a basic, necessary or fundamental property which enables all subsequent or secondary properties.

So I regard location as a secondary property. Hume's Cause and Effect statements led me to a different place than where they led him.

This has been a fun little excursion. For my part - the article may rest in peace.

Heh heh; existence = the property of having a property or properties. (chuckle...)

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