Existence is a concept that is at the centre of philosophy and on which the definition of 'truth' and 'falsehood' tend to be based. Nowhere have I found a satisfactory definition of it, and I have an intuitive felling that it may be undefinable. Please contribute your definitions, and we'll discuss whether they work and what the ramifications of that definition are.

Existence is the knowledge that the point of reference located within your awareness is the center of the universe.  Everything revolves around you.  It makes no difference to know the location of the planets, the sun, where you are in the universe.  You just know that everything revolves around you.
Now, how can this be?  How can everyone be the center of the universe?
Easy, just use the metaphor of the holagrammic picture.  Every perspective is the center of the image.  That is just the way it is.  Logic does not play a part in this determination.  That is the hard part to understand.  Logic is a microscope examining the parts.  Intuitive thinking is the way to view wholeness.
Decartes said "I think therefore I am".  He was only partially right.  Substitute "feel" or "Intuit" or "Sense with my five senses" in place of "think" and you will be equally right.  Perhaps more inclusive would be to say:
"I am aware of my existence, therefore I am"

Existance is and it isn't.
I am that.
Or as in the Brahma sutras "Neti Neti"
Not that, not that.

to say this/that exists is to objectify perception, a fundamental operation of objective analysis.

to say I exist is redundant


8)

baaahahaha preacher joe. Gross!  ;D

Your right I think with your feeling of it being undefineable seanf. In the same moment I think about why the hell I or anything else even exists I just gave the black nothing of reality and death a context to base itself on. Unbelievable isn't it? Conceptual context. My very desire to uncreate all this in front of me and make it disapear has given it the power to crystalize itself and be me "thinking about it all disapearing". Its a prison for your mind! Its a natural unfolding. The very notion that there is total nothingness just MAKES the somethingness appear out of nowhere into all it can be. And here I am typing and cannot escape! Yaaarrg! :-X    

O.K, interesting answers.
Synchronox, I understand what you're saying, but I don't think you've actually defined it, just stated something about the nature of existence for a conscious being.

Joe, I just didn't understand your post.

Shindak, it is possible to try and define it. For example, "to exist is to have an effect on experience." I know this is too limited, but it's the best I've got at the moment, so lets see if we can build on from there.

QUOTE

." I know this is too limited, but it's the best I've got at the moment, so lets see if we can build on from there.

This is an excellent stage of progress.

seanf,

"Defined it"?  Are you using this in an objective framework?
Existence implies perception, does it not?  If it is perception, "I think, therefore I am" it is subjective and therefore not amenable to objectification.
My explanation is adequate for the demands of subjective understanding.  I do not think subjective information can be stated in an objective fashion without a great deal of distortion.
The difficulty is our way of expressing things is left to examination by a calculative manipulation of dead things-modern science.  I don't believe science is misplaced in this endeavor, only misused in fields it should not be present.

some philosophies think existence is just a grammatical concept without meaning.  you can say, something came into existence, but it doesn't mean that this something enters a certain realm, only a certain state.  but this state is redundant with everything existing, and can't be abstracted from it.
meaning, you can't talk about existence per se, you can only talk about the things that are existing.  i think the same criticism has been applied on the concept of 'being', or 'Sein' in german.  doesn't exist either, only the 'Seiende' exists, but in english it's the same word.
so, instead of talking about existence you can talk about the world, then some misunderstandings will be avoided.

The problem comes when you try to have a logical argument about something. It will be based on 'truth' and 'falsehood.' Bertrand Russell helpfully defines a 'true belief' as when the complex object of the belief exists. However, you then come up against the meaning of 'exists.'

We can't know what existance is in periods of our "non-existance" - like every time we dress up our bodies....We'll have plenty of time to figure it all out in times of EXISTANCE.
We just need kilometers of "experience"..    
Hey,I'm new here...so I donno exactly how this work...Hope you don't mind me..    
                               


                                                 Kundalini    

Hey Kundalini, welcome to the board. I've been here for a few months, and I think this is actually my first post ever.  I wouldn't have even posted except that your post ( "We can't know what existance is in periods of our 'non-existance' - like every time we dress up our bodies....We'll have plenty of time to figure it all out in times of EXISTANCE.
We just need kilometers of 'experience'.. ") makes absolutely no sense to me whatsoever. Care to explain what you mean?  Thanks.

Rooftop

An excellent challenge, this! Whilst synchronox's reworking of Descartes' line is interesting, it implies a requirement for consciousness. So perhaps more fundamentally, can a non-conscious (or non-living) entity be said to 'exist'? A stone, or an electron? Certainly in seanf's definition of 'having an effect on experience' - a stone may trip up a man. So here's my stab at the definition - all 'things' that we are and sense (or, as Poe would have, "all that we see or seem") are simply aspects of an underlying, ever-changing unity, therefore existence is to be an aspect of this, what David Bohm terms "the implicate order". Perhaps this just shifts the responsibility up a level, without really providing a definition, but maybe this is the nature of the problem.

Existence - what a lovely terrain to explore. Always treading softly but masquerading boldly at the same time. Existence exists out of the necessity of the alternative. Which is nothing. Most people understand nothing as a black void - but that is something. In order to understand "nothing" you need no consciousness. Like a rock,  unaware of our "existence". We see the rock, does it exist? According to our peception, it does. Existence is consciousness. That´s all. Without consiousness there is "nothing" and without consciousness - there is nothing.

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Existence is consciousness. That's all. Without consciousness there is "nothing" and without consciousness - there is nothing.

Unfortunately, that claim is unfalsifiable since our being, our existence, seems to necessarily consist of consciousness.   Hence, if there is a form of being that does not consist of consciousness, we will never experience it.     But can we infer such things?  perhaps.  Consider the mathematical structure of the universe;  wouldn't you agree that this mathematical structure has being, has existence, separate from consciousness?    Or would you assign the universe's mathematical structure to the realm of consciousness?  It seems to me that such mathematical structure must exist implicitly before we become conscious of such structure, and as such, mathematical structure possesses an existence separate from individual consciousness.    However, if you adopt some form of panpsychism, which says that 'everything is consciousness', then that would assign mathematical structure to the realm of consciousness.   But, if we assign everything to the realm of consciousness, then how do we know that 'consciousness', as we understand the term through our own experience, is identical to the 'realm of consciousness' that is hypothesized to contain everything?

It's limited to say existence is only consciousness. All we, as conscious beings, can ever directly know is consciousness. It doesn't follow that things can't exist without consciousness, just that we can't directly experience other forms of existence. There is Shawn's point about maths, and more dubious ones about spacial relationships and even ethics. There is also the idea of the thing-in-itself, as seperate from consciousness. There may be many other types that we cannot even infer.