Ok, this thing needs some serious rewriting. I have a clearer picture of what topics need covering, so I'll start putting an outline together now. This entry is VERY MUCH under construction, until such time as I remove this paragraph.

Existence and Process

Suppose I claim that the chair that I am sitting in exists. "This chair exists," I might say. What does this statement mean? Well, I have a more or less constant set of sensory experiences with which I identify this chair. I see it, and feel it, and sit in it. Others to whom I speak will aver that they too can see, feel and sit in it. Within my own mind and in my conversations with others, I use the noun 'chair' and am more or less understood. 'Could you please move that chair,' spoken while pointing in the direction in which I see the chair, produces the desired effect.

To summarize, I have a more or less constant set of experiences to which I refer when I speak of the chair in question. It is important to note that I refer to my experience of the chair, which is different from referring to the chair itself. The chair itself is difficult to pin down. Many philosophers have noted the difficulty of making claims about things in themselves. I agree with Hume that such claims are impossible to make with any degree of certainty. If some situation were contrived (brain in jar with stimuli fed in by computer, whatever) in which there is no chair, but there is a consciousness having a more or less constant set of experiences like those described above, then that consciousness would claim that the chair exists.

Now, we do not experience objects directly. I have no experience that I can call 'direct experience of a chair'. I can experience processes such as 'seeing a chair,' 'feeling a chair,' 'sitting in a chair,' 'agreeing with a vicar about the existence of a chair,' etc. Experience is always of processes, not entities. Note that there are two types of processes described here. Sensory Experience (seeing a chair) is a process that takes place within my consciousness. Consensus (agreeing withthe vicar) is a process that takes place between and among consciousnesses by means of language. When both types of processes occur more or less predictably, then we postulate the existence of an entity - a chair. This is a postulate of convenience, which is usually problem-free. With a couple of thought experiments, we can show that this postulate is grounded, not in some physical existence of the chair, but in my experience of certain processes.

Thought Experiment #1

Imagine I remove one leg of the chair and replace it with a new one. I can do this to each leg in succession. Next the cushioned seat is removed and replaced by a new one, then the back, the arms, and so on for every part of the chair. Is it the same chair? It has no physical parts in common with the original chair, yet my experience of it has been more or less constant. It is 'the chair I've been working on'.

Thought Experiment #2

Now suppose I get tired of the chair and decide to destroy it. I take it out into the desert, cover it with gasoline and set it on fire. By the time it is consumed, most would say that the chair doesn't exist anymore. All the matter out of which is was made still exists, it is just organized differently, as smoke, ash and miscellaneous metal parts. There are points early in the burning at which I could put the fire out and say that the chair still exists. Somewhere, however, a line is crossed beyond which no act of mine can salvage the existence of that chair. Beyond this point, all sensory processes to which I used to refer when I spoke of the chair have ceased. Light is no longer reflected in a such a way that I can 'see the chair.' The molecular bonds which used to maintain tension when I could 'feel the chair' are no longer bonded.

Hopefully these thought experiments have shown that the existence of the chair can be entirely referred back to the occurrence of certain processes. We saw earlier that there are two types of processes which convince us of the 'existence of entities': Sensory Experience and Consensus. The latter trumps the former. For example, I can hallucinate a chair, but if everyone else assures me that there is no chair, although I see it, I will agree that the chair does not exist. Also, Consensus can establish the existence of entities of which we have no sensory experience. I believe that the Great Wall of China exists, although I have no sensory experience of it, and people can agree upon the existence of love, grammar, or differential equations, though we have no sensory experience of these things. There are processes that occur within the consciousnesses of humans, about which we have some degree of consensus, which underlie the existence of these abstract entities.

It is usually not necessary to use a process description to talk about 'entities'. For most everyday business, an entity description is perfectly servicable. When we are attempting to be precise about existence, as in Physics, it can be productive to revert to a process description to avoid nonsense. ('Electrons are both particles and waves.') A process description of an electron is what Physicists must be content with.