Clarification/Follow-up by tonyrey on 05/13/08 9:32 am:
Jim, we certainly don't need absolute certainty in order to act but once we start doubting whether we are thinking we find ourselves in quicksand. To doubt constantly whether we exist, or indeed whether anything exists, is akin to insanity. It is such a fundamental truth that every other question pales into insignificance until it is resolved. To take existence for granted is unscientific to say the least. Is it possible one day we shall discover we are not thinking? Clearly not because we have to think in order to know or discover anything. How then can it not be an unassailable truth?

There is a radical difference between investigating the possibility that all truths are questionable and adopting it without further ado as a self-evident truth. To maintain it is not something you have to justify amounts to regarding it as a truth that will never be disproved or falsified.And what is that but an absolute truth?

Since logical and mathematical truths are known with absolute certainty there seems little point in denying there are other truths in that category.

Clarification/Follow-up by Jim.McGinness on 05/13/08 12:19 pm:
It has been my experience that every time someone thinks they have an absolute truth, someone comes along with a valid skeptical argument about its truthiness. Perhaps your experience is different?

Mathematics did not fall entirely apart when Godel published his incompleteness theorem. The research programme for combining logic and mathematics into one absolutist-based grand architecture failed, but mathematics remained.

Clarification/Follow-up by tonyrey on 05/13/08 2:40 pm:
Jim, I haven't come across anyone, philosopher or not, who has argued that nothing exists...

Clarification/Follow-up by Jim.McGinness on 05/13/08 10:57 pm:
Tony,

Surely you've run into opposing philosophical views that claim, on one hand, that only material things truly exist, and the other hand that says, material existence is an illusion and only ideas or consciousness truly exist. In some formalistic way, you can take these two opposing views as agreeing that something exists, but taken together they raise the question of whether anything exists.

I believe you have representatives of these two views on this very forum.

Clarification/Follow-up by tonyrey on 05/14/08 3:04 am:
Jim,

How do you obtain "neither A nor B" from "either A or B"?

The divergence of views about reality does not imply there is no reality.

As Lear said, "Nothing shall come of nothing". How could thought be dispensed with? To assert that nothing exists is a self-contradiction because the assertion "nothing exists" exists!

Clarification/Follow-up by Jim.McGinness on 05/14/08 6:31 pm:
Tony,

I don't know much Wittgenstein, but aren't we now playing word games with the meaning of the term "exists"? If we both agree that "something exists" but cannot find any one thing that both of us agree exists, we remain at a sort of impasse. If thought and concepts are considered epiphenomena of the activities of material brains and, in and of themselves, don't have an independent existence, I can certainly hold the view that the assertion "nothing exists" is not necessarily a self-contradiction.

I'm not supporting a position of nihilism or total skepticism. But those are not the only alternatives to your claims of absolute or "unassailable" truths.

Clarification/Follow-up by tonyrey on 05/15/08 2:14 am:
Jim,

By rejecting nihilism you confirm that it is impossible to deny anything exists without being inconsistent. Even epiphenomenalists accept the reality of physical brains.

If you hold the view that nothing exists you are denying that you exist. And if there is no one to make assertions then the assertions cannot exist!

We may reject all existing interpretations of thought as false but mental activity is implied in "reject" and "holding a view". Reality, whatever it may be turn out to be, is a fundamental and inescapable fact.

Clarification/Follow-up by Jim.McGinness on 05/15/08 6:23 am:
Tony, you are as self-contradictory as you claim I am: a reality which you cannot characterize with much precision, which you can't truly know, is not the sort of "fundamental and inescapable fact" you can base your philosophy on. If we agree to treat our knowledge of reality as tentative and provisional, subject to revision if additional evidence comes into consideration, we'll be in a better place to begin discussions.

Clarification/Follow-up by tonyrey on 05/15/08 4:11 pm:
Jim,

The assumption that all knowledge is provisional implies that our knowledge that we are thinking is subject to revision. If it is discarded how would we be in a better place to begin discussions?

Clarification/Follow-up by Jim.McGinness on 05/16/08 4:50 pm:
Tony,

It would then be possible to ask exactly who or what is doing the thinking, whether there are unconscious processes into which we have little introspection that have a lot to do with the process of thinking, what kinds of activities do we include in the category "thinking", how "thinking" differs from perception, etc.

Clarification/Follow-up by tonyrey on 05/16/08 7:13 pm:
Jim,

The questions you pose are certainly relevant but my point is that it is unreasonable to deny the existence of thought because to do so presupposes thought. That is why I regard it as a fundamental fact even though we do not understand it completely.

Clarification/Follow-up by Jim.McGinness on 05/16/08 9:58 pm:
Tony,

I guess my remaining objection is to the use of the word "fundamental" when the knowledge is incomplete or incompletely understood. When you use the word "fundamental" or "unassailable", I take you to mean that the fact in question is fixed and completely understood; that there can be no further argument about its interpretation. I see you as wishing to use these fixed and immutable facts as if they were axioms from which it should be possible to build a comprehensive philosophy or a complete description of reality.

In one interpretation, the presupposition of thought in the proposition that "thought exists" is a mere tautology of definition. You might be able to use it as a starting point to build something, but what you build will most likely falter as you deal with the precise sense in which "exist" is used. Sliding in other meanings of the word "exist" may or may not work, depending on how diligent you are to qualify each new usage.

Clarification/Follow-up by tonyrey on 05/17/08 3:09 am:
Jim,

I do not believe any form of human knowledge is complete or completely understood, given that our intelligence is limited. The term "fundamental" is unfortunately associated with fundamentalism and has given you the impression that it entails "a comprehensive philosophy or a complete description of reality". Nothing could be further from the truth.

The reality of thought is a modest starting point but I regard it as a primary and inescapable fact because it refutes total scepticism (which is the question under consideration). The success of science demonstrates that the physical universe is intelligible - to a certain extent. And intelligibility implies thought...

Clarification/Follow-up by Jim.McGinness on 05/17/08 2:11 pm:
Tony,

You lost me with that last one.

Time for a new question?

Clarification/Follow-up by tonyrey on 05/17/08 5:08 pm:
Jim,

How about the intelligibility of the universe?!