I also believe that there are many things that we would agree on; my arguments are just an indication that I currently find certain aspects of this topic interesting to argue about--mind expanding. :)
I want to make the case, though, that experience itself is neither "certain to exist", nor "uncertain to exist". I think that "experience itself" is fundamental to Dasein, and that therefore cannot be subject to either certainty nor uncertainty.
I am happy to hold my arguments against certainty for shiftedShapes--however I will now make similar arguments against your claim that '"experience itself" is fundamental to dasein'.
The identification of a fundamental nature of Dasein requires a perspective and so is contingent on that perspective, and presumably on the limited access that perspective has to the thing it identifies as Dasein.
I will offer a competing view. Dasein is only fundamentally 'blue hat'. It feels obviously 'blue hat' to me; without 'blue hat' it would not be Dasein; nothing else about it is essential.
Presumably neither of our claims change the actual nature of what we are attempting to refer to when we say Dasein. Dasein and our conceptions of it are concepts generated by and within... well, by and within our Dasein in some limited sense.
The problem with both of our claims is then sense in which we are attempting to establish a description as a matter-of-fact. We are implying a universal perspective from which our claims can be understood to be true. Such a perspective seems inaccessible to me, so I will treat this kind of attribution as an error, perhaps as a 'not even wrong'.
So I agree that experience itself is neither "certain to exist", nor "uncertain to exist", but in the same mode I would add that "experience itself" (or "blue hat") is neither "fundamental to Dasein" nor "non-fundamental to Dasein". At least I would make this assessment when there appears to be an implied universal perspective involved.
If "experience itself" really is a fundamental element of dasein, then, we can think of it as an axiom of the human condition. Since we can only observe from within the human condition, this places the question of the existence of experience beyond proof or disproof, beyond contingency, and therefore beyond certainty or uncertainty.
If you were to say that there is a perspective from within the human condition, from which "experience itself" appears to be a fundamental element of Dasein. I would not argue, it is an ontology we can work with as long as it seems useful. If you were say that this perspective was primary, complete, unquestionable, fundamental, or certain then I am currently tempted to question the basis of your claim, the perspective from which your claim is made, or from which it holds.
Ah, here is where our opinions diverge sharply. I should mention quickly that I have edited my above post slightly - I had accidentally left out a few words at the beginning of the first paragraph. I don't think it changes the thrust of my argument at all.
I have to tell you, I think you're misapplying this whole "problem of perspective" thing. I agree that it exists, but I don't think it's as far reaching as you're implying: if it were, it would be impossible for anyone to understand anything ever. We are able to understand some things, so,...
Stanford Encyclopedia : Perception
Wikipedia : Direct and Indirect Realism
On various philosophy forums I've participated on, there have been arguments between those who call themselves 'direct realists' and those who call themselves 'indirect realists'. The question is apparently about perception. Do we experience reality directly, or do we experience it indirectly?
When I was first initiated to the conversation, I immediately took the indirect side -- There is a ball, photons bounce off the ball, the frequency of those photons is changed by some properties of the ball, the photons hit my retina activating light-sensitive cells, those cells send signals to my brain communicating that they were activated, the signals make it to the visual cortex and...you know...some stuff happens, and I experience the sight of a ball.
So, my first thought in the conversation about Indirect vs Direct realism was that there was a lot of stuff in between the ball and my experience of it, so, it must be indirect.
But then I found that direct realists don't actually disagree about any part of that sequence of events I described above. For them as well, at least the few that have bothered to respond, photons bounce off a ball, interact with our retinas, send signals to the brain, etc. The physical process is apparently the same for both sides of the debate.
And when two sides vehemently disagree on something, and then when the question is broken down into easy, answerable questions you find that they actually agree on every relevant question, that tends to be a pretty good hint that it's a wrong question.
So, is this a wrong question? Is this just a debate about definitions? Is it a semantic argument, or is there a meaningful difference between Direct and Indirect Realism? In the paraphrased words of Eliezer, "Is there any way-the-world-could-be—any state of affairs—that corresponds to Direct Realism being true, or Indirect Realism being true?"