If you say P, you assume that it is clear that P is not, not-P.

Here's a common kind of discussion that you might have with a Gangadeanian (G). I've had discussions of this sort on more than one occasion and I think it's a common approach that Anderson also likes to employ. Hence, I hope it will be instructive to my readers. 

G: Do you deny that some things are clear? 

Me: I don't think we can be absolutely certain about much of anything if that's what you mean by clear. But I don't really know what you mean by clear, so can you explain the term? 

G: So is it clear that you don't know what I mean by clear? 

Me: I don't really get what you mean by clear. Could you elaborate.

G: In your statement just now, you said, 'you' so is it clear that there is a difference between 'you' and 'not-you'? Is there a difference between "I" and "not-I", "don't and "not-don't" "really" and "not-really" "get" and not-get...."  

Me: I still don't understand what you mean precisely by clear. Can you define it for me? Well since you are saying there is a clear distinction between each of those words and what you take to be their opposites, shouldn't you be able to define them for me?  

G: Is there a clear distinction between "define" and "not-define" and "me" and "not-me." See, you are lacking integrity if you claim that nothing is clear. You are assuming that some things are clear in even arguing with me. 

What is frustrating about this exchange is that my interlocutor thinks s/he has shown something. But I have no idea what that is. They shut me up for sure, but not because they offered anything like an argument or demonstration that was undeniable. I was shut up because I was confused. So let's try to get clearer on what the intent of the approach is and then I'll say why I think it's ultimately mistaken.

The intent: The point seems to be to show that everyone, always, everywhere that thinks or makes intelligible assertions assumes clarity at a basic level (note it's 'clarity' as they define it and 'basic' as they define it and also 'assumes' too). Notice that my interlocutor never defined the pertinent term 'clear' or 'clarity' for me. They just sort of went forward in showing me what denying it amounts to (which should raise eyebrows given how they also believe that meaning is more basic than truth). My guess is s/he doesn't have a very precise definition and so none was given. But let's start with a rough sketch: since clarity is linked up to inexcusability and both Gangadean and Anderson speak of clarity in terms of being absolutely sure of some proposition (in some cases a proposition about a distinction of concepts?), I guess the idea is that something is clear just in case you couldn't possibly be wrong about it insofar as you believe it. There are going to be lot's of issues in getting precise about this, but let's just run with it because I suspect the Gangadeanians have something like this in mind (i.e., I'm setting aside issues of whether it's a good account of the concept/word to begin with).

The second misstep in my interlocutor's approach is that they conflated two different positions. I didn't deny that some things are clear in any dogmatic sense. That would be not only self-refuting, but I just don't feel that strongly that clarity is not possible. I'm just on the fence about it. In other words, I'm not certain about clarity at the basic level and I want to be convinced of it before I accept it. I mean, Gangadean insists that some basic things are clear, and I just want him to support this claim in a way that is consistent with his other pronouncements. Anyway, the point is, my interlocutor mistakenly took my not affirming clarity for my denying clarity. But the two are not equivalent. I certainly have doubts that clarity of the sort that Gangadean is after and suspect that it is unlikely, but that doesn't amount to being sure that there is no clarity. (e.g., one could not be sure that God exists or even have doubts about whether God exists without being certain that God does not exist).

Now if I'm not actually dogmatically denying clarity, but am rather not sure or doubt whether things are as clear as Gangadean and his people think, then I'm not really sure what my interlocutor has accomplished by her/his line of questions. Maybe it's something like, "let's imagine that there is no clarity since you're on the fence and I'll show you how it leads to inconsistency." But I'm not sure that the line of questioning even succeeded at that. Note that there is no actual argument presented. A line of questioning does not count as an argument with valid inferences and true premises. Nor does it count as a proof by contradiction, since again we need premises (which are assertoric statements not questions) and a conclusion. Still, there's a sort of informal dialogue going on which is meant to show or represent some inconsistency, informally.

Again the main aim is to show that by making any assertion, or asking a question, or thinking or whatever, I am assuming clarity at the basic level. So if I were to deny clarity at the basic level, then I've just been inconsistent because in order to deny it, I have to assume it. So what needs to happen is that the Gangadeanian must show that I am in fact assuming clarity at the basic level anytime I think, or assert or argue or whatever. 

But I don't see how the line of questioning that my interlocutor participated in makes good on that end. I mean how do you even begin to show someone what they are assuming whenever they think or talk? Sure that's what you think is going on, because it's part of your worldview already, but you haven't shown anyone that happens not to share your belief that your take on the matter is true.

So really, what I think is happening is that my interlocutor already has in mind something like, "in order to make intelligible assertions, questions, or the like you must presuppose clarity or epistemic certainty at the basic level."  Remember this is what we just concluded that s/he must show is true. I think that it just seems or feels or appears to be trivial or obvious to them.

But have they actually given you any reason to agree with the claim that in making intelligible assertions, or raising questions, or in order to think or doubt or know anything, we have to accept or presuppose absolute certainty or clarity of some basic things? Has the Gangadeanian done anything to actually support this claim? I think it's a rather non-trivial claim about the very nature of thinking and asserting intelligibly, and so I think they need to explain how they know it or why one ought to accept it. I mean, why do I have to be absolutely certain of basic distinctions, in order to make intelligible declarations? discussions? arguments? have intelligible thoughts? Again what justifies this claim? Can't I just be somewhat sure of basic distinctions and make meaningful statements and have meaningful thoughts? I just don't understand where they get these norms of thinking, assertion and the like. At the very least they need to support their claims. The line of questioning that we enumerated above then is somehow supposed to show you that this assumption is true. But what I want to point out is that it fails to do that, or at least it isn't obvious how it achieves it. In fact, I don't think it's the sort of thing that can be shown by way of any argument. It's likely something you just have to immediately grasp, or intuit. The problem is, for some it's quite obvious and for others it is not. So the Gangadeanian hasn't made any actual progress as I see it.

Now the Gangadeanian is likely to respond to this challenge in this manner:

"Look, in order for you to say all the things you just said, aren't you assuming clarity of basic distinctions?" In other words, they are likely to respond with just another iteration of the same line of questioning. They might say, "see, you're using all these words and concepts in disagreeing about my approach, which means you're assuming basic distinctions!" And again whatever you say in response, will be met with, "is there a distinction between, whatever words you used and their negation?"

But this is just a reiteration of the same reasoning which depends on this background assumption that they haven't actually shown you is true. So in response to your worry, they have in effect just repeated what they said before. I think this is nothing more than a flat-footed response to your inquiry. It's table pounding or maybe it's intuition pumping with the illusion of real movement. But it doesn't show anything. Perhaps your response should be equally flat-footed. When they ask you whether you assume certainty about basic distinctions (or clarity) whenever you think or make assertions, perhaps the best response is, that it isn't obvious that you do. If they introduce epicycles of the same question, you will always be able to respond in the same way---ad infinitum.