Is coherence subjective

Question

When an argument is dismissed by an individual for being incoherent, is there an objective standard to which coherence can be held?

I'm trying to determine the difference between the statement "that argument is incoherent" and "that argument makes no sense (to me)."

Answer 1

Well, "incoherent" isn't set terminology. I'll go over which concepts are used to evaluate arguments and how they might relate to arguments being called "incoherent".

If we want to formally reject an argument, we'll reconstruct it into propositional logic and examine for validity and soundness. Such an argument might look like this:

P1) If it rains then the street is wet.
P2) It rains.
C) The street is wet.

An argument is valid iff it's impossible for the the conclusion to be false if the premises are true. The argument above is valid because if both premises are true then the conclusions must strictly follow. We're looking only at the logical structure. If an argument is invalid then we have to change it or reject it.

An argument is sound if it's valid and the premises are also true. So, this step requires evaluating the premises. In the above example we need context. Is the street maybe under something, so P1 is wrong? Are we going to reject P1 because wetness is imprecise? Does it in fact rain, so is P2 true? If an argument is unsound then we'll have to change or reject it.

In philosophical arguments this will of course require lots of discussion. But if an argument is clearly invalid or has factually wrong premises then we might say something like: the argument is incoherent. (If we want to be careful with the word "objective" then we could at least say that there are intersubjective and/or universal standards. For soundness that can be the case but doesn't have to be.)

By "incoherent" we could also mean that it's not understandable. Which is the case if terms are unclear etc. Or if we just can't reconstruct it in order to evaluate validity and soundness. Some arguments are just too extensive to easily reconstruct. Often arguments will also be enthymemes, arguments in which some premises are not explicitly stated. For this there aren't any clear standards. Something could clearly be not understandable without further explanation. Or it might just be a subjective evaluation. Theoretically we could formally evaluate whether something is understandable with text linguistics if we want to be completely transparent about which standards we use.

Answer 2

I teach my students that arguments should be clear -- which I clarify as concise, concrete, consistent, having a sensible order (conclusion at the front or back), and free from loaded language.

Baying "this argument makes no sense to me" and "this argument is incoherent" are both critiques of the clarity of an argument. Sometimes theses critiques are unjust because the reader/listener is unjust, but assuming the critique is right, then I'd formalize it as one of the following:

1. There are inadequate connectives between the premise and conclusion (the operations used don't logically connect to the conclusion)
2. There are excess or absent premises. (unneeded premises are there or needed premises are absent).
3. There are consistency problems in the use of terms, i.e. two different words are used for the same meaning, etc.

I think these are pretty objective things that differentiate a coherent "this argument is inconsistent" from a thoroughly subjective "this argument makes no sense to me!" (the point here isn't the wording of course but what the person means with respect to the argument).