... is that they don't "get" reason. They don't know how to do it; they don't even realize why one should want to.* I generalize, of course, there are some exceptions. But for the most part, even intelligent non-philosophers** seem to lack the mental discipline required to follow a clear and logically rigorous argument. And that's a tragedy. It's something every kid should learn in school.
* = (Yes, I'm ranting, as you would expect from the post title. Yet here you are reading it anyway. Don't say I didn't warn you!)
** = (I should clarify that by "philosopher" I just mean anyone who has received sufficient philosophical training. They needn't be professional academics themselves.)
Spookyblog claims that "philosophers are getting pissed off" at the common misconceptions about our discipline, as pointed to in some of the recent "ten things" lists. I wouldn't say that, exactly. (Folk misconceptions about philosophy can be a source of much hilarity.) What really irritates me is the pathetic quality of public discourse on political and ethical questions. And, of course, the whole "not getting reason" thing mentioned above. But I think they're closely related. Anyway, here's a new list of common characteristics (of non-philosophers) that I find especially depressing:
1) They don't understand that rational argument is a form of inquiry. This leads many to close their minds to the perceived "threat" of another's persuasion. They think it's all just a matter of opinion anyway, and so don't bother to seek the truth by challenging their own preconceived beliefs. This leads them to "argue" insincerely. So the perception of empty rhetoric can be sadly accurate when applied to other layfolk and partisans. (And don't get me started on politicians!)
2) They seem incapable of focusing on a particular argument. They don't realize that the only way to make progress is one step at a time. They tend to want to tackle everything about an issue all at once. So half-way through an argument, they will suddenly demand that you address some completely different point. (Especially if the previous argument wasn't going well for them. Perhaps this is related to the intellectual dishonesty mentioned in #1 above.)
3) Perhaps related to the above two points: they only care about conclusions, and not the quality of particular arguments for getting there. It's only a slight exaggeration to say that they'd endorse the argument: "The moon is made of green cheese, therefore [insert any conclusion they agree with]." But rational argument is one arena in which the ends do not justify the means.
4) They constantly fail to understand how a point (e.g. an analogy or thought experiment) fits in to a particular argument, and instead insist on applying it more broadly -- and then objecting when this irrelevant application fails! It's so frustrating.
For example, it seemed like just about every right-winger who read my "stuck down a well" thought experiment failed to realize that its purpose was to establish the conceptual point that mere non-interference is insufficient for the kind of freedom that we value. (If you think the man stuck down the well lacks freedom, then you are forced to go beyond negative freedom, for he has no lack of that. QED.) Instead, they'd start complaining about how forcing people to help others out of wells would be impractical, yada yada yada. Completely missing the point.
Perhaps my exposition was insufficiently clear. But there is a trend here. Another example concerns G.A. Cohen's "ticket" thought-experiment, which illustrates how poverty is a form of (even negative) unfreedom. A commenter responded by "objecting" that Cohen's tickets and money were disanalogous in respect of origin -- something entirely irrelevant to Cohen's point about freedom. Again, very frustrating.
Focusing on the particular argument at hand is a really basic rational skill, and there's no reason why more people shouldn't be capable of this. It would make them so much more worth talking to. And that would be nice, don't you think?
5) Relatedly, they fail to grasp the import of hypotheticals. For example, it's easy to show that injustices could arise under pure capitalism (e.g. if all the propertied classes were racist and chose never to contract with black people, then the latter could never access any privately owned resources, and so would all starve to death. Few people would consider such indirect genocide "just"). This conclusively refutes the thesis that capitalism is intrinsically and necessarily just. It doesn't help to say that such situations would "never arise in practice". A theory of justice (or morality more generally) has universal scope, and purports to cover all possibilities. Any counterexample, no matter how outlandish or unrealistic, suffices to refute such a universal claim.
(Granted, one may legitimately raise concerns about the reliability of our moral intuitions in bizarre scenarios. See, e.g., here. I merely mean to criticize knee-jerk rejections of thought-experiments based on no further reason than that it "would never happen in practice".)
Perhaps more commonly, hypotheticals are also important for elucidating actual dispositions. For example, a fellow resident recently claimed to not care a bit about the suffering of distant strangers. I responded with my standard anti-egoist hypothetical: if you could save a million lives simply by pressing a button (which will also wipe all memory of your choice, so that it makes no difference to you), would you do it? He gave the politician's answer: "I don't do hypothetical questions." But of course he would press it - as I eventually got him to concede - and that proves that in fact he does value their lives to some extent (even if this could be easily outweighed by more egoistic concerns).
A third - and vitally important - use of hypotheticals is to clarify distinctions by separating variables that are commonly conflated in actual situations. Thought "experiments" allow us to control for confounding variables, and thus distinguish fundamental principles from others that they correlate with. (Consider Parfit's thought experiments for distinguishing prioritarianism from egalitarianism, for example.)
6) Logical fallacies. People who don't know logic reason poorly, and often can't tell when other people are reasoning poorly. The plague of illogic is totally unnecessary, and should be easy to remedy through basic education.
7) They hold silly views, like crude relativism, with a psychological certainty inversely proportional to the strength of reasons they can muster in its defence. (This may be related to #1 above. Most of the time, they don't even realize that any reasons are necessary. Such views are the "received wisdom" of popular culture, and hence need no defence. Right.)
Okay, that's enough ranting from me. Your turn... What annoyances have I missed? (Or if you like, turn it around and list "the problem(s) with philosophers"!)