Clarity. The quality or state of being clear. Lucidity. The quality of being easily understood. From the Latin clarus; claritas.
This quality or state is generally considered desirable, and not just in communication. It's believed fortunate for some of us to experience a moment of clarity or lucid interval. In medicine, a lucid interval may be considered a period of time in which the patient is suddenly alert and responsive; in the law, someone demented may during a lucid interval have the capacity to sign documents such as a Will which are accorded legality despite the fact that they are often non compos mentis.
That's all it takes, really; one doesn't have to be knowledgeable or aware at all times. It suffices to know what you're doing while doing the act which is significant in the law. This is why it can be most difficult to establish someone was incompetent at the time a Will or other document is executed. Someone must testify to that incapacity obtaining at that time. Few are willing or even able to do that except where the incapacity is apparent and is observed at the time of execution of the document.
Surprisingly, (to me at least) it seems to be the case that clarity in language is not accepted as preferable, or worthy, or good in all cases, and that this is true in particular in the case of certain circles in philosophy. Perhaps I should say that this is alleged to be true. It is claimed, even, that certain philosophers practice obscurantism; i.e. they are deliberately ambiguous, they try to be incomprehensible.
I find this hard to believe. I can't understand why a philosopher would want to incomprehensible. The charge of obscurantism seems to come from those philosophers of the analytical tradition and is applied to those of the continental tradition, and this itself renders it suspect as far as I'm concerned. Analytic philosophers are inclined to consider continental philosophy obscure by nature, I suppose. But why would anyone want to be obscure?
It's difficult for me to imagine being against the clear, the lucid. It strikes me as similar to worshipping a god who delights in or is intent on destroying the wisdom of the wise. It makes no sense, unless there is a particular purpose in mind, and such a purpose would seem to me to be necessarily contrary to reason. But proponents of the irrational would see this as desirable, no doubt.
There's no denying that I find it very difficult to read continental philosophers. I don't find them hard to read as I find Dewey hard to read. I find Dewey hard to read because he writes badly. It's difficult to read his work as a result, but I'm reasonably certain I know what he's saying (or trying to say) in most cases. I don't think I know what continental philosophers are saying, or trying to say. The words they use are often unfamiliar to me, as they are used, and they seem excessively inclined to metaphor. This isn't necessarily to say they write badly, though. Rather, they substitute metaphor for explication.
There's a danger is this method, though. Metaphor may be essential in evoking certain thoughts and feelings, but to use language as needed to achieve evocation of this kind is a rare talent. One sees it only in great poets, in my experience. Philosophers are dreadful poets. When they try to be poets or artists, I don't think they create great philosophy. They create bad art.
It's quite possible to write obscurely without intending to do so. To claim that philosophers deliberately try to be obscure seems to me the equivalent of claiming that they commit a fraud, and a claim of that kind shouldn't be made without evidence.
Obscurantism would be something engaged in by those who wish to limit or restrict knowledge to a certain group, already possessing that knowledge. When knowledge is intended to be hidden from others, it may take on occult characteristics. The knowledge becomes secret, a kind of gnosis open only to a few, the initiated. Certain words or phrases are used which have meaning only to the initiates.
A difficulty arises, though, when complaints that writing is unclear are met by claims that it is unclear only to those unable or unwilling to comprehend, or that the meaning is so sophisticated that it cannot be expressed in everyday, ordinary language. That kind of response implies that the meaning is open only to those capable of transcending language; those who no longer need to have meaning explained to them.
From that point on, it becomes an open question whether obscurantism is at work. Clarity simply is not something one would want to dispense with or avoid if there is a desire to communicate thoughts and ideas. When it is dispensed with it must be presumed that it cannot be obtained, which suggests that there is nothing worthwhile to be communicated, or that it is undesirable, which suggests much the same.