Write clearly. And respectfully.
Philosophy starts with simple questions. We build a path toward an answer one logical step at a time. The goal of writing about philosophy is to clearly share the questions and the path we build toward answers.
Historically, many philosophical writings which are difficult to understand have been hailed as works of genius. Enough are both difficult and revered that it becomes natural to assume difficulty is a good thing.
We think we cannot easily understand people who are smarter than us. When we have trouble understanding an essay, it is tempting to think that the writer is very intelligent. A better response is to realize that the author is not writing well, and to treat the value of the ideas as independent from the quality of writing.
To write well about philosophy, express ideas clearly and simply, as if talking to a friend. After all, this is essentially what you're doing.
Philosophy is full of new ideas. It's natural to want to invent new terminology for new ideas. A self-descriptive phrase consisting of known words is useful. Entirely new words or meanings are less useful. It is not up to any one person to decide how to change the building blocks of a common language. An author's domain is thought, and capturing those thoughts clearly with well-known language is victory.
In Being and Time, Martin Heidegger speaks at length about Dasein – or there-being as a rough English translation. His definition of the term is hard to express succinctly. A helpful excerpt from Being and Time is: "This entity which each of us is himself… we shall denote by the term Dasein." Those new to the idea may feel pressured to read an entire book to grasp it. I admit I'm not an expert on Dasein, so that I can't suggest an accurate phrase to replace it. However, for the sake of discussion about language, what if Heidegger had instead used the phrase intrinsic existence, as a variation on the traditional concept of existence? Readers may find it easier to grasp and play with such a phrase that does not alter basic definitions, that is recognizable as a distinct concept, that brings us close to the author's meaning before further explanation, and that hints there is still room for an author's particular perspective.
The words email and tweet, as in a twitter-based tweet, have been added to common language over time. In each case, the concept has been known to much of the English-speaking population, and has proven to be interesting for several years before its name became official. Email evolved naturally from e-mail, and electronic mail before that. There was not a decisive moment when everyone agreed to collectively switch from one to the next. In practice, new words are formed by unsupervised popularity – and this popularity is often guided by usefulness. It is not usefulness to the author, but usefulness to people discussing the concept.
In the end, language does evolve, and new words do appear – but only after a concept has been around long enough to evolve into a common vocabulary.
It's distracting to fixate on words. Consider this argument: Lettuce is better than nothing. Nothing is better than pizza. Therefore lettuce is better than pizza. The conclusion is almost offensively false. It is easy to accept each individual sentence as true, and the surface-level logical structure as true. Of course, there is a disparity in the meanings of "x is better than nothing" and "nothing is better than x." They do not match the naive mathematical analog of x > 0 compared to 0 > x. The point is that we must keep in mind the ideas represented, and not lose the thought-forest for the word-trees.
Whilst grandiloquent rhetoric affords an air of adroit ratiocination, its employment is no guarantee of effectuating comprehension of the hypotheses in question. In other words: big words sound smart, but don't clarify your ideas. The point is to be clear.
There are other habits that are shortcuts for authors and longcuts for readers. In particular, -ism and -ist words point toward a school of thought. For example, we could ask if fatalism presumes determinism. Or we could ask if you can think everything is inevitable even in the presence of free will. Avoiding isms may be lengthier, but it is more direct.
Avoid assuming the reader is familiar with any given philosopher or argument.
What you write will be easier to understand if it assumes no particular previous literature has been read. If there are only a handful of ideas to use from another work, they can be summarized. You may have different interpretations of the literature than your reader. Stating old ideas in your own words makes sure the reader is aware of your perspective.
If there is no point in someone reading what you write without understanding a previous work, you may explicitly say so, and write as if they've read it. It is polite to review the basics of the previous work, even in this case.
Write only in the language of the reader. It sounds intelligent, and better preserves the original meaning, to quote great ideas in their original language. For readers who do not understand the language, however, the meaning is utterly lost, and the flow of the writing has been shattered.
An argument is easier to follow if it flows nicely from a question to an answer. It is tempting to interrupt the flow to elaborate a point. Often such an elaboration takes away more than it adds.
Avoid parentheses (like these). Parentheses are psychologically harder than commas, so that a separated phrase feels more like a speed bump. When there's a choice to use commas, like this, use them instead.
Better still is to write with minimal pauses. Periods and paragraphs are enough to let the reader catch their mental breath.
If parentheses are speed bumps to a reader's journey, then footnotes are canyons that split the road. At very least, a footnote-ignoring reader must skip a superfluous note and try not to feel guilty about it. A respectably careful reader will stop mid-sentence to travel a page away for a tangent stream of ideas. Their mind and eyes have been jostled. When they return, they have lost their flow.
If a footnote doesn't give credit to another work, then it can be modified to fit directly into the text in a natural way – or left out altogether. If credit must be given, it can be given within the text. If editorial style allows it, the author can cleanly separate references from the text, so that nothing but a focused flow of thought lives on the pages the of the main text. If the editorial style is strict, the author may still refuse to use footnotes or references except as citations at the end of sentences. In that case, if it is obvious that these are citations rather than notes with text, the reader's flow can be better preserved.
Avoid extra quotation marks. Like parentheses, quotation marks have a visual heft that hinders flow. In some uses, the meaning of the marks are not clear. The common interpretation of quotation marks is to separate the remarks of the author from statements about words. Not all uses are black and white.
In chapter 5 of John Searle's The Mystery of Consciousness, he says,
[a machine] does not have any inner feelings at all, because there are no such things as "inner feelings."
Is it necessary for the second inner feelings to be in quotes? A pedantic writer might argue that the meaning changes subtly if we drop the quotes, but I'd say that any reader can grasp the meaning either way.
When in doubt about quotation marks, try italics instead. If that works, try the normal typeface, and use the lightest touch that preserves the meaning. Another option is to indent actual quotations, as I did in repeating Searle's words, but visual separation like this is not clearly better than quotation marks.
Using et cetera is dangerous, as it is easy to vaguely imply there are more things in a list while the reader may have no reasonable way to guess these things. When used poorly, it conveys that there is more to know, that the author knows it, that it should be clear to the reader, but isn't. In his Tractatus Logico-Philosophicus, Ludwig Wittgenstein, while speculating about symbolic representations, says:
If we were to try [a specific idea using variables to symbolize ideas] ... we could not determine the identity of the variables, etc.
The use of et cetera here strongly implies that there are other problems, but it's not clear what those problems are.
In general, it's bad to hint at something the author knows but the reader must guess. It may be tempting to either sound intelligent by dancing around ideas, or to assume the reader has the same background knowledge as the writer. Both approaches conflict with clear writing.
Write so that any intelligent person can understand. If you succeed in communicating well, then some of your readers will be more intelligent than you. Some will be less intelligent, but perfectly capable of grasping your core ideas. Write so any of these readers can follow your thoughts. Appreciate that some may find value even when they disagree with you.
In Thus Spake Zarathustra, Friedrich Nietzsche wrote:
And Zarathustra thus spake unto the folk: "I teach you beyond-man. Man is a something that shall be surpassed. What have ye done to surpass him?"
Nietzsche, in the words of Zarathustra, goes on for a bit about how awesome the beyond-man is, and how this beyond-man is the way of the future. What he doesn't do is explain why he thinks this is so. The attitude of the text is like a biblical story couching a presumably deep lesson – a lesson we are lucky enough to learn about, as if it were a secret spilled by a reluctant prophet.
This style is nearly the opposite of respecting the reader.
The goal of good writing is to communicate ideas that many readers find worthwhile. The most worthwhile ideas are convincing ideas – thoughts which the reader accepts as true. But truth is not a necessity in communicating ideas. A reader may still disagree with some of the writing and find value in the ideas they do find compelling.
In Plato's dialogue Laws, he suggests that the ideal state would have 5,040 citizens. He likes this number because it is evenly divisible by 2 through 10, and by 12 – so it's easy to split things up evenly among this many citizens. I do not find this argument particularly worthwhile, but as a reader I still find value in reading Plato's dialogues because of his many thought-provoking arguments.
Ultimately, writing is not about the writer. The successful end result is a reader enjoying what they read. It is a chance for new ideas to come to life. Traditional writing styles and natural human ego tempt us to write presumptuously. Your readers and your ideas implore you to resist!
The path to good writing is long and difficult, but the mark of success is simple to state.
Write clearly. And respectfully.