By “clearly written” I mean things like that the text should not casually use undefined terms or phrases, — tinman917

Well, I think that this is a readily fixable philosophical mistake. You are using "clearly written" as a universal standard. What is "clear writing" to an audience of nineteenth-century German academics, where everyone has read Greek by age 8 and has read Hegel's Phenomenology like it's the bible (and thus adopt its terms), is not going to be "clearly written" by your standards. The same goes for someone sitting in Athens 2,500 years ago, Florence 600 years ago, London 400 years ago, Copenhagen 150 years ago, etc. etc.

The example you use (Levinas) is working within a rather insular French intellectual context in which that's simply how people write philosophy.

If not then what am I doing wrong? — tinman917

You're expecting to study philosophy on your terms. You want philosophical texts written across the whole spectrum of possible human contexts, modes of thoughts, areas of interests, etc. to conform to your way of thinking and reading. You need to adopt philosophy as a journey which expands the horizon of your ways of thinking, reading, writing, etc. etc. or instead stick to contemporary academic articles and secondary-sources. (And I can say for certain that some professor in the US or UK has packaged Levinas's thought into precisely the sort of prose you seem to seek.)

Do others find this as much of a problem as I do? If so how do they get round it. — tinman917

Well, I can tell you it does get easier. I have noticed especially recently that, after 10 years of serious study, my reading comprehension has gotten much faster and I struggle a lot less with texts now that I know the terrain fairly well. For example, if I read a phrase like "inferentially articulable doxastic commitments" I'm familiar with the words, the concepts, how they have been used by a variety of philosophers to make a variety of points, etc. But it takes a long time, at first, to truly understand why people are using the language they do, the concepts they do, and what it all means -- how one ought to interpret that use for oneself.

What John Doe said.

And, reading Kant (for example) is like lifting weights and running up hill. Difficult at first but it gets easier, as John Doe suggests, and then relatively easy. You get the real effect when you turn to something else that seemed difficult, maybe like Shakespeare. Zoom! No problem! It's actually amazing the difference (in my real, actual experience).

More seriously, there is a kind of open plasticity of mind you have to have to read philosophy, and probably a lot of other subjects, at a technically competent level. It's more than a familiarity with terms and ideas. Perhaps it's more like an ability to relax and roll with the text. In any case, Mortimer Adler wrote a book titled How to Read a Book, that details techniques for how to attack a book that at first read seems impenetrable. Spoiler alert: it requires work on the reader's part.

And it is this last that probably matters most: the need to work at it. It's real work: it forces a gut level decision, is it worth it? There is a lot of obscure philosophy that's little read. I think it's not because it's difficult, but rather because it's not worth the effort.

The first sentence of the text is “Everyone will readily agree that it is of the highest importance to know whether we are not duped by morality.” My first thought was: no, I don’t “readily agree” to that. Because I don’t know what “duped by morality” means. And neither do the succeeding sentences cast any light on the meaning. — tinman917

I see your point, and then some. Sometimes you just need to be charitable and let certain things slide. I would approach the above with "Okay, humor me." Then, keep on reading. The hardest thing to read is not the most difficult to comprehend -- on this you could get help from other philosophers as they each refer to each other's work. The hardest to read is one that turns your strongest beliefs into futility or uselessness (I hope schopenhauer1 is not reading this).

Imagine that.

Anyway, @tim wood and @John Doe have some good things to say.

The first sentence of the text is “Everyone will readily agree that it is of the highest importance to know whether we are not duped by morality.” My first thought was: no, I don’t “readily agree” to that. Because I don’t know what “duped by morality” means. — tinman917

Why make difficulties about this? I like to take a naive view that folks mean what is generally meant by the words they use, unless they go out of their way to redefine them, or problematise them. So I assume 'everyone agrees' is not a universal claim that you have disproved by withholding agreement, but an indication that what follows in uncontroversial and fairly simple. So morality is some conglomeration of strictures about how one ought to go on, that is current and seeks to impinge on one's life - such as 'you ought not beat your wife'. And one is duped if it is actually just fine, if not a solemn duty to beat one's wife. And if I have spent thirty years doing the wrong thing or depriving myself of a simple pleasure, thinking it was the right thing, that is a tragedy of the highest importance for me.

I don't know Levinas much, so I could be wrong, and if I read more, I would probably find out, and if I did turn out to be wrong, then I would feel it appropriate to fulminate about his lack of clarity.

“Everyone will readily agree that it is of the highest importance to know whether we are not duped by morality.” — tinman917

If this really stumped you, your case is probably hopeless and philosophy not for you, frankly.

(Edit: Sorry if that sounds unhelpful. The point I wanted to make was that I doubt it really stumped you and you are just being pernickety about understanding.)

Here's a more representative sentence of difficult philosophical writing that I happened to have just read:

"Here we encounter the key formula: Kierkegaard's God is strictly correlative to the ontological openness of reality, to our reality as unfinished, "in becoming"."

(The Parallax view - Slavoj Zizek)

Stuff like that slows you down, but not interminably if you know the vocabulary, and in slowing down it forces you to think. Which is the whole point. I'm sure it could have been made simpler but not at the expense of many more words (in an already very long book) and the philosopher in question doing most of the thinking for you (at a level below his).