I'm an elitist. Some time after becoming an academic, I started to think that most (non-fiction) writing by non-academics is no good. Most journalism and trade books, for instance -- I think they're intellectual junk food. Untrustworthy, lazy, not-to-be-taken-seriously.
Now, you might be tempted to think: "Oh, the academic world is just a big, intellectual cartel. You're just trying to protect your cartel's control over ideas!" Maybe. I mean, that's one possible explanation of my thinking. Another explanation is that maybe people learn stuff through academic training. Stuff that you need to know to do worthwhile work. I'm just telling you how things strike me.
Most people recognize expertise in the natural sciences. They would not attempt to write a book on chemistry without academic training, nor would they read such a book by someone else.
There are, however, quite different attitudes about both philosophy and politics than about science. No one needs special expertise to hold forth on those things. People think the fact that a question is philosophical means that they can hold whatever view on it strikes their fancy, without paying any attention to what anyone else has said about it. A book of philosophy or politics by a celebrity, or a priest, or a politician, is perfectly saleable.
Not to me, though. I think it's so unlikely that such a book would be of any intellectual value that I would basically never open it.
Notice that I'm not saying you have to agree with whatever most philosophers say. I am saying you need to understand what most philosophers say about a (philosophical) subject before teaching other people about that subject. In this field as in any other, if you don't know the received views, then it is virtually impossible that you're going to do anything useful.
Why is this? People have been doing philosophy for 2,000+ years. Many, many people have thought for a very long time, and written a great many books. The only way it could be that you have nothing to learn from that would be if either the rest of humanity are morons, or you're the greatest f---ing genius in the history of the Earth. In the latter case, you should tell the rest of us the key to immortality already.
In case you're about to say that philosophical "experts" are not very reliable at getting philosophical truth, note that this doesn't mean that you (or some other non-expert) are reliable. People who don't even have the expertise of the professional philosophers are probably even worse.
Sometimes, people who lack philosophical training write books and essays on philosophy. These books and essays are usually very bad. (Sorry, Objectivists!) Which, by the way, leads to my advice: if you want to write about philosophy, and you want what you write to actually be good, spend several years studying philosophy. Not pop philosophy, professional philosophy.
Now, if you're inclined to resist my claim, think about the common sense point. People go to graduate school, typically for six+ years, after a 4-year undergrad degree. What do you suppose they're doing, just sitting around doing nothing? If you spend six years studying something, do you think you're going to learn nothing of any import about it? Would your thoughts at the end of the time be no better than at the beginning? Also, if you do so, will you be able to tell someone else, in a few minutes off the cuff, what you learned in the 6 years?
I hope you answered "no" to those questions. If so, you can maybe understand why philosophy books by non-philosophers are typically not good.
Q: What if you study philosophy on your own; isn't that just as good as studying in a university?
A: No, it isn't. The problem is, some of the things you have to do in order to grow intellectually are hard work, and not really fun. Professors make you do it anyway. Self-taught people virtually never do such things. They virtually never get in the habit of doing the onerous parts of writing that are necessary for careful scholarship. Non-academic authors will not do anything like the amount of research, and will not make anything like the amount of effort to document their claims, that a good academic scholar does.
They will not spend dozens of hours going through literature by other people to make sure that they're being fair to people they completely disagree with. Or to make sure that their argument hasn't been rebutted by one of those other people. Or to make sure that there aren't factual details they didn't know about that they should modify their ideas to take account of. Because none of those things are fun.
And that's why their writings are just not intellectually good. Most journalism and most popular non-fiction trade books are intellectually irresponsible and trashy. The problem isn't that the authors are stupid, and the problem isn't that they challenge received views. Overwhelmingly, the problem is that they are lazy. They only do things that are easy. Which is precisely what readers don't need.
Not that academics are never lazy. Humans get lazy when they think they can get away with it. For examples, see these book reviews (the examples of laziness are the books reviewed, not the reviews themselves): http://static1.squarespace.com/static/520cf78be4b0a5dd07f51048/t/53a029dce4b0ba2ac791103b/1403005404701/Strohminger.EmotionReview.2014.pdf, http://philsci-archive.pitt.edu/11195/1/MindReviewL.pdf. The former book has 16 entries in the bibliography. (That is a very small number.) One can pretty much infer that the book is worthless, since the author was too lazy to do serious research.
But while academic authors are sometimes lazy, non-academic authors are almost always lazy. It's human nature. We want to blabber out our own thoughts, and we don't want to have to sit there reading tons and tons of other people's thoughts first.
Case in point: this blog. It's lazy; there are hardly any references. You should probably ignore it and get back to reading academic articles.