Too many people are willing to set aside critical thinking for convenience. While the issue isn't just limited to the pagan community, that's what I'd like to touch on just a bit today.
Lately I've been seeing a shocking number people willing to accept information, without considering the source of the information. They see something that fits in with their preconceived ideas, and leave it at that. This is a bad place to stop, it's important to consider the source of the information - how reliable is this author, when was this written, was it written for a specific audience?
Let's look at each of those. As the saying goes, even a stopped clock is right twice a day, so even the worst sources will be right on occasion. Still, if a source has a record of being wrong quite often, it might be best to question the information they give. Use multiple sources, use good sources. Likewise, we shouldn't be afraid to check on an author's credentials. Do they relate to the topic they're writing about? Are they consistent with their credentials?
It's important to consider when something was written, as sometimes new information has become available in the time since the writing. Let's look at the Egyptologist E.A. Wallis Budge as an example. He did a number of translations and wrote a number of books until he died in the year 1934, and many of his books are available for free online. Since his time, we've made huge leaps and bounds in translation and method, so there are much better sources now. Still, some people fall back on these older, less reliable sources. They put this incorrect information out there for others. Bad history is a big problem through the pagan community, but it really doesn't have to be if we just took a little care in examining our sources.
We also need to consider the audience the work was originally intended for. This usually won't be an issue, but can be with older works. Sometimes a work claims to be intended for a specific group, but was really targeted at a large audience. Sometimes a work claims to speak for pagans as a whole, but really focuses on one tradition. This sort of thing might not always be obvious, but will usually pop up when looking into the author.
Don't accept something just because it was written in a book, on a website, or anywhere else. Don't be afraid to question. Use multiple sources. Weigh out conflicting information, don't just accept what you came across first. Of course all this is but one aspect of critical thinking, but perhaps it would be best to save some of that for another day, rather than writing one giant post...