This particular Facebook polemic exhorts us to "question everything."
Why? (<-- Get it?)
Facetiousness aside, let me make a few prefatory remarks. I am sympathetic to investigation. Personally, I love learning. I consider myself very inquisitive. And I would never stifle the innocent and genuine questioning of a child.
However, "question everything" strikes me as a sort of platitude that, while it sounds like a high-minded and enlightened thing to say, really is both logically problematic as well as utterly impractical.
One way to construe the principle is as strict and literal advice. Taken literally, "question everything" would launch one on a vicious infinite regress. One would literally believe nothing whatsoever, entertaining only iterative questions.
For example, and so that I may not be accused of special pleading on behalf of pet theistic conclusions, no one would ever get to the point where one would be justified saying, "I believe that atheism is true." This is because, at any point one wishes to sample, there would always be only a question. One would forever be questioning atheism; or questioning one's questioning of atheism; or questioning one's questioning of one's questioning of atheism; and so on, ad infinitum. (Note: I am not endorsing atheism.)
There is no room on this view for concluding anything - ever.
I do not think that anyone actually does function this way. In fact, I suspect that it would be practically impossible to do so.
Therefore, the "question everything" model, if taken strictly literally, appears to be nonsensical.
There is another way to take "question everything." One could, for example, take the phrase as a label for some sort of sophomoric, adversarial game, like kids who just reiterate "why?" questions to be pains in the ass.
I take it that this sort of "questioning" may be summarily dismissed. It is patently unhelpful and disingenuous.
Although, perhaps this is too quick. Possibly "question everything" is merely intended to be a heuristic device. Maybe it is simply an abbreviation for some generic encouragement towards learning.
I can accept the principle if it is taken in this qualified sense, as an encouragement towards learning.
Note well, though, that because no one can entertain only an infinite regress of questions, it is necessary to model the sort of learning that we are encouraging in a way that does not take literally the exhortation to "question everything."
Elsewhere, I have drawn a sort of analogy to hunting. There are (at least) two types of hunting. Let's call the first type "sport hunting." If one is "sport hunting," then it doesn't really matter if one catches anything. So too, in the sophomoric question-parade, the aim seemingly isn't anything other than to entertain oneself, pass the time, or, in the worst case, to disconcert one's interlocutor.
The other type of hunting, however, might be called "serious hunting." In "serious hunting," it matters quite a lot whether, in the end, one catches anything or not. If one fails to catch something, then one's hunt has not been successful. In this way, serious hunting is akin to serious questioning.
In my view, serious questioning aims to discover the truth. This is not to say that the truth is easy to discover. But it is to say that when we state the the aim of asking questions, we will do better to say that - in principle - the aim is to get the correct answers. For anything less than this aim is either a childish game or a futile and endless endeavor.