What is a Philosopher?

My Definition
A philosopher is a person who applies critical thinking to foundational bodies of knowledge. What makes a body of knowledge foundational is that other bodies of knowledge tend to rely on the assumptions found within those foundations.

For example, epistemology is a foundational body of knowledge as all bodies of knowledge deal with concepts like truth, belief, knowledge. If you were to challenge, say, physics, you may end up challenging science and ultimately epistemic foundations. Challenging epistemic foundations are... just challenging epistemology, again.

While the typical topics of philosophy, Language, Epistemology, Metaphysics, Ethics, Mind might argue who comes first, who is most foundational, these topics are all near the base of the foundation. Many may take that to have a coherent view of one, one must also have coherent views of the others. I won't try and argue for any of that, I merely want to establish, on my view, what philosophy is.

Analytic vs Contintental
To me, analytical philosophy and continental philosophy both have the same aforementioned goal, to critically evaluate foundational bodies of knowledge. What distinguishes them is their approach to doing this. In broad strokes, analytic philosophy seeks to do it directly. I do the thinking and then explain it to you in the most direct way possible, so that you may know my thoughts. The continental tradition attempts to elicit knowledge within the reader indirectly, creating an environment so that you may come to the conclusions about these topics yourself.

Is there non-foundational philosophy?
What about the philosophy of love or science?

Yes, of course, there are philosophies that don't go all the way to the foundations. Yet, they tend to be either very close to the foundations or applications of them in a specific way. Take the philosophy of science, for example. We have an activity called science, which is the target of the philosophy, but it uses epistemic ideas to investigate it. One may say that it is epistemology directed at a specific phenomenon. So either way, philosophical topics remain at or near the foundations. Whenever a topic has too many foundational assumptions in order to function, it leaves philosophy and becomes a new body of knowledge. Note: The foundational assumptions that non-philosophical bodies of knowledge operate under don't have to be realized, they are often automatic.

Types of Philosophers
Pure Philosopher - Yes, this is a bit of a self-aggrandizing name. A pure philosopher is a person who will spend time to critically evaluate any position. Anything they hold as the case is up for debate and critical analysis. That doesn't mean they don't hold bias positions or that their positions are the most defended and most thought out. "Pure" doesn't mean "skilled" here. One might say that a pure philosopher is someone who holds a value for critical analysis that is stronger for other values that would prevent them from doing so.

Impure Philosopher - Much like impure metal is a metal with other elements mixed in, an impure philosopher is one who critically evaluates positions while holding on to some assumptions they will not evaluate. Much like any metal, to be reasonably called that metal, must not have too many impurities, to be a philosopher, even an impure one, would mean that you do not have too many unchallengeable assumptions. An impure philosopher may hold certain positions as too important to them to ever consider up for debate, but none the less do good work challenging other beliefs.

Sophistic Philosopher - The sophistic philosopher is someone who uses critical analysis and may be very skilled with it, but only when it serves other values they hold. Often, it is social values that motivate this person. Perhaps they realize that some of their positions have weaknesses, but will not speak of them, lest their public image is tarnished. They are happy to bring up the weaknesses in positions of those who disagree with them. They also tend to spend time learning rhetoric skills to supplement any weaknesses in their own positions to combine with their philosophic skills. These people will only spend their time using critical analysis if it somehow advances something other than their value of critical analysis itself. While the sophistic philosopher is not unskilled, a resistance to genuinely explore their own weaknesses or admit them leaves them as stunted potential as philosophers. (Which may be fine to them, since it is not their ultimate goal anyway).

Historic "Philosopher" - This is the sort of person who has a lot of knowledge about philosophical positions, enjoys talking about them, but doesn't really engage in critical thinking about them. They may advance a position in a conversation, but if asked questions that challenge the position, they show very little interest in analysis. I don't consider this position a real philosopher, hence the quotes. However, they may really look like one.

While I did write some hard categories here, I would suggest taking them in degrees. We are probably all a little sophistic, even if we don't want to be. Some people really pop out as being completely sophistic, while others are only mildly so.