Not profound

I feel the need to post more cartoons, to make up for my recent absence. (Matt, take note!)
The cartoon requires some explanation: technically speaking, philosophers don't "just make stuff up." However, in searching for a definition of philosophy that could capture all the different things that have fallen within the bounds of the discipline, from Thales' speculation that everything was water, to Descartes' Cogito ergo sum, to Isaac Newton's "natural philosophy," to J.L. Austin's How to Do Things with Words, and so on... (this list is intended to show how wildly disparate the subject matter can be, not list favorite philosophers), I've come up against the following question: what do they all have in common?
Each is trying to answer a question that can't be "looked up" or tested. (Newton's laws are an interesting case in point: they still seem true, even though Einstein showed that they weren't). In the absence of an empirical method to test the theories (or divine revelation, which is typically discounted by philosophers), we use can reason in order to form a hypothesis to answer our question. Hypotheses must meet certain criteria, including offering a plausible answer that adequately explains the subject in question. But the subject doesn't matter as much as the method, thus, this method of approaching questions is the essence of philosophy. (It also explains why the "perennial questions" never get answered, and why philosophy as a whole is so easy to spoof: anything that gets a concrete answer ceases to be within the realm of philosophy.)
I guess all of this is merely a long, unnecessarily footnoted way of saying, 'yes, philosophers do just make stuff up; but they do so within a certain framework, according to rules that have been refined and handed down over thousands of years.'
Of course, that doesn't make what we say true.