If you ever meet a self-called PhiloSopher,
just ask him his definition of PhiloSophy: no problem, there are three dozens of them in the Big PhiloBook, (imagine 36 definitions for blood or AIDS). I have added some more, quite different, (but I stick to mine "Bases to Think") And I could add thousands deduced from the behaviour of "so-called philosophers", especially in the "satammist world".
    Then, you ask him: "In fact, a philosopher studies what is left by the others, he takes care of "lost dogs"? you try to understand the phenomena nobody care for, when everybody thinks it's lost time? ? like "Why we exist?", "Why there is a Being and not Nothingness?" ((I like the search for the "King of France that is bald", or for " Snow is White, IF snow and IF white...")
    Your "philosopher" should be glad as an abstract painter hearing: "Your painting is awfully tormented. Your have painting living human suffering...) Or, as clever as an unmasked inconsistent Politician: "Exactly what I have just said!, differently..."
    As some "newcomers" could be among the readers, I don't lose an opportunity to show them the stupidity of 'sorboniSophism". Since Locke, and Kant, (and Arthur!) it is admitted that there is a "reality" that we try to grasp with our senses  and our reason. Up to what point we succeed? Impossible to say. But any Sophist pretending to grasp Great Being, is just a joker, and more: a "satammist", ("Being" is a variant for God, Infinite, Absolute...). Why do we set this problem of Being? The animals have not this problem, because they have not a conscience. So the correct setting should be: "Why Man and not only Animal?" or "Why Conscience and not just Instinct"? That is what is carefully avoided by shittoSophers, Ltd. But it is  the way to solve "autism". Now, what do you expect of this "Theory of Mind"?
Now, let's cook our undefined philosopher: "Let's say you establish the conditions, the "bases of correct thinking". Therefore while defining philosophy, you use a tool. A good worker starts by preparing his tools? Could you give your definition of "definition".
Spinoza spent some nights on this difficult problem, but his setting was quite wrong: "To make a hammer, you must have a hammer..." Néant-der-Thal had immediately solved this hard problem with a big pebble and a stick. In the soft world, (always think of their parallelism to be creative), it's not so easy: Godel had a definite opinion on any possibility to solve such problems...
    But for falsoSophers impossible problems provide a refuge, jealous of the dermatologists, (and some autism-wizards), blessed with patients that don't die but never cure: "Why Being and not Nothingness?" instead of "Why Conscience", which lead rapidly to "Where do I come from, where do I go?" Some create a "church" other turn years around the bush, in a campus and proclaim themselves great explorers...
    We makes mistakes, some of them expensive, irreparable even after our death. And we chew: "How could I avoid it?" That's "pure philosophy", the start since rapidly we ask: "How could I use my mind in a better way". You don't need mistakes, just a need to solve a personal problem. I thought for a long time that I had this special knack at solving any problem, because of the war. When 13 years old, I live the collapse of France, and of bright fellows, that could conquer Berlin in three weeks, with a bayonet. Then at 17 years old, I live horrors, people were shot for their opinions, (some deserved it). I was even required as a choir boy at a strange burial: two coffins and just a prostrated woman, repeating: "I understand for the father, but why the son?" The father had fled with him thinking a boy would protect him from immediate shooting. Both were shot in cold-blood. We were at some kilometres of a prison made famous by a film, (the "Franciscan of Bourges", the fellow that during the night cured people for a last day of torture, when people break easily...)
Therefore, anybody is a "philosopher", but some "privates" are more so than "professionals". It depends on your motivation and on your preparation, on your "material". Have you noted that, contrary to mathematical geniuses, philosophers appear in their old age, (I know some exceptions, my "autiswin" Arthur, or in a lesser degree, Comte, Wittgenstein...) A mathematician find his "material" in books: with imagination, he can be rapidly brillant. True philosophers find their "material" in the world: difficulties in life are a good medicament, like living revolutions, ((Locke) or wars, (Wittgenstein, Popper) or "madness", (Comte, Jung). The worst way is "Sorbonne".
    I pretend that, among retired people, we have ten thousand more people prepared for true philosophy that among all the "shittosophers" made in "Sorbonnes". I repeat: "modern philosophy was re-launched by a retired fellow, full of experiences, name Locke, (I regularly met this kind of problem in enterprises: for industrial costs, should we take an engineer , (that doesn't know accounting), or an accountant, (afraid of workshop)?) Locke just wondered: "How did Newton's brain function?" Poincaré, (that gave MV2, (M for "mathematically")), was still on the problem when he died, without more success, (I have not enough material to decide whether Poincaré was "top-autist"). Strange, Einstein did not care: he could explain, sure.
    "Philosophy", seen from outside, is a strange matter, always dying under general scorn, then reappearing like this Phoenix bird. We can settle this strange fact, with a simple description of true and false philosophy, explaining why, since millennia, so many non-philosophers-at-all demand and rob this label. But I don't want to revive true philosophy, that would be immediately in the claws of "sorboniqueurs". I prefer a new word like "bases to thinking", even to the point of never writing a "philosophy". Demonstrations will be enough. And I made some in all the domains of knowledge, some really bloody.
    To conclude, "defining the definition" is strictly impossible. So, let's use a trick with a first definition: "
The quality of a definition depends of
the quality of the definition of its environment".
    Danger! we are falling into Xenon's story of the tortoise! I know. So I won't stop at the second step. I'll continue to the last environment.

Therefore, at the end of our research on the "definition of the definition", we'll have a terrible tool for judging "squattosophers", sitting on the roadside, "book-makers" happy to make money, ("Publish and get Rich!", with honourable mention to Nobel Winners, Bergson and Sartr'Or Resartus), demanding "consideration" from the "lower-thinking classes in need of a Guide", (in France we even saw them, in their strange clothing, in the street like lorry-drivers). At the end, everybody will be judged on the "noodigm" he used as a thinking base, often unconsciously. In my opinion, today, the best noodigm is the 4th, (established by Darwin). And then we'll establish a simple, very convincing, schema of "philosophers" and each one will be judged according to his "remnant of satammism".

So, we find three "schools " among philosophers:

- True ones, that really needed to understand, (Locke, Hume, "Arthur",...), many of them "scientists" by formation, (Whitehead, Kant, Comte,...).
- Then, "commentators" for any reason, finding their fodder in books, able to explain even Great Being, teaching on a campus, (but not teaching the indispensable criticism to their students...), thousands of them during 5000 years...
- Then last but not least, the true geniuses that changed our knowledge of the world if we accept this definition of philosophy as an "unending quest of bases to think":. Newton called himself a "philosopher", then Darwin, "the creator of psychology", Poincaré, (that gave MV2?) , Einstein, the Brain of this Century... So, "philosophy" and "science", (that were separated, for "religious reasons", at the "Renaissance"), are reunited to create a true civilisation, (no more confusion with "civisations").
    Many "top-autists" in the world of Art, (but I prohibit "genius"), with a great difference to understand "top-autism", "the people that chose a different evolution": more suicide among the artists than among the "savants pas idiots".
    A "top-autist" is surely prepared for "philosophy", like for any solitary job, (from Painting to General Management). In my case, a layer of "prosopamnesia" was added as a super-protection. More: for circumstances, (never seen before and not to occur again), I was specially prepared to "problem-solving": I was taught a "philosophy without any philosopher". That's why now, I would like a "philosophy without any paper", pure problem-solving.
    Every thing was mysterious in my training; full of puzzles to be solved alone, (top-artists are quite good at this game). From 12 to 22, I was in contact with, (observing, helped by, pushed-pulled by), first class brains but I'll never know why or what for they really built me.
    God writes straight with curves: my four "locomotives" disappeared rapidly, three of them by violent deaths. At least, I hope to convince you on the importance and on the possibility of creating your "bases to think".