Before I can explain what the philosopher is, however, I must explain who a philosopher is. The simple definition, of course, is to define a philosopher as one who studies philosophy, coming from the Greek words meaning, "love of wisdom." Philosophy of course can take many subdivisions, but I will make the claim that most will agree that what all the divisions have in common is their search for truth.
These things alone do not make one the philosopher though, for there is something greater required to be part of the universal philosopher (I'm being very Platonic with my participation idea here). To him belongs the burden of defending the nobility of philosophy. For the true and complete philosopher, philosophy is but a means, it is what he uses, not only what he studies. I will hold that to be the philosopher carries a three-fold requirement: to study everything which pertains to the science of philosophy, to give, and most importantly, to contribute.
To study everything which pertains to philosophy of course means to study everything, not just within the subject of philosophy, but within all subjects. For all subjects have truths, which of course will contribute and be necessary in the study for Truth itself.
Now, I do not propose that anyone is capable of studying and knowing all things. This idea is not only preposterous, but it would make for a very boring social life (or maybe for a very interesting one, depending on how one goes about it). To accomplish this does not even require the philosopher to actively seek out the knowledge, but he must be open to knowledge. He must always be desirous of new information.
It is necessary that the philosopher be able to answer adequately all the claims brought against him. When a new discovery is made in science that seems to contradict the truths of religion, it is the philosopher's job to refute those claims by reconciling the two. This will of course require him to study both fields, so that he may know what each contributes to the argument. Although he may have a special area of focus, say the study of the soul, he should be able to apply his philosophical knowledge to answer a question in metaphysics. This he is capable of doing because philosophy has given him the method to do so. He will appeal to the experts for assistance in this task, for from philosophy he should have learned how to study and formulate an argument. And lastly, he will hold steadfastly to the truths he has discovered, but he will never turn away an attack against them. Nor will he simply argue against and disprove it. But he will look at it, and find the truth to it, and at least offer the claimant the ability to reconcile it with Truth itself.
The next requirement for the philosopher follows from this - the philosopher must give. I do not give a direct object to the verb "give," because it can take so many. The philosopher must give instruction, he must give opposition, he must give support, he must give clarification, and so much else.
The philosopher cannot be content simply with studying the science. Although I will not hesitate to say philosophy is worth studying simply for itself, this simply makes one a philosopher, not the philosopher which we are working towards here. Rather the philosopher wants to pass on what he has learned and discovered. Therefore, he will teach others; not necessarily in a university, but at least the basic truths will be upheld in everyday life and given to others as they may benefit from it.
He must also be willing to give opposition, for the claims of philosophy are as numerous as the stars in the sky, but the earth has only one sun. The philosopher can never allow other claims to be seen as equally worthy, for that would be the denial of Truth, which consequently is the denial of God. Therefore, he must oppose and refute those claims, not with hostility of course, but with the utmost charity, always keeping Truth before his eyes.
From this it also follows that the philosopher must lend support and clarify. He does this to all who are seeking Truth. To those who have found the Truth, but struggle to grasp it fully, he lends explanation. To those who have yet to find It, he clarifies. Due to the necessary precision of the science, the meaning of the great philosophers is often not readily understandable. Additionally the differences in writing styles over the ages make it hard to translate and understand them. Therefore, the philosopher will clarify what they mean, correct distortions in other interpretations, and even correct the greats when necessary, not destroying their system, but rather aiding it.
Before, I go on to the last point, I must explain the concept of the philosophia perrenis. This we could call the Truth. It is not a specific system of philosophy, but is rather contains within it all of the truths of the universe, and the best methods and ways of explaining them. All philosophies draw on this and contribute to it in greater or lesser degrees. It endures, because it cannot be destroyed. Philosophers may diverge from it, but they must always return to it. And it is this perennial philosophy which the philosopher has as his last goal.
Now, lastly, and most importantly, I say that the philosopher must contribute to philosophy. This is the most important because it is the hardest. Thus, it is the rarest, but it is what makes one the philosopher! To contribute is not simply to give, because by "to contribute" I here mean that the philosopher must give of himself. He enters into what Robert Maynard Hutchins and Mortimer Adler refer to as "The Great Conversation." It is a discussion that began when history began and will go on to the end of time.
This is a great shift which we see in many of the modernists. They do not value the works of many previous philosophers, just their specific teachers, and often not even those. I think specifically of the trend in universities to ignore and deny that Scholasticism is a philosophy. I can respect your choice to disagree with the Scholastics; I find it hard to respect the choice to deny an evident truth. Call them bad philosophers if you will, but at least call them philosophers. I do not hesitate to call Nietzsche and Peter Singer philosophers, even if I do not agree with their methods or premises. Aristotle did not agree with Anaximander or Pythagoras, but he called them philosophers.
I want to state my belief that Aristotelian and Scholastic philosophy, primarily Thomistic philosophy, best embody what I mean by the philosopher. The main argument that modernists will make against these systems, primarily Scholasticism, is that they are integrally tied up with religion. I will not deny this claim. But this supports the points I have made above - philosophy must use all sciences in its support. Since both religion and philosophy seek truth, it seems logical to use them together. Philosophy can't give revelations, but it can support them. Additionally, Aristotle is known for all of the work he put into biology in his philosophy. Although he was incorrect in many things, he used other fields for his work and I praise him for this.
A small handful of other contributors to this Great Discussion in philosophy are Thales, Parmenides, Heraclitus, Plato, Augustine, Origen, Bonaventure, and Benedict XVI. Like I said, it's just a handful.
It would instantly seem that I skipped two ages of philosophy - the modern and contemporary eras. There is a reason I did not include philosophers like Immanuel Kant and Rene Descartes. It is not because they are not part of the Great Discussion, but because they did not contribute, but rather attacked it.
better than endeavor once for all to sweep them completely away, so that they might later on be
replaced, either by others that were better, or by the same, when I had made them conform to the
uniformity of a rational scheme.
advance we are to find the solutions, to call into council the views of those of our predecessors
who have declared any opinion on this subject, in order that we may profit by whatever is sound in
their suggestions and avoid their errors.
I can praise the modernists for wanting to incorporate science into philosophy, but they unfortunately often make the error of believing philosophical truths will come from science. Rather it is the other way around. Philosophy is the science which gives meaning, purpose, and principles to all the other fields.
This is an arena in which the philosophers of today have an opportunity to make their contributions. They have the opportunity to reconcile science and religion, to purge the errors from all of the schools of philosophy and guide them to the perennial philosophy, and to bring philosophy into the public sphere to heal the wounds gripping society.
This then is what differentiates the philosopher from the majority of philosophers. He wishes to guide the world to God. Whether he does it consciously or unconsciously, he seeks to bring unity, truth, and goodness to philosophy and to society. These of course are all attributes of God.
I feel it appropriate to end with my favorite quote of Aquinas, "The purpose of philosophy is not to learn what other men thought, but to learn the truth of things."
Our Lady, Seat of Wisdom, Pray for us!
St. Thomas Aquinas, Pray for us!