Most philosophers still claim Socrates as the first of their trade. Socrates recorded no words of his own (at least, none that have survived), wandered around Athens having conversations with people, and frustrated everyone with his endless questions and original ideas. Folks said he was wise—he said if he was indeed wise it was only because he knew that he knew nothing.
Wisdom, however, was his chief object. He didn't earn the nickname "Gadfly of Athens" simply because he liked causing problems; Socrates wanted to know the truth about things, about (to quote another philosopher) "life, the universe, and everything," and to understand how that knowledge should and could affect everyday life. Hence his more lasting title: philosopher, a combination of the Greek words for love and wisdom.
Modern heirs to Socrates also claim to be lovers of wisdom. They make a big deal about that, in fact, and even hint that without people like them the rest of us would just be floundering along in the dark. That's because most contemporary philosophers aren't exactly telling the truth—they aren't out to obtain wisdom, they're out to construct Truth.
The change came during the first half of the 17th century when a French philosopher named Rene Descartes developed a way of doing philosophy that was directly at odds with Socrates' methods. It was more the style of Aristotle, and could be traced to Descartes through the voluminous writings of Thomas Aquinas, but Descartes made it wholly his own and changed the entire philosophical landscape single-handedly.
He called his approach "philosophy from first principles." Essentially, this method meant the abandonment of all reliance on authority as a starting place for philosophical endeavor. Descartes thought he had to start from what he could know to be true through his own reason and observation or else the whole system would fail.
Philosophers ever since have taken this as the rule. To be coherent, they say, a philosophy must start from the ground up. What they usually overlook is that Christian doctrine provides exactly the kind of framework they're looking for. But, because they can't accept Truth isn't wholly apprehendable by human reason alone, they reject it, and wallow in their own "intelligence."
This probably sounds like we're altogether against philosophy. We aren't. What we are against is the secular attitude that Truth can be uncovered or constructed by human reason. Truth belongs to God, and our duty as Christians is to understand it as best we can through the agency of the Holy Spirit and God's Word.
When philosophers do this (men like St. Augustine, Soren Kierkegaard, and Francis Schaeffer), they're doing philosophy right, and showing themselves to be the true heirs of Socrates whose goal was wisdom. That doesn't mean we shouldn't study secular philosophy, but we should only do so carefully, and with the intent of countering non-Christian ideas with those rooted in Scripture.
Most of the titles we carry are from an orthodox Christian perspective. We do have a number of classic philosophical texts, but overall our approach has been to carry overviews and critiques rather than a lot of source material. As with any discipline, constant prayer and self-examination are crucial when learning about the ideas that have shaped culture and history; they are, after all, only imperfect commentary on God's world and work.