The canon of Western Philosophy is interesting because it forms a pretty clear story. The early Western philosophers, the ancient Greeks, were rationalistic and deductive. The medieval/renaissance philosophers were basically Catholic theologians. The modern philosophers were empirical, skeptical, and secular. The late modern philosophers were atheist and starting to toy with relativism. The most recent philosophers are postmodern, which means they are hard to categorize but are generally relativist, deconstructionist, and anti-modern. Some continue in the atheist tradition but some are spiritual; many are anti-West.
So the general trend of Western philosophy has been from metaphysical and rationalistic to anti-metaphysics and empirical. Or, essentially “religious” to non-religious. The good news is, for the Christian philosopher, that the new postmodern landscape provides a good context for religious discussion to re-enter. Because philosophers are pluralistic, they may tolerate new systems. If the theologian can form his arguments in a non-religious way, his ideas may be welcome.
This brings us to the idea of Reconstructing the Ivory Tower. Centuries of Western philosophy have torn down the Ivory Tower—the majesty of academia—by reducing man to nothing but an ape, irrational, selfish, infinitesimal, and purposeless. Whereas the ancient humanists gloried in the idea of man, today the idea of humanism is practically extinct (at least, within academic philosophy). However, the Christian philosopher can rebuild the Ivory Tower by simply playing history in reverse and using old arguments that still have legitimacy. The key to doing this effectively is to choose secular philosophers who are esteemed by the Academy, locate their defining ideas, and work your way back to orthodoxy.
Here is an example:
1. Let’s say your professor is a modernist who idolizes classic skepticism, in Hume, for example. And let’s say he is teaching Humean apologetics for why miracles do not exist—largely based on his prior proofs that natural laws do not exist. You don’t want to argue against Hume (or your professor) yourself. You want to use the authority of the Academy. There are several ways to do this, but all of them require finding out who, within the philosophical canon, disagreed with Hume. There will be some philosophers before him, and some after, who did. Most likely, the person just before him—who the professor might say logically led to Hume—is the best person to examine because he will have some arguments that imply Humeanism but also some arguments that kept him from believing as Hume himself did. Start the Reconstruction process by researching backwards.
In this case, the person normally taught before Hume is Locke. Sometimes professors teach Malebranche or Leibniz just before Hume, but the logical precursor in most textbooks is Locke. This is a score for you because Locke was a Puritan as well as a philosopher. Many of his ideas were sound and came directly from his Christian worldview. While your professor will paint a completely secular portrait of Locke, and even use his idea of tabula rasa (no innate ideas) against metaphysics, you will find out that that is misinterpretation. Reading Locke’s original works for yourself, such as The Reasonableness of Christianity or Politics and Education, will show you that Locke believed in original sin, total depravity, redemption, and other a priori concepts that oriented man’s personality as well as his place in history. His tabula rasa theory was confined to the development of human experience—a person’s ability to change over time (i.e. backslide, sanctify) and a person’s need for education (i.e. because he comes out in need of knowledge and moral training). He also applied it to human sociology—which is why a king was born no “better” than a slave, and why individual citizens deserved the privilege of liberty or self-rule. The point here is not to wax poetic about Locke, but to reeducate yourself about Hume’s precursor (who was presented inaccurately), and look for anti-Humeanism in his work. Find out why Locke was an empiricist but still believed in Natural Law.
Also look earlier in history, for people like Ockham who reasoned very similarly to Hume but came out with a very different conclusion. Search for Aristotle’s concept of causality, and why he chose to reason deductively about politics and laws of nature, instead of empirically (as he did on many other occasions). But don’t forget to search for succeeding philosophers who also might help you. In this case, Kant, who is usually taught after Hume, has very helpful arguments against Humeanism (and also was a Christian, who believed in mystical experiences). Less benignly, logical positivists such as Comte demanded that lawfulness exist. And many German-influenced philosophers like Nietzsche, Freud, Darwin, and Marx were determinists of other sorts: not only believing in natural law but historical, cultural, individual, or economic “laws.” These types of thinkers, whom you don’t want to endorse, can be used like “icing on the cake” examples after you have already dismantled Humean skepticism with your other thinkers like Locke, Okham, and Kant (who were all Christians and more reasonable). The force of your argument will come from cogently unraveling the positions closest in scope to Hume, and then adding some further detractors as if the first weren’t enough. You could even add in some practical apologetics if you can do it briefly and without religious reference. In this case, you could talk about Einstein and the Manhattan Project post-Hume basically confirming both the theoretical and practical reliability of natural law. This will “cover your bases” depending on who or what your professor esteems as authoritative.
What if you don’t know about these other thinkers? How do you get this kind of information? Christian apologetics books can be good sources of information, especially if you know the particular thinker and school of thought you are trying to debunk… such as Hume and skepticism. Definitely check out websites like LeaderU.com and First Things. First you have to be confident, though, that the answers exist—that the position is bad and needs debunking. You should see that the Bible says miracles happen, so any philosophy which rules them out, is wrong. Also get a list of the Western Canon, and briefly research the people before and after to see if they hold clues, as mentioned. Research other names that come up in the process as possible clues… play detective! In the history of Western philosophy, it is almost certain that either the ancients or the medieval philosophers will have the answers to the modern questions. The ancients will have secular apologetics and the medieval philosophers will have theological ones. But acquaint yourself with a brief history of both so you have an arsenal… the hardest work has probably already been done for you!
You also don’t want to use theological arguments, or catchy things you find in the Christian bookstore because these are largely rationalistic, metaphysical, and deductive. You want to fight fire with fire, using empirical or skeptical arguments—using Hume against himself if possible.