Rule 14: Take religion seriously
Ok, this one might be controversial. But it has been much on my mind recently since I am writing episodes on medieval philosophy, where religion is woven into pretty much every text I am looking through. As I write the scripts I am thinking a lot about how to present the material in a way that will be interesting and seem relevant to listeners who don't care much about religion, without misrepresenting the material or for that matter letting down listeners who do have an interest in the religious side of things. At any rate, it seems to me important to remember that the vast majority of figures available for us to study in the history of philosophy have been religious believers. This goes not only for the obvious cases like the medieval Latin Christians but also for pagan thinkers of antiquity; we can assume that nearly all of the people I covered in episodes 1-100 (i.e. before arriving at ancient Christianity) were practicing pagans, and that includes household names like Socrates, Plato and Aristotle. They may have had culturally unusual interpretations of the religion of their day but they were in some sense themselves religious (by which I mean that they believed in divine entities and presumably engaged in cultic practices) and more importantly for us, they felt the need to engage with religion in their works. So religious issues are (to differing degrees, but almost always to some degree) woven into the very fabric of the philosophical works we are reading from antiquity, and this also goes of course for the medieval period in various cultures, and for early modernity. I guess that it also applies to philosophy from Asian cultures; stay tuned for future episodes touching on that issue in classical India! Nowadays most professional philosophers in Europe and the US seem to be atheists, as far as I can tell, but that is a very recent development, even if one can point to occasional atheists in earlier periods (Hume is a favorite example).
What does this mean for the historian? In the first place that we need to learn about religious context just like the other aspects of historical context. No surprise there. But it also means something more challenging, which is that one needs to take an objective and open-minded attitude towards the philosophers' religious beliefs. Insofar as we are historians of philosophy, our goal should not be to take inspiration for our own religious faith if we have it, or to find the mistakes made by great religious authorities for the sake of reinforcing our own lack of faith if we don't have it. Rather it should be to understand how the religious views interacted with and influenced the philosophical views - to take a very nice example that's coming up a lot in the podcast these days, how Augustinian ideas about grace affected views on free will. Actually I would go further and say that we shouldn't even worry which aspects of a thinker's worldview are "religious" as opposed to "philosophical." Much of the time this dividing line is going to be blurry or even non-existent, and there is no reason to get anxious about this. I know from comments I've seen here on the website that some listeners think that philosophy is antithetical to religion; whatever merit that may have as a philosophical position nowadays, it is not a good place to start from in doing history of philosophy.
This is not to say, of course, that one's own beliefs remain irrelevant. If you are an atheist you had better be ready to say what is wrong with Anselm's ontological argument for the existence of God, once you have done your best to understand it! It's just that, as I've argued before in this series of rules, the first and very challenging step is to understand the texts you are reading, and taking religion seriously is part of that.
"Actually I would go further
"Actually I would go further and say that we shouldn't even worry which aspects of a thinker's worldview are "religious" as opposed to "philosophical." Much of the time this dividing line is going to be blurry or even non-existent, and there is no reason to get anxious about this."
I think part of what makes letting go of this worry difficult for many people is that the idea of a clear dividing line between philosophy and religion is often tied up with the idea that philosophy was invented in ancient Greece. Often when making this claim, people have the idea that they can dismiss earlier thought as religious mythology... if they admit that the line between religious thought and philosophical thought is not so clear, such dismissal becomes groundless.