I know someone who only listens to the music of Bob Dylan. Now, I respect Dylan's songwriting immensely and I play a number of his songs, but I don't think you can call someone who only listens to Bob Dylan a lover of music. That requires what jazz musicians call big ears: an appreciation for a wide variety of musical styles, composers, and performers.
The situation is similar with philosophy as a way of life. It's true that there are people who live philosophically but who limit themselves to one school or system of thought, such as the Stoic philosopher and Roman emperor Marcus Aurelius (whose Meditations I'm studying these days). Yet the more I read, the more I realize that there is so much to learn from different traditions and thinkers (most recently for me the Stoics and Indian philosophy - an entire universe of thought that I've just started to explore). Because life is short, I tend to focus where I can learn most deeply; learning, in turn, is related to motivation, and motivation is related to affinity. Thus I'll probably never spend all that much time immersing myself in, say, Sartre or Kierkegaard or Kant or Augustine or Plotinus - when it comes to ethics they're just too far from my core interest in finding and living a positive, secular philosophy of eudaimonia.
Matters are similar with respect to political philosophy. Here I don't have nearly as much as energy as I do for ethics, because so much is outside my span of control. However, when I do find some energy I try to open myself up to schools of thought that share the goal of human liberation. Thus recently I found myself learning more about mutualism and market anarchism (more about that in a future post).
The political realm is even more rife with systems and ideologies than ethics is, and many people read only authors they basically agree with. Yet political - or, better, social - life is also a matter of ethics. Thoreau saw this clearly, for he tried to live a life of principle inside himself, in his family, with his friends, and within his community. How you work, what you produce, what you buy, where you live, the people you help, the organizations you support - these too are matters of practical philosophy. Reducing social or political life to mere ideology is unnecessarily constraining, because it prevents you from learning about alternative viewpoints that can help you "to solve some of the problems of life, not only theoretically, but practically" (as Thoreau put it in "Economy", the first chapter of Walden).
Unfortunately, the siren song of ideology is strong; to resist it, you must not stop up your ears as Odysseus did but instead open them up to sources of wisdom you wouldn't otherwise consider. I know that I need to almost force myself to do so. Thankfully, the benefits much outweigh the costs...
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