Two weeks of two English classes at the graduate level, and I haven't come across another philosophy minor. English students are naturally curious, and most undergrad programs didn't offer enough English to round out our schedules. So we played the field. I chose to flirt with philosophy (after flirting with history, who turned out to be a bore) and then fell head over heels for knowledge. I may have a curiously intense love of "the love of knowledge," but if you are an English student who doesn't have delusions of being a full-time poet, I can't recommend philosophy enough as your second-study.
I can think of quite a few reasons to study philosophy, but I'll distill that down to three big reasons philosophy will help your English. Philosophy trains your brain for discourse; philosophy helps you write like a scholar; philosophy prepares you for theory and criticism. For me this all boils down to being good at what I like to do. If that's not enough incentive in this economy, these three things also boil down to being employable and publishable.
Some of you might not like the third reason for studying philosophy, so I'll start there. You might hate theory, but you can't get out of being a critic. In my current lit crit class, a first for some of the students in there, the professor reminds us, "You're all critics, whether you like it or not." And when you turn your critical eye toward literature, art, or culture, you need to understand the theoretical background of the type of criticism you are applying. For an understanding of what certain theoretical positions do or don't take into consideration, whether they look at a text up close or from a distance or from someone else's point of view, whether they have anything to do with the real world or are content to stay in the abstract, can keep your thinking clear, keep your arguments unmuddled, and make your job of critiquing much easier. A background in philosophy helps keep you focused in this way, to think things through and write on them with cogency, and most of all to have the intellectual confidence to approach theory in the first place.
If you still don't think theory is important consider philosophy alone -- the first critics were philosophers! On day one of your first lit crit class you'll have to recall Plato's forms and Aristotle's unities. Now, criticism fell to the writers themselves for centuries, though they still drew on early philosophical ideas about art. But then, in the twentieth century, we came full circle with the philosophers snatching up the literature once again (only reading them you might not know they're talking about literature at all) and analyzing the heck out of it, and so came and went "High Theory." Theory might be mostly passe, but like Plato it hasn't been forgotten. If you ignore theory, you'll be writing the criticism of a hundred years ago. Now personally I'd think that was pretty neat, but you'd have to be a damn good critic and writer to pull it off! So if you can't pull it off you'll be writing the criticism of your freshman year: bullshit. Even if you know that theory is not for you (and you may change your mind!), you can't escape theory's importance to criticism, and like I already said (and your professors will reiterate) you can't escape being a critic.
When we introduced ourselves in class, one girl said she would not be a critic, but simply read books forever. I confessed that I probably don't read enough books because I spend too much time writing about them (and everything else). The professor assured me that I would make more money than the book readers. I didn't mean for my confession to come off as a brag, but the professor's comment shows what kind of work you need to be willing to do if you're going to bother with advanced degrees in English. I credit philosophy with giving me the mental patience to ruminate on things in this way -- and to be analytical, not simply interpretive.
I also credit philosophy with giving me the patience and diligence to write more clearly, more cogently, and with more authority than a bachelor's degree in English demands. Sure we had to write a lot, but we weren't graded very stringently or very consistently. A few decent poems and a few insightful sentences per paper can get you a bachelor's degree in English. Since most programs don't require that many classes in the discipline, it's up to you to determine how the rest of your mind gets trained. Languages are helpful, but a minor in Spanish does not give you an entire framework on which to hang your knowledge the way philosophy can. History helps give the literature one kind of context, but for many of us that particular context turns out to be somewhat unimportant. Only in philosophy was I consistently required to produce top notch work and do top notch thinking, only in philosophy was I expected to provide an excellent argument for any claim I made, and only in philosophy did the red marks on my papers provide real assistance in becoming a better writer. There is no bullshitting in philosophy, not past your introductory course anyway. It is a good idea to purge that stuff -- muddy writing, unfinished arguments, irrelevant notions that work their way into your thought-stream, &c. We are English majors. Shouldn't we be the best writers? Philosophy majors score higher than us on the writing and verbal sections of the GRE. English majors/philosophy minors, let's teach them a lesson!
The first reason I listed for studying philosophy is that it trains your brain for discourse. Discussion is a spirited part of upper level philosophy courses (try to take seminars or special topics!) and we know, not just because Socrates told us, that dialogue is how we come by knowledge. Philosophical debate is excellent training for the kind of debate you'll encounter as a graduate student in English, or even in your upper level English courses as an undergrad. You will not only fare better at discussions, and weather disagreements better, but you will have seen how you can learn about something by talking about it with your peers (uh, I think I'm supposed to call them colleagues now). Too often in the English classroom we set our opinions in stone before we let anyone else's ideas do any work upon us. Discussions don't go anywhere. But why get behind an opinion, or even an interpretation if you don't have an argument? Philosophy gives you a mind that generates an argument, adapts the argument when you receive new information or ideas, and builds upon the argument dialectically even when it seems to have been canceled out. Read your Hegel!
Besides the discourse you'll encounter in class, you'll also be entering into some of the discourses that are going on in English. "Join the conversation," they tell you in undergrad, when you first learn to incorporate the criticism of the scholars into your silly papers. Philosophy is indispensible in joining the conversation, for the reasons mentioned above. And this comes back to the criticism --if you want to work, you have to be a critic, and if you want to be a critic, you have to join the conversation. Or start a really good one, with a really well reasoned argument behind it.
You can take my word for all these things, or you can ask a professor who teaches lit crit and theory or who uses criticism along with the texts in his or her courses. There are those who don't do either, and there are those who will tell you they hate theory. They may be creative writers, or they may be dedicated teachers. But the ones who teach theory and criticism, and even some of those who claim to hate theory, will remind you of the importance of both for your chances at grad school, and for your chances at a career in English. In today's competitive academy, shouldn't we try to be good at all the things English-people are supposed to be good at, including criticism, teaching, and writing?
If you think you'll read books forever, lying in the sand, or if you think you'll publish all your collected poems, or if you plan to be a master Shakespearean, maybe all of this will fall on deaf ears (blind eyes?). But if you have any interest in doing the work of the literary critic, which is what all of us are if we've declared that major in English, I highly recommend checking out some philosophy classes or talking to your adviser about how a philosophy minor fits in with your studies. The first step of course is getting some theory into your undergrad plans, so that all that criticism you read (and do) has some kind of meat to it -- and philosophy classes make those theory classes so much easier to deal with! The learning curve will be steep if your first encounter with both happens on your first day as a graduate student.
The only reason not to study philosophy? As far as I know, no one thinks it's cool.