The question is always thrown at me in the most random moments—in the middle of a biology lab, during a tennis team pasta party, or even at a Yale campus interview. And each time, I wonder how to answer it. Throughout most of high school, I gave people an answer that was easy to grasp: for the environment. Not many people bother to argue with hard numbers—who would dispute the amount of carbon dioxide released into the air per pound of meat, the inefficiency of producing a given weight of beef as opposed to potatoes, deforestation per half-pound hamburger? But I always knew that the reason for my vegetarianism was far more complex than just being purely environmental.

A few months ago, my cell phone buzzed late at night, signaling a text message. I was awake reading a book, and fumbled around before flipping my phone open. "So," it read, "I'm vegetarian now…"

The sender of the message was a close friend of mine who had ribbed me for my own vegetarianism for almost as long as I'd known him. He often joked about starting a Meat Club in response to my Vegetarian Club at the high school, casually dropping references to my alleged "moral superiority complex" or for his own love of meat or Epic Meal Time. Although these responses were probably not meant to be serious, I mentally grouped them with the self-imposed immaturity that I usually saw regarding vegetarianism. His message should have surprised me. However, even as I was reading it, I was aware that I felt strangely unaffected about his decision, like I had subconsciously known it all along. But why?

As two students interested in learning more about philosophy, my friend and I had been exchanging readings and thoughts about philosophers and their ideas for some months. I highly valued that I knew someone willing to discuss moral and ethical issues clearly and openly, but still never broached the topic of vegetarianism.

Peter Singer did. On a podcast called Philosophy Bites, my friend heard Singer's argument against speciesism and decided to investigate more for himself. The simplest ethical case made the most sense to him—eating meat is morally wrong because it causes unnecessary suffering.

I was shocked. Not at my friend's decision specifically—I had come to respect his openness about views on controversial topics and thought his choice fit his thoughtful personality. But still, I would have never expected a moral case for vegetarianism to resonate within most people I knew, especially not those my own age (17). Had I underestimated people's capacity to listen and talk about the ethics of choices as personal as their diets? In an effort to "reach" more people, I had stuck to clear-cut arguments about health, climate change, and pollution. But by catering to the preconceived notions of my peers and pointing out the problems meat-eating causes and not the problems with meat-eating, I may have been adding to the very culture of willing ignorance that I despise.

Today, I look forward to people asking me why I am vegetarian. And this time, I can give them the whole answer.