(A reader posted a comment on a blog entry and it's a point that I've heard raised before. I thank her for bringing it up and giving me the opportunity to give a response to it.)
Comment: The Buddhist people don't believe in killing animals but you should always remember that plants are also living things.
Response: Yes, plants are living beings too. However, they do not have the levels of self awareness nor the nervous system that animals have. And it takes a lot more grass (corn on factory farms) to make a steak than it does to feed a human.
The reality is that all animals in the cycle of rebirth have three choices: 1) eat animals, 2) eat plants, 3) don’t eat.
Our very existence causes suffering to other beings, be the other being an animal or a plant. As vegetarians and vegans—Buddhist or otherwise—we do the best we can given the options we have. We try to cause the least suffering by eating plants and by eating only what we need to in order to stay healthy and by not wasting any food.
Making this choice is not always easy. The new vegetarian/vegan needs to re-educate him- or herself. This includes reading labels on every food item they are considering. New recipes have to be found and some old favorites abandoned. Family members or friends may not agree with the person’s wish to become vegetarian/vegan. Family members or friends may feel uncomfortable, or even threatened. They may keep challenging or arguing with the vegetarian/vegan, about their decision. Eating away from home can be difficult when food choices for vegetarians, not to mention vegans, are limited and sometimes non-existent.
Considering that many vegetarians/vegans encounter all the above obstacles (I had the good fortune to have the support of family and friends so did not run up against every obstacle), I’d say their efforts and commitment are admirable and worthy of support.
People who choose to be vegetarian or vegan are trying to cause the least harm and suffering they can in an imperfect situation.
It's not that they don't know that plants are also living beings. It’s just that option #3 above is not really a good option.