My experience as someone who was a vegetarian for nearly 5 years and as someone who loves to eat meat now is that it's funny. I was never vegetarian because of the humanitarian or whatever they want to say that it is side of things. I was vegetarian because the girl I was engaged to was and frankly I wanted to be able to eat around her and not have her feel ill about the prospect of kissing me afterwards. Seriously though, more vegetarians and vegans make a stink about how I stopped eating meat and went back to doing so than anyone who eats meat does.

Though this argument is redundant a bit like the plastic bag and recycling argument is: The animal is going to be slaughtered and farmed regardless, therefore is it not more wasteful/cruel to the animal to leave that meat sitting on the store shelf to go off than it is to eat it? I would say yes because if you do that then essentially you say it is ok for the animal to live and die in vain. You're also making a mockery of humans elsewhere in the world who cannot eat and are starving as a result. I would rather eat the meat and know that it had not gone to waste then waste it by leaving it to go off.

By that same measure I argue that it's essentially irrelevant if you take your own shopping bags or use plastic bags from the supermarket, the bags will still be made in as high a volume tomorrow as they were today. Just because you took your hemp/canvas jute bags in to carry your groceries home doesn't mean that will change. The best you can do is take the plastic bags and see that they get recycled. Unless you introduce legal changes on a global scale about the production and use of plastic bags you'll never change the world.