On the micro-level, you focus on one person deciding between an all-plant diet and a part-animal diet. The all-plant diet will nourish them, but they find the part-animal diet tastier. Can they justify the harm they impose on animals in terms of the taste-delta, so to speak? No, it seems clear they cannot. Next issue: will all humans ever recognize this fact and switch over to an all-plant diet? The issue seems entirely about self-involvement vs. altruism. Are we good enough to all become vegans? The more optimistic among us say Yes. The less optimistic say No.
But now start on the macro-level, and think about oceans. 71% of earth is covered with ocean, and seafood provides 20% of animal protein, world wide -- 50% in some countries. In a vegan world, the ocean simply stops being used as source of nutrition. Land gets wasted too. Only 10% of the earth's land surface is arable--used to grow for crops. 26% of the land surface is used as grazing land. Most of that grazing land is not convertible to cropland, so if animals weren't being raised on it, it would simply be lost to food production. The total lost to food production: about 79% of the planet's surface.
Now, a vegan earth is also a planet where the cropland is used more efficiently. As it is, a third of cropland is used to feed confined animals (the ones not on grazing land). So the cropland will feed far more people, in a vegan world. Maybe -- I'm not sure -- everyone will still get fed. But by not consuming animals raised on grazing land or living in oceans, a vegan world leaves a great deal of the earth's surface unused for food--the oceans plus all the grazing land that couldn't be used to grow crops. To make up for this, there has to be lots of importing-exporting, and lots of local people stop being self-sufficient food producers.
It seems to me there's got to be some law of biology or economics (er ... what is it?) that says no to this. It just can't be that a species decides that a vast amount of its habitat is off limits, as far as obtaining food is concerned. Now, we don't want to make the mistake of thinking "natural, therefore good," or anything so crude, but there are some aspects to nature that just aren't going to be transcended, no matter what. For example, people will keep having sex and reproducing. And more to the point, they will keep spreading out all over the globe, using every acre of it for food production.
I know what someone's going to say. If we're inevitably going to use every acre for food production, would it be OK to use every acre of Manhattan for food production? May we round up New Yorkers, and turn them into hamburgers? Well, no. And we're not going to eat chunks of the Grand Canyon either. But -- perhaps you still see the point. Manhattan is tiny. We can pass up Manhattan Burgers, but can we really let 79% of the earth be non-food territory?
Things look very different when you switch from the micro-level to the macro-level. On the micro-level, the person who eats meat seems to prioritize their taste-delta over the well-being of animals. Selfish jerk! But now think about humanity collectively, on the macro-level. We use the whole earth for food production, which must mean we eat other animals. It's not a matter of selfish pursuit of pleasure, but of the basic laws of biology and economics. The pleasure people get from eating meat isn't an ultimate end, looking at in the grand scheme of things, but actually nature's way of getting them to obey those basic laws.
A vegan world violates the very most basic laws of biology and economics, whereas an omnivorous world does not. So--to hell with worrying about the treatment of "food" animals? No, no, no. It's just a starting point to recognize that we're not heading for a vegan world. There's a lot that's wrong with our omnivorous world. We use every bit of the earth for food (fine) but over-use it (not fine). We use resources inefficiently. That's particularly so with respect to the confined animal sector. Confined animals are fed through the inefficient use of valuable cropland. That makes no economic sense. These operations also pollute air, water, and land. There are also issues about the over-use of grazing land--too many animals means too much methane--a greenhouse gas. Finally, and very importantly, there are issues about the horrifying cruelty of these operations.
If you think we're heading for a vegan world, you'll think it's trivial, and even retrograde, to bring about small reforms, like two on the horizon right now:
Federal legislation introduced - bigger cages for laying hens
McDonalds ending use of gestational crates
But we're not. So we should be for these reforms and support the organizations working for them. I keep hearing Wayne Pacelle of HSUS on the radio, and think he's the cat's pajamas. If you're abolitionist Gary Francione, you hate the guy, because he's making life incrementally better for animals, while leading everyone a little further away from a vegan world. But I think we're not heading to a vegan world, period. It's not a question of human selfishness, but a simple matter of biology and economics. We just can't let that much of the earth's surface be labelled "not for food."