I became vegetarian many years ago for precisely this reason. Ordinarily I don't get preachy about it, and tell people that it's just an individual choice of mine. But in truth, the concept of eating meat really does bother me, and I think it bothers a lot of other people.
Other carnivorous animals are rarely aware of the fact that they are using other sentient beings for food (although sometimes they do demonstrate an awareness of this), but we can't help but be aware of it. We justify it with a values system which says that it is morally permissible to eat creatures that aren't as smart or are otherwise just different from us. But that's a tenuous sort of morality, and I honestly think that it gnaws at us more than we usually admit.
Think about how aliens are typically portrayed in science fiction films. They've crossed unimaginable light-years to come to earth, and are immensely smarter than us. But nine times out of ten, once they get here, they've got nothing better to do than kill and more often than not eat us. Same goes for superior machine consciousness: in our mythologies, it almost always wants to kill and/or consume us. Why?
I think it's a reflection of our own insecurities: if there's any species out there that's truly smarter than us, we'd better hope that it doesn't share our value system -- because if it does, then it will see us as entirely legitimate to farm and eat.
So I choose to do unto other species as I'd like other species to do unto me. But of course that's just my personal choice.
If you use anything made with/from animal labor or products, you are practicing the same form of morality, you've just changed what's acceptable from "murdering" to "enslaving", "robbing", etc.
It is also no more tenuous than arbitrarily drawing the line at bugs or bacteria. Thousands of innocent insects had to die to bring us a banana (--death from pesticides, from mechanical crushing during harvest, from geting squashed on the windscreen of the delivery trucks).
It's not arbitrary to draw the line there, although it may be hard to argue for making it a line.
I eat meat, but I do feel it would be more ethically right to avoid it. In the same manner, it would probably be more ethically right to not buy/drive a car, not use cell phones (conflict minerals), give more to charity etc. (So where do you draw the line at how much of your own money you get to keep for yourself?) Something can be ethically bad even if we do not draw a line in the sand (or, even if we do not as a society deprive someone of the freedom to do those bad things).
If I were a vegetarian, and drew the line at eggs or whatever, I would be drawing the line because a line would make it possible and practical to live as a vegetarian. (Similarly, the law has to draw a line somewhere.) Nature doesn't draw the sharp lines that our human languages do, but that doesn't mean we can't rank actions in terms of more or less ethical, it just means it's hard work.
A lot of ethicists draw the line at either sentience (not sapience) or the ability to suffer, usually defined as the presence of a central nervous system. Bacteria fails to pass these tests.
I've always heard "sentience" defined, especially in contrast to sapience, as the ability to simply perceive one's environment. You may be using it under a broader sense, though, because bacteria can undoubtedly sense and react to their environments, and even communicate information to other nearby bacteria. It's a pretty fascinating area.
Here's a summary of a paper in Nature about Bacterial perception:
Better still is the communication, one example is quorum sensing. Bacteria sometimes take little polls before acting, like little mobs trying to rile each other up:
To the bigger point, putting an ethical line in here somewhere always struck me as a bit of a sorites paradox, the endpoints are fairly easy (don't torture humans, don't worry about bacteria), but there's no obvious line in the middle where you couldn't make an argument to include or exclude just one more species, especially when you confront the staggering biodiversity out there, and start to see everything as more of a spectrum and less discrete.
I avoid smarter animals, like pigs, squid, and octopi (dogs, cats, monkeys, or ravens if they ever came up). Cows and chickens are fair game. This is basically arbitrary, but I don't believe it's any more or less tenuous than anyone else's system, we're all making a call with limited information. (As Thomas Nagel put it, no amount of human thinking reveals what it is like to live as a bat.)
Sure, those are traits we use to distinguish different rights among sentient (but not sapient) animals--but it's all rather arbitrary.
How do we define "suffering"? Is it the same emotional experiences we call "fear" and "sadness", i.e., the ability to have the concept "I am afraid/sad"? That means the animal needs to at least have a primitive form of understanding and introspection to qualify (e.g., great apes, chimps, bonobos).
If we go to the other extreme, we must admit we don't have a reliable method for communicating with animals (famous "dog whisperers" aside). We can only infer "suffering" is taking place when the animal reacts negatively to a negative external stimulus. But bacteria respond negatively to a negative external stimulus as well. Sure, there's mind-bogglingly more complexity in a mammalian brain than a bacterium, but if we reduce "suffering" to the observation of a negative reaction to a negative external stimulus, we must say even single cell organisms are "suffering."
Hopefully the aliens will forgive us if we seem barbaric ;)
Part of my experience is a recent trip to India to see some historic sites. While there, it was just easier to eat at vegetarian restaurants, and it was remarkable how much healthier I felt. It will certainly involve some work because I grew up in the West and we simply don't have this sort of culture ingrained, but all great things take some work.
I guess what I found out is that we have a choice: we don't have to eat meat and we can still maintain and even improve our health. That was the straw that broke the camel's back, so to speak...
Other carnivorous animals are rarely aware of the fact that they are using other sentient beings for food (although sometimes they do demonstrate an awareness of this), but we can't help but be aware of it. We justify it with a values system which says that it is morally permissible to eat creatures that aren't as smart or are otherwise just different from us. But that's a tenuous sort of morality, and I honestly think that it gnaws at us more than we usually admit.
Think about how aliens are typically portrayed in science fiction films. They've crossed unimaginable light-years to come to earth, and are immensely smarter than us. But nine times out of ten, once they get here, they've got nothing better to do than kill and more often than not eat us. Same goes for superior machine consciousness: in our mythologies, it almost always wants to kill and/or consume us. Why?
I think it's a reflection of our own insecurities: if there's any species out there that's truly smarter than us, we'd better hope that it doesn't share our value system -- because if it does, then it will see us as entirely legitimate to farm and eat.
So I choose to do unto other species as I'd like other species to do unto me. But of course that's just my personal choice.