C4 Diesel

I think part of the issue here (a similar issue that I find in many debates) is that morality is subjective. Being subjective, it is subject to taking on a sort of "collective truth". Killing people is immoral because a significant majority of society has deemed it to be so, and society has upheld that belief for a significant amount of time, giving the subjective moral issue a seemingly objective component of "truth". It can not be stated in a similarly quasi-objective manner that eating meat is immoral, because that is not the accepted viewpoint of society. Eating meat is fine and perfectly moral because we say it is, and have had that consistent viewpoint for a very, very long time with only a few, minor exceptions throughout history.

Following a similar logical pathway, we see that inflicting damage to other animals is seen to be quasi-objectively "immoral" (although this has generally only been applied to vertebrates - very few cringe when you kill a snail). Now we have two "truths" that are in direct conflict. Killing and eating animals is okay, but harming animals is not okay. Being that killing animals for food has been moral longer than harming animals has been immoral (by societal standards), eating animals wins the moral battle and remains an acceptable practice.

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C4 to your door, no beef no more...