[teddyh]

The killing and eating of animals are not acts which belong to the category of acts needing justification. Stealing and murdering other people affects human society, so those require justification by the justice system. But many acts are not part of the human society, in that the acts don’t affect it. For example, if I sit backwards on a chair, that not a threat to human society, so it does not need justification. Some people like to imagine that such unconventional acts, which they deem “transgressions”, are somehow eroding society, and would like them to be abolished. The current trend in free societies is, however, to be more liberal in what they allow.

[Azek]

Kicking my dog would also not affect human society, does that mean I can kick my dog without justification? For fun?

My point here to be more clear is that we simply don't need to consume animals, and that the taste pleasure of eating them doesn't justify their death. Humans are animals too, and the success of our species doesn't require intense suffering of another.

[teddyh]

> Kicking my dog would also not affect human society,

But it would. At least we have, as a society, decided that it would. But this is rather flexible, since in older times, as well as in some cultures, wanton animal cruelty is accepted. I guess that the argument for prohibiting cruelty to animals is that it is good to prohibit behavior which we believe to be detrimental to the person doing it. I.e. it’s not prohibited to protect the dog, it’s prohibited to protect you from becoming a cruel bastard and turning around and being toxic in human society. Whether this actually is a valid argument is, of course, subjective and debatable, which is why cultures differ on this point.