Idiot Stampede.
For example,
> Why the hell shouldn't the Japanese eat whales, we eat pigs, sheep, cows,
> goats, ducks, pheasents, and well lots of other animals.
Whales are rare, wild animals with fidgety reproductive habits who go about their business... until and unless a whaling ship impales them with a hundred pounds of steel harpoon or so, inflicting traumatic injuries which lead to eventual death from blood loss, organ failure, drowning or - if they're reeled onto the processing ship quick enough - vivisection... a process which takes anything from minutes to hours.
Pigs, sheep, cows, goats, ducks and pheasants are farm animals with fecund reproductive habits, cultivated by human beings for the express purpose of becoming food. They are fed, kept (relatively) healthy and warm, and eventually despatched by methods designed to be (relatively) quick.
The Japanese like to use the non sequitur about Australians beong hypocrites about whaling because they eat kangaroo meat (and emu; the other animal on the only fully edible national coat of arms on Earth). Funny how that narrative stops short of mentioning that the kangaroo meat on sale in Australia comes from *farmed* 'roos (too high a risk of parasites in meat from wild 'roos, apparently), or that kangaroos can reproduce at a rate of four to six young per female per year.
If people can't see the difference between the protracted kiling of rare wild animals and the (relatively) clinical killing of abundant farmed animals, then they're too pigshit-stupid for me to really try to change their mind...
> We keep dairy cows in a perpetualy pregnent state for milk and cheese.
Well, there you go... see why people turn vego?