I agree with the argument you're making, but not with your colonist example. Dolphins, after all, are animals, not people. "Cultural heritage" argument is in a league of its own when it comes to harming humans.
Yes they are "animals". So are we. Our intelligence is not much superior to theirs (it's arguable that only the lack of opposable thumbs prevents them from getting on the ladder of developing technology — they already use tools), and they experience the full range of emotions as we do.
How would you feel as your entire clan was herded into a box canyon and slaughtered with knives, as you wade through their blood awaiting your knife?
The "Cultural Heritage" argument is indeed nothing more than an utter bulls*hit excuse when it comes to such barbaric practices. By the same token, we could justify punishment of being tarred, feathered, drawn and quartered in the town square.
I'm not sure it will be in our lifetime, but I fully expect that eventually all eating of killed meat (vs cultured/lab-grown meat) will be seen as barbaric as other barbaric middle ages practices, and as slavery.
A claim that it is "preposterous" is itself preposterous and works only if you are ignorant.
Dolphins have language, complex society & culture, self-awareness, use tools, use names for themselves & each other, have higher brain/body-mass ratio vs humans, invent games, act ethically, cooperate across species, and that's just the start of the list when we're only just starting to research the topic.
With all of those components of intelligence (and some features even more advanced vs human capabilities), it should not take much intelligence to see how having opposable thumbs and the ability to write and build on information is a very small step in terms of actual intelligence, BUT that this yields massive visible differences in abilities to change one's environment. (It's still to be seen if this is an actual survival advantage - the Great Filter may still be ahead of us, and be accidental suicide by technology misapplication).
Also, claiming that a single point "invalidates" all other arguments commits a number of fallacies, including Overgeneralization, Non-Sequitor, and Argument from Incredulity...
If you want to feel like it's OK to kill and promote killing of other species for no good reason, it'd be better to just own it than to attempt justifying it with dismissive displays of ignorance.
We do indeed make exceptions for humans. We frequently ignore issues like child marriage. Widespread pederasty was ignored in Afghanistan for respect of their culture.
Even in the “Western” world the lack of statutory rape law in France (just changed this year) was mostly ignored because it was just considered part of French culture.
How would you feel as your entire clan was herded into a box canyon and slaughtered with knives, as you wade through their blood awaiting your knife?
The "Cultural Heritage" argument is indeed nothing more than an utter bulls*hit excuse when it comes to such barbaric practices. By the same token, we could justify punishment of being tarred, feathered, drawn and quartered in the town square.
I'm not sure it will be in our lifetime, but I fully expect that eventually all eating of killed meat (vs cultured/lab-grown meat) will be seen as barbaric as other barbaric middle ages practices, and as slavery.