Can’t mentally decline if you were never sound of mind in the first place!

Ehh that’s a very cynical and kinda misleading take of how it works. This may be generally true in the house of representatives but still 12% of the seats don’t end up funnelled to the two major parties. In the senate a quarter of senators aren’t affiliated with either major party and at the moment it requires Labor to collaborate to pass bills, so although we do have two major parties we are nowhere near being a two-party system.

Nobody is saying that fish are moral agents that can empathise with other beings. That doesn’t man that they’re not moral subjects; the ability to understand that one is causing harm is not a prerequisite for the ability to suffer oneself. I think everyone knows this intuitively, but it does feel good to have our less moral habits be justified by memes that we would otherwise find to be illogical.