I think the poster acknowledges that the number 20 is somewhat ad hoc and handwavy, for example they go on to do the calculations later in their post assuming fish suffering is 100 times less than human suffering. So they have given the number a factor 5 uncertainty.
Although, when I was reading the post, I saw that as more a rhetorical “trap” than a real point. As soon as the poster says “fish suffering is 20 times less important than human suffering” it invites everyone to focus on the number 20, and start trying to work out if a ratio of 100 or 1,000 would align better with their own instincts. The trap is that anyone who accepts the real premise: that human suffering and fish suffering are somehow interchangeable up to some exchange rate, is already going to be snared by the argument because even gigantic factors are going to make fish farming work out as a bigger problem than say, gun homicides or traffic accidents.
They don’t give a factor 5 uncertainty. They add a 100x discount on top of the 20x discount — counting fish suffering as 2000x less important than human suffering.
I think the poster acknowledges that the number 20 is somewhat ad hoc and handwavy, for example they go on to do the calculations later in their post assuming fish suffering is 100 times less than human suffering. So they have given the number a factor 5 uncertainty.
Although, when I was reading the post, I saw that as more a rhetorical “trap” than a real point. As soon as the poster says “fish suffering is 20 times less important than human suffering” it invites everyone to focus on the number 20, and start trying to work out if a ratio of 100 or 1,000 would align better with their own instincts. The trap is that anyone who accepts the real premise: that human suffering and fish suffering are somehow interchangeable up to some exchange rate, is already going to be snared by the argument because even gigantic factors are going to make fish farming work out as a bigger problem than say, gun homicides or traffic accidents.
They don’t give a factor 5 uncertainty. They add a 100x discount on top of the 20x discount — counting fish suffering as 2000x less important than human suffering.