DRes82 said:
Panda was saying that the reason this is not a morally subjective situation is because logically, anything that causes less overall suffering is the ethically correct thing to do.
"Net" suffering is not the same as simply deciding in any given scenario what will be the best short-term result and choosing that outcome. There are long term ramifications one has to consider, in addition to rippling effects that the implication of saying "this is morally correct" have upon society at large.
Let's use the scenario of the dog and I'll skip the details and grant that in this specific instance of pet vs. human the pet's death would cause more short-term suffering than the death of the human. Is it still immoral to save Fido? Yes. A society in which it is socially and morally acceptable to save a dog over a person is going to have a great deal more net suffering than the society where Fido drowns, even if on the micro level the death of Fido is more acutely felt.
Why? Humans have a high capacity for suffering, and the death of a human will generally ripple through dozens, even hundreds of individuals who will all suffer in turn at comprehending the news that they have a friend or family members who drowned. Even if in one specific instance the short-term gain favors saving a dog, it's still not a good idea to set a societal standard where that is acceptable.
To give a different example I heard Sam Harris use, imagine you have four sick patients with no families in the emergency room, and by killing one you could save the other three. Is that a moral thing to do? No, even though the short term suffering arithmetic clearly favors killing one to save three, the long term consequences in living in a society where any minute someone might kill you to harvest your organs leaves a lot to be desired. Short term gain, long term failure.