I agree that there is no way to know, that wasn't my argument. I was merely insinuating that there is no way to argue for the certainty that they aren't.
Richard O'Barry (the first to capture and train dolphins that were featured in Flipper) maintains to this day that Kathy (one of the dolphins) died in his arm in a form of suicide. This being a reference to the fact that unlike Humans, every breath a dolphin takes is a conscience act, and he empathizes that the last time she laid in his arms and let out her final breath, it was a sign of her tiredness of suffering.
What this means to you and I is besides the point, because it is his unique interaction and experience that gives light to the very possibility that something exists beyond our grasp and righteous pomposity
On your other note,
Prot: Every being in the universe knows right from wrong, Mark.