The question as to what evidence there can be is a grammatical one. It concerns the sorts of actions and propositions which would verify the statement.
Suppose you say "Good is a quality of human actions and events".
Given perceptions and actions, animals have the capacity to develop memories and prior intentions, as well as beliefs and desires and other forms of intentionality, such as expectation and fear, anger and aggression.
Many species of animals have perceptions, perform actions and are capable of acquiring beliefs, desires and intentions, though they have no language.
Imagine that there was a species like us, having a full range of prelinguistic conscious experiences, voluntary actions, and prelinguistic thought processes, but no language.
Features Common to Prelinguistic Intentionality and Language I have already said that the hominids have conscious perceptions and intentional actions together with conscious thought processes, all of these in a prelinguistic form.
Now, once that deontology is collectively created by these intentional actions, then it is very easy, indeed practically inevitable that it should be extended to social reality generally.
The answer derives in part from the fact that speaking is a voluntary activity, perhaps the most paradigmatic form of the human freedom of the will, and where free voluntary actions are concerned, people perform these actions in their own free voluntary ways.
The existence in monkeys of mirror-neurons (Rizolatti, Fadiga, Gallese,
My second maxim was to be as firm and resolute in my actions as I was able, and not to adhere less steadfastly to the most doubtful opinions, when once adopted, than if they had been highly certain; imitating in this the example of travelers who, when they have lost their way in a forest, ought not to wander from side to side, far less remain in one place, but proceed constantly towards the same side in as straight a line as possible, without changing their direction for slight reasons, although perhaps it might be chance alone which at first determined the selection; for in this way, if they do not exactly reach the point they desire, they will come at least in the end to some place that will probably be preferable to the middle of a forest.