Abstract: Ethitropism is 'cooperate with cooperators.'
(Ref: long ver.)
Ethitropism is my name for someone who wants to do good and avoid evil.
Everyone has preferences. Some of these preferences can be universalized: they are the correct target for Kant's imperative, instead of rules per se. The universalizable preferences are moral values. It turns out the moral values are identical to property rights, using the definition 'reasonable expectation of control.'
Moral nihilism is true: acts can be neither evil nor good, justifiable nor unjustifiable. However, prudence & property rights imply the classic moral rules: no murder, no fraud, no theft, self-defence. If someone is an ethitrope, willing to respect your values, it is prudent to respect theirs in return. If someone is anethitropic, it is prudent to neutralize them in any convenient way. Hence, the ethitrope should respect the property rights of anyone who will respect their property rights, and only such people. The ethitrope should cooperate with cooperators.
Justice is classically defined as a society that rewards good and punishes evil, as opposed to vice-versa. Since neither good nor evil exist, a just society is one that empowers ethitropes and disempowers anethitropes. An unjust society is imprudent and weakens the society, ultimately killing it, as anethitropism is always a negative-sum game.
Tangent: Anethitropic acts are identical to coercion. This is the only coherent concept anywhere nearby the commoner's definition of coercion. As a result, states are inherently anethitropic and unjust.