What is your definition of 'individual'? A group can have values just as easily as an individual, even if your attempts to quantify that value are necessarily fuzzier.
Nothing useful is ever true by definition. Society has values because social contexts promote preferred actions. You start thinking about this by trying to define morality in useful manner:
A morality is an algorithm that models counterfactuals and assigns values to them.
(I.e., it _evaluates_ possible states of reality and prefers some to others.)
Thus group morality is an aggregate of individual moralities, though it isn't necessarily a linear aggregate, nor is it necessarily known or (even knowable) by any individual. Either way, all you need is a hypothetical, because any reliable _reasoning_ you do about group morality is going to try to optimize in terms of flexibility: if there is an ideal outcome for a group, then every action should be taken to ensure such an outcome is not eliminated from potential futures.
This implies a lot about group morality. It means information processing is valuable. (And hence, some vague notion of intelligence or creativity is valuable.) Generally speaking, a group is a decision-making entity, and it must value its own ability to make decisions and moral evaluations as a consequence.
What is valuable to a society is not some specific state, but the ability to rapidly converge to better states as more information is obtained. Social stability, situational responsiveness, rapid dissemination of facts, efficiency, correctness, etc.. Every society values these things, even if they cannot be used to determine specific behavior for individuals. Arrows theorem says that there is no way for a preferred state to be knowable to an individual.
It helps to think of a group as a network of brains in the same way that a brain is a network of neurons. It's a different kind of brain, but it still does all the brain stuff as a simple consequence of the fact that it is a strict superset of brains. Naturally, one brain cannot contain the information of 10,000 brains. (Thus, Arrow's Impossibility Theorem.) But one group can. We cannot know it, but we can presume such a state exists and optimize on flexibility, not state.