Final answer:
In contractualism, all morally wrong actions are those that individuals would not agree to in a rational, hypothetical contract, as they would harm society or individuals in an unacceptable manner. thus an action is morally wrong if it fails a test of mutual agreement by all affected parties.
Step-by-step explanation:
According to contractualism, what unites all morally wrong actions as wrong is that these are actions which people would not agree to in a rational contract, as they would harm society or individuals in ways that are not acceptable to a community's moral framework. Contractualism, which is a form of deontological moral theory, asserts that moral truths are based on the principles that no rational person would reasonably reject as a basis for informed, uncoerced general agreement. Thus, an action is wrong if it is one that would not pass this test of agreement by all affected parties, should they be placed in a hypothetical original position of equality.
The concept heavily relies on the idea of mutual agreement and fairness, based on rationality and respect for persons. This is in contrast to consequentialist or utilitarian thought which holds that the morality of an action is solely determined by the positive or negative consequences it produces, with no intrinsic concern for fairness or agreement between individuals.