Mackie

"But it is not the mere occurrence of disagreements that tells against the objectivity of values. Disagreements on questions in history or biology or cosmology does not show that there are no objective issues in these fields for investigators to disagree about. But such scientific disagreement results from speculative inferences or explanatory hypotheses based on inadequate evidence, and it is hardly plausible to interpret moral disagreement in the same way. Disagreement about moral codes seems …

…rights-based ethical approaches seems common, there may be some disadvantage to treating them as exactly equivalent. Nagel and others argue that deontological constraints are only violated by intentional actions. Thus, a duty not to harm others would not be violated if one causes harm accidentally or unintentionally. But if the duty not to cause harm corresponds to a right not to be harmed, the right would be violated regardless of the intent of the violator.