Could've known better

Abstract Could you have taken precautions against a risk you were unaware of? This question lies at the heart of debates in ethics and legal philosophy concerning whether it's justifiable to blame or punish those who cause harm inadvertently or out of ignorance. But the question is crucially ambiguous, depending on what is understood to be inside or outside the scope of the ‘could’. And this ambiguity undermines a number of arguments purporting to show that inadvertent wrongdoers cannot justifiably be blamed or punished. While not all opposition to blaming or punishing inadvertent wrongdoers rests on this ambiguity, some certainly does. And getting clear on this ambiguity is important if we're to sort good arguments against blaming and punishing inadvertent wrongdoers—if there are any—from bad ones.