Final answer:
Montaigne believes repentance is necessary when something bad occurs that is within our ability to prevent. This belief is connected to broader ethical philosophies regarding personal responsibility and the exercise of free will.
Step-by-step explanation:
According to Montaigne, repentance is necessary if 'something is bad' and 'it was in our power to prevent'. The philosophy of Montaigne holds that we should feel remorse for bad outcomes that we could have prevented. This ties in with ethical principles espoused by several philosophers, including the idea that we should strive for good and prevent evil when it is within our power to do so. He also supports the view that while some evil may be inevitable, we are responsible for our reaction to it, and the way we choose to correct or deal with it, which is aligned with the concept that we must exercise our free will responsibly.
Furthermore, the notions by philosophers like Socrates, that individuals do not intentionally choose evil, but may do so out of ignorance, reinforces Montaigne's position that knowledge and understanding of one's actions and their potential to prevent harm are integral to moral conduct and therefore, to the need for repentance when those actions result in preventable negative outcomes.