He said:
“The answer is that good and evil have a foundation among the first principles of reason: our knowledge that gratitude to a benefactor, fairness, and justice are good, and that lying, injustice, and oppression are evil. Whoever denies this defies the judgment of all rational people. Some rational people, however, say: ‘I do not know this through self-evident reason; rather, I know it through inquiry and transmitted reports.’ Such a person acknowledges good and evil but claims a different means of knowing them from that generally recognized. We therefore discuss this with him and explain that the people of the pre-Islamic age, idol worshippers, and those whom the call has not reached know this just as adherents of revealed religions do. Thus, no means of knowing it remains other than reason.
“Moreover, eternity and temporal origination have a foundation among the first principles of reason, yet disagreement about them exists. We do not say that our opponent is defying his own reason.
“It was argued that all who hold that reason imposes obligations and prohibitions agree that it does so only when a prompt reaches it. Once this is established, we say: that prompt must come through a report conveyed by revelation, not through passing thoughts. Such thoughts may come from an angel, from Satan, from an agitation of bile, or from something similar. Since these are possible sources, we pay no heed to their prompting, but attend instead to that through which they have effect, namely a report conveyed by revelation. When no such report is present, it follows that there is neither obligation nor prohibition in this matter.”
He also said:
“The answer is that a person must be prompted to recognize the goodness of gratitude when a blessing from a benefactor who intended to do him good comes to mind. Once the benefactor’s blessings upon him come to mind—as we have described—his reason necessarily obliges him to be grateful, whether the prompt is a whispering or an inspiration. Likewise, whenever ingratitude for a blessing comes to mind, he recognizes its evil. And whenever it occurs to him that an evil act might well cause his ruin and punishment, and that its opposite might be a means