Moreover, there are other stories in the Hebrew Bible on which an argument to the conclusion that the deontological status of at least some actions depends on divine commands can be based. These stories recount the incidents commonly described as the immoralities of the patriarchs (Abraham, Moses); they are cases in which God commands something that appears to be morally wrong. The most famous of them is the divine command to Abraham, recorded in Genesis 22:1-2, to sacrifice his son Isaac. According to a medieval exegetical tradition, Abraham did no wrong in consenting to slay Isaac and would have done no wrong if he had slain Isaac (see powerpoint on this site). Thomas Aquinas explains that, when Abraham consented to slay his son, he did not consent to murder, because his son was due to be slain by the command of God,

“Who is Lord of life and death: for He it is Who inflicts the punishment of death on all men, both godly and ungodly, on account of the sin of our first parent, and if a man be the executor of that sentence by Divine authority, he will be no murderer any more than God would be.”  Aquinas

In other words, Thomas thinks that, because Abraham would have been carrying out a death sentence imposed by God if he had slain Isaac in obedience to the divine command, he would not have committed a murder and so would not have done wrong if he had killed Isaac.

Andrew of Neufchateau reaches a similar conclusion. He argues that there are actions, such as HOMICIDE, which, when examined by natural reason, seem to be wrong but are not necessarily sins with respect to God’s absolute POWER. Abraham, he says,

“wished to kill his son so that he would be obedient to God commanding this, and he would not have sinned in doing this if God should not have withdrawn his command.”Andrew of Neufchateau

In other words, for Andrew, because God’s absolute power determines whether a homicide is a sin, Abraham would not have sinned and so would have done no wrong if he had killed Isaac in obedience to the divine command.

What the two medieval exegetes share is the conviction that the slaying of Isaac by Abraham, which would be wrong in the absence of the divine command, would not have been wrong and, indeed, would have been obligatory, given its presence, if it had not been withdrawn. And it is hard to see how Thomas or Andrew could resist the conclusion that any divinely commanded homicide would be obligatory. Lordship over life and death and absolute power, which are the divine attributes they take to explain why God’s command to kill Isaac imposes an obligation on Abraham, would be properties of God even if divine commands to kill were numerous.

So it seems that the considerations mobilized to defend Abraham against the charge of immorality can be generalized to support the conclusion that whether any action is morally obligatory depends on whether it is divinely commanded.