Our Gemara on amud aleph teaches that though it is permitted to kill an informer, there is an opinion that one may still not take his possessions. (In times where the local government was cruel and unjust toward Jews, an informant in the community posed mortal danger.) The rationale for this distinction is provided by the Gemara:

Perhaps he will have righteous children, and it is written: The wicked may prepare it, but the just shall put it on (see Job 27:17).

We see from here a Torah ethic. Before we take an action, even when justified, we must consider the far-reaching implications to later generations.  

We find a similar teaching in the Midrash regarding Moshe’s killing of the Egyptian who was beating a Jew with murderous intent.  The verse says, “He looked here and there and saw no man” (Shemos 2:12).  While the pashut peshat is that Moshe checked to see if the coast was clear, this might be seen as a lack of faith, and so the Midrashic explanation is different. Using his divine Ruach Hakodesh superpowers, Moshe looked into the future to make sure that there were no worthy descendants that might justify sparing this Egyptian’s life. (The pashut peshat is not necessarily a diminution of Moshe’s faith, as even a prophet is required to take precautions and not rely on miracles, see Chulin (142a).)

But you might ask, if we are so concerned about later generations, why do we kill the informer? Should we not also take into account his descendants, consistent with Moshe Rabbenu’s practice?

This shows the wonderful and ever practical side to Torah ethics. There is a hierarchy of concerns and values. For example, though we consider it sinful to cause an animal to suffer, we still eat them.  Likewise, though there is a concern about later generations, since this Quisling presents clear and present danger to the community, we do not quibble over vague ethical concerns. But that is only in regard to mortal danger; when it comes to financial concerns we will take his descendants into consideration.

Regarding ethics, we must be grounded in the teachings and traditions of the Torah. Otherwise, it is easy to lose a sense of priority, such as the way the “woke mob” preaches “me too” and “silence=violence”, but disregards the sadistic and monstrous sexual abuse committed by Hamas. Midrash Tehilim (7:20) makes an astute observation about human nature: “One who shows mercy when it is appropriate to be tough, will eventually be cruel when he is supposed to be merciful.”  This is what happened when King Shaul felt compassion for the King of Agag, and spared his life, yet later on, went on a genocidal rampage against the cohanim of the City of Nov for their crime of insurrection.