There is a popular moral question - if you had access to a time machine that was capable of allowing you to do so, should you go back in time and kill Hitler when he was a child, before he had a chance to cause the Holocaust? I was thinking that this is an interesting question to try to deal with from a halachic perspective. Presumably it isn't something that anyone has written a psak on, but I'm sure that there are elements of it which can be deduced, so I'm just looking for a good answer with supporting sources - nothing definitive!

Let's assume for the purposes of this question that you can be definite that he will definitely do what he did, and that the only way to stop him would be to kill him, and not to stop him in any other way.

The answer could be that you have an obligation to, that you are permitted to, or you are forbidden from doing so (or possibly something more complex).

I think that the first question is whether someone should be punished for something that they haven't done yet? If not, can you kill them to save many other people?

Feel free to throw in other aspects to this that I've not considered.

  • I don't have any sources yet, but if I remember, concerning a rodef, killing should be the last result. You could seriously maime the person in ordertostop him. Though concerning Hitler, in this situation, he's a child, he didn't kill anyone yet so you can't kill him. Though once he killed someone you could kill him if that's the only way to stop him due to being a rodef and because of the noahide law of murder. I don't think there's a chiouv to invent a time machine See: sefaria.org/Minchat_Chinukh.600.1.2
    – Shababnik
    Dec 4, 2023 at 22:13
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    @Shababnik Surely the point of killing a rodef is precisely that they haven’t killed anyone yet?
    – Zarka
    Dec 4, 2023 at 22:38
  • @Zarka Hitler as a child hasn't killed anyone yet a rodef is only someone who is in the act of killing someone or has previously done so.
    – Shababnik
    Dec 4, 2023 at 22:52
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    @Shababnik Is there a source which says how close in time the rodef has to be to the death of their prospective victim before they become a rodef?
    – Zarka
    Dec 4, 2023 at 23:14
  • @Zarka when a rodef is chasing to kill. Going back in time knowing someone will kill when he grows up is not in that time frame I believe
    – Shababnik
    Dec 4, 2023 at 23:23

5 Answers 5


As the question says this isn't a definitive answer but other than the case of a direct rodef there are other Torah sources indicating that the correct thing is to kill a baby Hitler.

Sanhedrin 71b בן סורר ומורה נידון על שם סופו ימות זכאי ואל ימות חייב

A stubborn and rebellious son is sentenced to death on account of his ultimate end. It is better that he should die while he is still innocent, and not die after he becomes guilty.

The next Mishna (72B) says הבא במחתרת נידון על שם סופו

A burglar who is found breaking into a house it may be killed by the owner of the house with (see Exodus 22:1). He too is sentenced on accounts of his ultimate end (that he is assumed to be willing but not necessarily looking to kill the owner of the house)

The Gemora discuss various cases and seems clear that even if the chance of the burglar killing the owner of the house are not that high he still may killed if the possibility exists. Including if the burglar is a child.

Putting them both together it come out that (conceptually) even when someone did not do an avaeira that carries the death penalty if it is clear they will present a serious danger to lives of others they are to be killed before they have the opportunity to do so. Even a child.

As far as the issue addressed in the OP of I think that the first question is whether someone should be punished for something that they haven't done yet? killing a baby Hitler would not be a punishment. Killing a rabied dog isn't a punishment. Of more relevance killing the Amalekite children is not a punishment either. It is just a means to an ends of saving others from a menace to society . A baby Hitler isn't more innocent than a baby Amalekite child.

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    Ben sorer is a completely unique scenario
    – Shababnik
    Dec 4, 2023 at 23:24
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    Ben sorer is a completely unique scenario . So is killing baby Amalekites. They both indicate however that CONCEPTULLY the Torah has people who will grow up to be evil killed before they sin.
    – Schmerel
    Dec 4, 2023 at 23:27
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    The second example is good. Dec 5, 2023 at 0:25
  • @Schmerel Killing a baby Hitler makes sense since we know who the baby will grow up to be: Adolf Hitler. However, killing baby Amalekites is murder. Since there is no way of knowing that the baby Amalekites will grow up to be terrorists. Killing them is evil.
    – Turk Hill
    Dec 5, 2023 at 1:45
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    Being that the Amalekites haven't been around for thousands of years not enough is known about the nature of the mitzva or the nature of Amalekites to know it's exact circumstances but God saying to kill them is enough to know that it is the right thing to do, If you want to go with secular "morals" the fact that killing a baby Hitler is even a major moral question is enough for me to know that this is not the place to be looking for moral guidance. I will nor respond further on this issue.
    – Schmerel
    Dec 5, 2023 at 2:27

I have some thoughts, but I'm no theologian, so take my conclusion with a grain of salt.

Menashe ben Chizkiya is an interesting corollary which suggests that it would not be permitted. I'll review the story briefly:

Chizkiya became aware through prophecy that he would have a son who would become a terribly wicked king over Israel. As a result, he decided not to have children. He was punished for neglecting the mitzvah of having children, and told by Yeshayahu that he must allow the prophecy to run its course. He repented and had a son, Menashe, who committed many murders, forbade Torah study, and propagated idol worship throughout Israel.

Yishmael is also saved from thirst miraculously despite angelic dispute, because he was worthy of it at his time of need, even though he would later become very wicked and his descendants would lead many Jews to die of thirst.

Let's contrast these two examples with the case of Micha -the baby in the wall (not the prophet). In that situation, Moshe Rabbeinu begged G-d to save Jewish children from being built into walls. G-d told him that it would be better not to intervene,but he could save one and see what happens. He ended up saving a baby, who became very wicked. Here, G-d suggested allowing the killing to take place because of who that baby would become.

Perhaps if someone else is destroying the baby threat, one should not intervene, but one may not violate even a positive commandment (having children) to eliminate the threat actively, and must even save them (like G-d saved Yishmael).

  • If you already knew that killing a baby Hitler was wrong then the story with Chizkiya would prove that you should not do so anyway. The question is if it wrong to do so to begin with.
    – Schmerel
    Dec 5, 2023 at 2:36
  • @Schmerel but it wasn't clear from the prophecy that it was wrong. It just showed him what would happen. The reason it was wrong was because he was neglecting a positive commandment. Similarly, one might say that the reason it would be wrong here is because killing is neglecting a commandment too. Dec 5, 2023 at 4:00
  • You didn't mention ben sorer umoreh who is killed על שם סופו. The mefarshim deal with reconciling this with Yishmael
    – wfb
    Dec 5, 2023 at 13:54

There is a law of killing the pursuer (rodef) which commands us to kill a murderer attempting to kill someone else, before he has done so. The Rambam codifies this in MT Rotzeach uShmirat Nefesh 1:6-7.

When, however, a person is pursuing a colleague with the intention of killing him - even if the pursuer is a minor - every Jewish person is commanded to attempt to save the person being pursued, even if it is necessary to kill the pursuer.

What is implied? If the rodef was warned and continues to pursue his intended victim, even though he did not acknowledge the warning, since he continues his pursuit he should be killed.

If it is possible to save the pursued by damaging one of the limbs of the rodef, one should. Thus, if one can strike him with an arrow, a stone or a sword, and cut off his hand, break his leg, blind him or in another way prevent him from achieving his objective, one should do so.

If there is no way to be precise in one's aim and save the person being pursued without killing the rodef, one should kill him, even though he has not yet killed his victim. [...]

But note the criteria: one has to warn the pursuer and there has to be no other way to prevent him from killing. This would not apply to a baby since presumably there are other ways to prevent him from killing, although it would apply in your theoretical scenario ("definite that he will murder", "the only way to stop him would be to kill him").


There's no doubt that we're dealing with redifah as an area of law here. So it seems to me there are two questions:

  1. Can a child Hitler be regarded by a time-traveller as a rodef?
  2. And if so, is it legitimate to kill him?

Question 1 is complicated by the sci-fi element in the question. Ordinarily, someone can only be considered a rodef when it can be inferred from their behaviour that they are about to kill. There is a useful discussion of the issue on pages 8-9 here.

So, for example, if Reuben returns home from work unexpectedly, finds his wife in bed with Shimon, and, enraged, grabs a knife and runs towards Shimon, there is no doubt that Reuben is a rodef. But 24 hours earlier, it would have been impossible to label him a rodef: nobody would have had the slightest idea that the following day's events would happen.

However, the time travel issue means we have to imagine that, 24 hours earlier, our time-traveller did in fact know with absolute certainty that Reuben would, if not prevented, kill Shimon. In that case, I imagine the halachah might say that he can indeed be considered a rodef.

Obviously there are no responsa about time travel, but see this ruling from Rav Feinstein about conjoined twins: obviously we can't draw behavioural inferences from infant twins, but if it is medically certain that twin A is the one which is endangering the life of twin B, it is legitimate to regard twin A as a rodef. Perhaps we could analogise medical certainty to time-travelling certainty?

Question 2 is a lot simpler: as others have said above, even when we have a rodef, killing them is only legitimate when it is the only way of saving their would-be victim(s). In the case of a child Hitler, there would doubtless be a number of options short of killing – to take a random example, kidnapping him and depositing him in an orphanage in England or America.


It's hard to ask about the halacha because there is no time travel in real life. However, we can ask the hashkafa, which will (and does) inform the halacha. A very famous Torah principle is:

We only judge a person by what their position is right now.

Emphatically, if we asked Hashem if we could go back in time and kill Hitler as a baby, he would say NO!

Just like He said no to killing Yishmael (He Himself regrets 4 things every day, and one of them is this decision! See Sukka 52b). Rashi on Bereshit 21:17 on "באשר הוא שם":

WHERE HE IS — According to the actions he is now doing shall he be judged and not according to what he may do in future. Because the ministering angels laid information against him, saying, “Master of the Universe, for him whose descendants will at one time kill your children with thirst will You provide a well?” He asked them, “What is he now, righteous or wicked?” They replied to him, “Righteous.” He said to them, “According to his present deeds will I judge him.” This is the meaning of what is written: “[For God hath heard the voice of the lad ] באשר הוא שם in that condition in which he now is” (Genesis Rabbah 53:14). Where did he (Ishmael) kill Israel with thirst? When Nebuchadnezzar carried them into exile — as it is said, (Isaiah 21:13, 14) “The burden upon Arabia … O ye caravans of Dedanites, unto him that is thirsty bring ye water! etc.” When they were bringing them near the Arabians the Israelites said to their captors, “We beg of you bring us to the children of our uncle, Ishmael, who will certainly show pity to us”, as it is said, “O ye caravans of the Dedanites (דדנים)”; read not דדנים but דודים, kinsmen. — These indeed came to them bringing them salted meat and fish and water-skins inflated with air. The Israelites believed that these were full of water and when they placed them in their mouths, after having opened them, the air entered their bodies and they died (Eichah Rabbah 2:4).

Ostensibly, the main message of the book of Yonah is this very message: we don't take prophetic future considerations into account! Yonah was avoiding his mission because, in his protective leadership of the Jewish people, he didn't want to help the city of Nineveh do teshuva. Why? Because it would lead to a future claim against the Jews, i.e. "even the people of Nineveh did teshuva!" Worse, the Torah records that not long after they were spared due to their teshuva, Ashur invaded Eretz Yisrael, sacked cities and exiled the tribes.

  • 1) That's only taking into account the aspect of punishment, not saving people. 2) From the perspective of the time traveller, this is the past and it has already happened, so that may affect things 3) those sources are describing Hashem punishing people, not other people (although I guess you probably can make a kal v'chomer there) Dec 5, 2023 at 12:28
  • @MosesSupposes I think that in the cases I brought, Hashem is teaching us how to act - that's what all Torah events are about, a timeless lesson for us. He Himself can do as He pleases, and He did indeed do that, remember that Micah was meant to be a brick in an Egyptian wall, but Hashem let him live to show Moshe that these people were not meant to live due to their future sins. I also argue that there's no difference between prophecy and hindsight, from Hashem's POV. As for your 1) It is indeed saving people, I don't get what you mean
    – Rabbi Kaii
    Dec 5, 2023 at 12:32
  • 1) the aspect of him being a rodef Dec 5, 2023 at 12:50
  • @MosesSupposes that applies to Yishmael and Nineveh
    – Rabbi Kaii
    Dec 5, 2023 at 12:55
  • @RabbiKaii I’m not sure that reasoning works here. The intrinsic nature of redifah is its reliance on potential future action.
    – Zarka
    Dec 5, 2023 at 13:13

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