Mi Yodeya is a question and answer site for those who base their lives on Jewish law and tradition and anyone interested in learning more. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Suppose we one day find an extraterrestrial walking on our planet that originated from another planet. The alien quickly learns all about religion and now wants to become a Jew. Do we let him?

Remember: Aliens don't have to be three-eyed, green-skinned creatures. Perhaps they will even look and function exactly like we do!

(of course, the premise of this question is that Aliens do exist)

share|improve this question
Only if they're not from Meroz... – yoel Jun 15 '12 at 22:27
Wouldn't it basically boil down to the question of whether halachah would consider them human? If not, then no matter how sentient they are, they could no more be considered Jewish than a golem. [I imagine - though I'd have to look for sources - that the criterion would be whether they're born from a human mother (compare Bechoros 8a, הדולפנין פרין ורבין מבני אדם), so Spock might be considered halachically human, but Deanna Troi would not.] – Alex Jun 15 '12 at 22:32
@HodofHod That's correct. Once you take that as a given the question doesn't start. [I would, however, accept an answer if it emerges that all Rabbis agreed there was no life -- since if true, that would be an actual answer] – yydl Jun 17 '12 at 2:48
Too localized....to your imagination. – Seth J Jun 17 '12 at 3:03
@SethJ Because the probability of it happening is more than 0. That's all. And as far as I can tell it's a legitimate question much the same any other question is... – yydl Jun 17 '12 at 3:49

As discussed in another question, whatever extraterrestrial life exists does not have free will, and would therefore not be capable of accepting the moral responsibility of conversion.

share|improve this answer
There is no pasuk that says that aliens cannot have freewill. I understand that there are various sources on the topic, but the fact of the matter is that none is better than a Gemara, and even in the Gemara this kind of thing would be דברי אגדה which we could halachically wiggle out of. There therefore is no true Jewish belief on the issue even if there is Jewish thought. To not make that distinction is to paint ourselves into a corner for no reason. The correct answer, in my opinion, is "who knows, let's wait and see and figure it out then." – Dov F Jun 27 '12 at 19:57
Clearly you are correct that this question is only hypothetical, and any true ruling would depend on the circumstances of the case. However, this would seem to be the most reasonable conjecture. – Baruch Jun 27 '12 at 21:06
See comments on that question starting here judaism.stackexchange.com/questions/9197/… – Double AA Jul 1 '12 at 7:21
@DoubleAA: I answered your question there. – Baruch Jul 2 '12 at 19:27

It would depend. If there are Jewish aliens then a non Jewish alien will be able to convert. However if there are no Jewish aliens then a alien would be unable to convert. This is similar to animals. Since there are no Jewish animals therefore a animal can not convert. (Hilchos Chayos 25:10)

All kidding aside. Rabbi Avigdor Miller Zatzal clearly said many times that there is no humans or aliens on the other planets.

share|improve this answer
I'm confused: is Hilchos Chayos a real work? – Double AA Jun 27 '12 at 19:15
It is a figment of my imagination, similar to the questionnaire. – Gershon Gold Jun 27 '12 at 19:17
Ahh well then -1. The question clearly said it assumes they exist, and it is clear that R Miller is not the only opinion on this matter judaism.stackexchange.com/a/9203/1274 – Double AA Jun 27 '12 at 19:18
Also, I'm quite confident that yydl exists. – Double AA Jun 27 '12 at 19:18
DoubleAA - Sorry that I alienated you. – Gershon Gold Jun 27 '12 at 19:33

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.