Is there any reason that we couldn't believe in life on another planet somewhere? Is there any source that indicates to the contrary?

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    Highly related:judaism.stackexchange.com/q/9197
    – Fred
    Commented Jul 24, 2014 at 23:54
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    I realize you are asking for proof of negation, but I will just mention that in the book Thinking aloud, Rav Soloveitchik is recorded as saying alien life is definitely possible and that there may even be an Am Hanivchor for that planet!
    – user6591
    Commented Jul 25, 2014 at 1:58
  • @Fred My question could really be taken as a subset of that question. But I don't think it's a dupe. Commented Jul 25, 2014 at 3:09
  • Why doesn't the reference to the Sefer HaIkkarim stated there satisfy this question?
    – Yishai
    Commented Jul 25, 2014 at 13:21
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    What do you mean by "believe in"? Believe simply that "life on another planet somewhere" exists? Believe that it represents some kind of deus ex machina?
    – Tamir Evan
    Commented Jul 25, 2014 at 16:00

6 Answers 6


The Sefer Hikrim brings his rebbe which held that there are no aliens. However the Sefer Hikrim himself argues and holds that there are aliens. He brings a proof from the possuk in Shoftim which says "oro mroz", which the gamera in Moed Katan (Rashi brings this) says roz is a star, and the passuk concludes "arur yoshveha" cursed are its inhabitants, clearly there is some form of life in space.

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    Do you know where in Sefer HaIkkrim this is said?
    – Yishai
    Commented Aug 12, 2014 at 23:31
  • Do we have any reason to think י.ש.ב. must apply to live things?
    – Double AA
    Commented Aug 13, 2014 at 0:07
  • More important (to me as the OP) is did his Rebbe have any source or indication? Commented Aug 13, 2014 at 0:38
  • how is this a reason that we couldn't believe in aliens.
    – ray
    Commented Aug 31, 2015 at 16:05
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    @ray It's not. It's saying that there is no reason why we couldn't believe in aliens.
    – Daniel
    Commented Aug 31, 2015 at 17:29

In this article, Rabbi Aryeh Kaplan sources and discusses opinions on both sides of the argument, bringing various proofs and questions.

Chasdai Crescas says aliens can exist, Yosef Albo said there cannot be any other beings with free will, apparently the only objection with believing in aliens centers around this issue of free will. Rabbi Kaplan also quotes the Sefer HaBris who took the middle road saying they exist, but do not have free will. Rabbi Kaplan goes on to say that the Zohar seems to support belief in extra terrestrial life.


User6591 answered based on the essay entitled "On Extraterrestrial Life" by Rabbi Kaplan that there are mutiple opinions. That essay is written in the same author's book, Moreh Ohr on pp. 47-50. All of the relevant information is laid out and presented with the relevant passages quoted in their original. He then concludes with this:

We see from this [starting on p. 47] that there is a singular species in the world that is capable of free will, Torah, reward and punishment which are the purpose of creation. This is mankind, to whom God has given The One Torah. It is however possible that there exists many species of living creatures on other stars i.e. planets, which may even be capable of intelligence and wisdom, just not freewill. The subject of freewill is but a very small item as it is, that cannot be verified in science [or by scientists], only by belief in our Torah. And if they do find additional species of living creatures, we have already learned from the Torah that don't have freewill.


Rav Meir Mazuz has a very interesting article on it which he claims there are no life on other planets as on earth.

The torah's word is above everything, above all the professor's, above all the scientists. All their words are null and void against one word of torah!

For example: "in the beginning, G-d created the heavens and the earth" (Gen.1:1). The deniers came along and said: This is false! The earth is part of the heaven. We once had a book called "the heavens" (by the french astronomer, K.Palmerion). He wrote there: "the heavens are everything. Don't think the heavens are one thing and the earth is another. Rather, the earth is just one planet in the heaven!" He was not the first to say this. After it was discovered that all the planets revolve around the sun, then all the scientists also held this view.

Thus they said, what is this: "the heavens and the earth!?" (Gen 1:1)

When they reached this conclusion, they asked themselves: "just like there are human beings on the earth, so too there must be on other planets. There must exist also on the moon, on mars, on venus, mercury, etc.

In truth, there were some torah sages who thought like this. In the days of the Chacham Tzvi, there was a Rav talmid chacham, tzadik, G-d fearing, by the name of David Nito, author of the book Matei Dan. There they asked him: "what do you think of what the scientists say that there are human beings on the moon?". He answered: "Why not? If they tell you there are human beings in India, will you say they walk upside down or they have three eyes?! Of course not. All are the same. So too here. All the planets are the same".

Eventually, this matter was proven false. When? About fifty years ago, when they went up on the moon and saw no men, no horses, etc. There's no air and no water. All desolate wasteland (at that time, Rabbi Nissan Pinson told me: "slowly, slowly they will realize that there is no place fit for life like planet earth".)

For the "heavens" is a vast sphere which has nothing, while the "earth" has so many interesting things. There are human beings, animals, trees, grasses, and there are people who recognize their Creator, pray to Him and thank Him.

This is what is written: "in the beginning, G-d created the heavens and the earth". It has already been fifty years, since the scientists search against this. But in truth, there is nothing. Period.

One word of torah is worth more than all the scientists' words together! They are all as dust and ashes against it. So too, for everything else written in the torah. (from Rabbi Mazuz's weekly class. Parsha Tzav 5778) note: this phenomena is happening also in physics, biology, cosmology, etc. For example, the scientists expected living cells to be simple but even the simplest bacteria turned out to be an intense world of bewildering complexity. Likewise for everything. Even the tiny atom is an intense world of mathematics which gets more complex the more you go in.

  • Thanks for the source. He does seem to take it for granted that it is problematic to claim there is life elsewhere in the Universe, but it's unclear exactly from where he gets that starting point. Commented Mar 24, 2019 at 5:36

According to my understanding of the Torah, and my logic:

  1. Torah is one and unchangeable

  2. Only Adam was created בצלמנו כדמותנו and יודע טוב ורע and only his descendants can qualify as such.

  3. While we didn't see men leaving Earth for other planets, there could be no human-like, sentient life besides humans.

If you asked such a question to Rambam or the Geonim or the Sages that would be definitely considered heresy as the Earth was flat and there was a clear distinction between the Earth and Heavens (see Rambam's Yesodey Hatorah - everything he spoke of was physical to him and his generation). All of the sudden אנן סהדי that we can fly into the skies and there's no רקיע - firmament whatsoever, so we immediately rewrite Judaism to accommodate for that apparent knowledge.

Therefore the most problematic part in this question - what do we call Judaism? How far can we deviate from our Rabbis' understanding of the Torah to fit it into contemporary science? I really don't know what the limits are.

  • 1. I think you mean to say sentient, not just conscious, life besides humans. Animals are also conscious, but they’re not sentient. 2. There’s a big difference between “rewriting Judaism” when it comes to things like the רקיע, which don’t make such a big impact on Halacha and Hashkafah, and “rewriting Judaism” to completely overturn a basis of it - that man is unique in his free will.
    – DonielF
    Commented Mar 21, 2019 at 14:09
  • @DonielF 1. maybe, feel free to edit. 2. "according to Judaism" is a very hard to define term. My point is to be aware of the relativity of it and our ability to bend Judaism into just about anything.
    – Al Berko
    Commented Mar 21, 2019 at 14:19
  • To a certain extent, yes, Judaism is a bit flexible. But there are certain lines which cannot be crossed: you can't, for instance, torture Judaism into saying that idolatry is ordinarily okay, or that one can wantonly break Shabbos because he feels like it when he knows better. There are certain facts which are immutable, and the uniqueness of man in terms of his sentience and free will are among them. I agree with everything in this post, until the horizontal rule.
    – DonielF
    Commented Mar 21, 2019 at 14:22
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    Re the Kerubim: take a look at Shemos 20:20 - they're not idols if and only if they are made in a specific way. If they're made even slightly differently, they are indeed considered idols. Re Shabbos: Perhaps that's true, but that doesn't mean it's permissible to break Shabbos in such a case; it just means that we're human.
    – DonielF
    Commented Mar 21, 2019 at 14:28
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    Points #2 and #3 need a source
    – robev
    Commented Mar 22, 2019 at 17:54

To say that there cannot be other creations or life existing elsewhere in the universe would be placing a limitation on Hashem, which would be kefira (heresy).

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    The question isn't about whether there could be aliens. It's about whether we can believe that there are aliens. Of course God could create aliens just like he could create saber-tooth chickens
    – Daniel
    Commented Sep 22, 2014 at 22:43
  • are you suggesting if the possibility of life existing elsewhere became a reality there might be a prohibition against believing they exist? your comment makes no sense at all
    – Dude
    Commented Sep 24, 2014 at 0:03
  • The question is about believing that aliens exist right now. Not that they could exist at some unknown time in the future.
    – Daniel
    Commented Sep 24, 2014 at 0:06
  • my answer remains the same and is relevant. it will be more apparent when you stop getting hung up on using the word "belief"
    – Dude
    Commented Sep 29, 2014 at 2:22
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    No, it's not relevant. It's a question of what could be vs. what is. You say that God can create aliens. I agree. But maybe he didn't create aliens even though he could
    – Daniel
    Commented Sep 29, 2014 at 19:29

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