I asked something like this. The reasoning if I can remember:

  1. You should not sell your daughter as prostitute.
  2. Rambam said that all sex outside marriage is prostitution.
  3. Therefore sex outside marriage is sin.

Okay I found problems here. Obviously nowadays, most prostitution are not done by parents selling their daughters.

However, that's kind of moot. I read further and see the reason why Rambam think all sex outside marriage is prostitution. Why does the Rambam (Maimonides) equate all sex outside marriage as prostitution?

Rambam is concerned with kids not knowing who the father is. Hilchos Naarah Besulah 2:17

For [ultimately], a father will marry his daughter and a brother his sister, [for in a sexually permissive society] a [girl] may become pregnant and give birth without knowing who the child's father is.

But then again, we have paternity tests for that that's far more accurate than marriage.

Note: Nowadays, paternity fraud is more "rewarding" if the woman is married. Both sex with married women and sex with unmarried women are legal as long as you don't pay her. The former means the husband will be required to pay child support irrelevant of DNA tests results. So getting married means you're pretty much showing your back causing the very problem Rabam objects about sex outside marriage.

In other words, Rabam's main concern, namely paternity, is simply not mitigated by marriage nowadays. In fact, it's made worse.

  • 1
    Note, that this question applies only to those that apply this reasoning to that prohibition. Even then, the Rambam may have had other reasons, and only listed the one he found most relevant.
    – HodofHod
    May 3, 2012 at 11:37
  • 1
    See Shalom's answer to the linked question, which among other things addresses the paternity test angle.
    – Alex
    May 3, 2012 at 14:57
  • 1
    Also, from the point of Jewish law, marriage is a solid guarantee of paternity; a married woman's children are assumed to be from her husband. (Many U.S. states do the same - see here.)
    – Alex
    May 3, 2012 at 15:24
  • I vote to close as not a real question. It's very confusing what's being asked, and it is worded in a highly inappropriate way.
    – Seth J
    May 7, 2012 at 16:22
  • 1
    #2 and #3 is rethorical questions. C'mon. We already knows the answer. Yes. and Yes :)
    – user4951
    May 8, 2012 at 2:59

3 Answers 3


The Torah specifically states the prohibition against prostitution, in order to prevent the land to be filled with licentiousness: ולא תזנה הארץ ומלאה הארץ זמה. Rambam seems to be deducing the underlying reason for that concern of the Torah, in his statement:

For [ultimately], a father will marry his daughter and a brother his sister, [for in a sexually permissive society] a [girl] may become pregnant and give birth without knowing who the child's father is.

i.e. if this were common behavior, people would come to transgress other more serious Torah prohibitions which carry the penalty of cares (חיוב כרת).

However, it is a stretch to think that Rambam is actually saying the converse: that if there were no danger of people transgressing the prohibition of forbidden relations, then the land being filled with licentiousness would no longer be a problem. I think he was just stating what is the most serious consequence of prostitution. I don't believe Rambam is implying that it would be otherwise permitted.

  • 2
    Excellent! This is IMO the p'shat of the Rambam. "For a father will will marry his daughter and a brother his sister, " since it will no longer be common to know who the father is.
    – HodofHod
    May 7, 2012 at 16:50
  • I thought it means a father will offer his daughter in marriage (i.e. selling it). What's wrong with licentiousness?
    – user4951
    May 8, 2012 at 2:27
  • I think the original quotation should be for a father will sell his daughter. Where do you get that quotation?
    – user4951
    May 8, 2012 at 2:54
  • That quote is from the Rambam. It's the same quote that you used in your comment here. I found the source and quoted and linked to it in your question.
    – HodofHod
    May 8, 2012 at 2:58
  • @JimThio: I took the English quote from the link you posted. The Hebrew also very clearly says "marry his daughter". May 8, 2012 at 2:59

Your question involves many areas of discussion, but I will focus on the paternity test angle.

The invention of paternity tests solves a narrow slice of questionable parentage. It presupposes that we 1) know all possible candidates; 2) all parties are available and consent to contributing DNA for testing; 3) DNA testing equipment and expertise is readily available; and 4) can be determined within the window of time it is needed. Above all, 5) we need to actually know that parentage is in question.

A "loose woman" who does not dedicate herself to a single partner will introduce descendants of unknown parentage, leading to the concerns outlined in the cited Rambam.


Your question stems from a misunderstanding. You assume that the Rambam (and everybody else) learns that premarital relations are forbidden because of the problem of identifying the father. This is simply not the case. In fact, the halacha which I edited into your question (since it's the one you quoted elsewhere), isn't even the place where the Rambam forbids premarital relations, the Rambam is only discussing a father essentially "selling" his daughter in order to get the money that a seducer/rapist is required to pay the girl's father (himself). The Rambam discusses premarital relations in totally different place, and with a different reason.

From Chabad.org's Rambam Hilchos Ishus:

Before the Torah was given, when a man would meet a woman in the marketplace, and he and she desired, he could give her payment, engage in relations with her wherever they desired, and then depart. Such a woman is referred to as a harlot.

When the Torah was given, [relations with] a harlot became forbidden, as [Deuteronomy 23:18] states: "There shall not be a harlot among the children of Israel."4 Therefore, a person who has relations with a woman for the sake of lust, without kiddushin, receives lashes as prescribed by the Torah, because he had relations with a harlot.

Other Rabbis learn the prohibition from other Biblical verses, for example Ramban (Nachmanides) learns it from the verse: “And the earth shall not be filled with immorality” (Lev. 19; 29).

The Raavad, holds (from AskMoses.com):

The Raavad, according to most authorities, deduces it directly from the command to marry. Implicit in the command to marry, he says, is a prohibition of all nonmarital intercourse. This is technichally referred to as an "Issur assei."

As you can see, there's no reason that paternity test could or should change anything, since paternity is not the reason for the prohibition is not because of paternity. It's because G-d said so. Even if you say that the Rambam's paternity problem refers to general premarital relations (which, from context, I don't think it does) that's only a logical reason that fit with his times. The real reason that it's prohibited always remains the same:

G-d said.

The disagreement is only about where He said it.


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