How can the Rambam say that Kiddushin is a Mitzvah, against the Gemara?

Question

The Rambam in Hilchos Ishus 1:1 makes the following statement:

כֵּיוָן שֶׁנִּתְּנָה תּוֹרָה נִצְטַוּוּ יִשְׂרָאֵל שֶׁאִם יִרְצֶה הָאִישׁ לִשָּׂא אִשָּׁה יִקְנֶה אוֹתָהּ תְּחִלָּה בִּפְנֵי עֵדִים וְאַחַר כָּךְ תִּהְיֶה לוֹ לְאִשָּׁה שֶׁנֶּאֱמַר (דברים כב יג) "כִּי יִקַּח אִישׁ אִשָּׁה וּבָא אֵלֶיהָ":

Once the Torah was given, the Jews were commanded that if a man wants to marry a woman, he should take her first before witnesses, and afterwards she should be to him as a wife, as it says, “When a man takes a woman and comes upon her” (Devarim 22:13).

The Rambam clearly states that Kiddushin is a mitzvah (he should take her before marrying her - in the Hebrew text, the marriage is referred to as לשא, a form of נשואין, Nisuin, the second stage of marriage; therefore, this must refer to the first stage of marriage, Kiddushin).

Now read the Gemara in Moed Kattan 18b. Shmuel said that Kiddushin is permissible on Chol HaMoed, and the Gemara proposed that the fact that the earlier mishnah (Moed Kattan 8b) only forbade Nisuin, it must be that Kiddushin is permissible. The Gemara refutes this proof:

לא מיבעיא לארס דלא קעביד מצוה אלא אפילו לישא נמי דקא עביד מצוה אסור

[The Mishnah means to say:] It goes without saying that Eirusin [i.e. Kiddushin], by which he is not doing a Mitzvah, [should be forbidden,] but even Nisuin also, by which he does a Mitzvah, is forbidden.

Um...

How can the Rambam learn that Kiddushin is a Mitzvah, when the Gemara explicitly states that Kiddushin is not a Mitzvah?!

Answer 1

Rambam's son, R. Avraham, as cited in Kesef Mishne, end of Ishus 1:1, answers that the command is to marry with kidushin and nisuin, which is why Rambam refers to even the first part as a mitzva, meaning the start of one, but doing the first part alone doesn't do a mitzva. KM implies by his wording, q.v., that the main part of the dual mitzva is the second part.

h/t R. Tz'vi Hirsh Chiyes

Answer 2

I realize that both msh210 and IsraelReader already gave answers based on this source, but I think that neither one explained it fully/properly, so I would like to attempt to answer it myself.

This question was asked to R. Avraham the son of Rambam. This was his answer:

Birchas Avraham # 44

ואותה הקושיא שהקשית על עיקר דבריו לא קשיא עליה שבמנין המצוות בתחלת הלכה אמר שהמצוה לישא אשה בכתובה וקידושין ולא אמר לקדש אשה וכן אמרינן לישא דקא עבד מצוה וזה שאמר וליקוחין אלו מצות עשה לפי שהיא תחלת מצות הנשואין וכך אמר בתחלה יקנה אותה תחלה בפני עדים ואחר כך תהיה לו לאשה שנאמר כי יקח איש אשה ובא אליה אבל קידושין בלא נישואין ודאי לא השלים המצוה עדיין ומצות פריה ורביה מצוה אחרת היא שמצות פריה ורביה כשיהיה לו בן או בת קיים המצוה ומצות הקדושין והנשואין אפילו יש לו כמה בנים וכמה בנות ויש עמו כמה נשים כל אשה שירצה לישא אותה מצוה עליו שישא אותה בקדושין ועיין בדבריו ז"ל בספר מצות יתבאר לך ההפרש שביניהם ואין בנו צורך להאריך בדבר זה

My understanding of this is as follows: Rambam holds that there is a mitzvah of marriage which is made up of two components. 1. Kiddushin 2. Nissuin. If one performs Kiddushin but never gets around to doing Nissuin, he has started the mitzvah but has not completed it, and thus he is not considered to have fulfilled the mitzvah.

Therefore, the Talmud in Moed Katan means that when one does Nissuin he is fulfilling a mitzvah (because having already done Kiddushin, he is now completing the mitzvah) but when one does Kiddushin he is not fulfilling a mitzvah (because not having done Nissuin, the mitzvah is incomplete). This explains how Rambam's view is to be reconciled with the Talmud.

As for how, R. Avraham fits this explanation into Rambam's words (or how he derives it from Rambam's words), I believe the following is correct:

There is no indication of this explanation from Sefer Hamitzvot. There Rambam lists two mitzvot, one about procreation (#212) and one about marriage (#213). It is certainly implied that these are two separate mitzvot (i.e. one can fulfill the mitzvah of marriage without procreating), but there is no indication here that the mitzvah of marriage consists of Kiddushin + Nissuin. If anything, the implication there is that Kiddushin is the entirety of the mitzvah of marriage, as that is all that is mentioned there.

However, the indication that Rambam's view is in fact that only Kiddushin + Nissuin = the mitzvah of marriage, is in Mishneh Torah. In the beginning of Hilchot Ishut Rambam lists the mitzvot that are included in this section. The first one is:

לישא אשה בכתובה וקידושין

To marry a woman, granting her the rights of the formal marriage contract (ketubah) and sanctifying the relationship through the rites of kiddushin; (Chabad.org)

R. Avraham picks up on the fact that Rambam does not say simply "לקדש אשה" which would be sufficient if Kiddushin was the entirety of the mitzvah, but instead says "לישא אשה בכתובה וקידושין" which indicates that there is an additional component, namely, Nissuin.

R. Avraham does not note this, but in Shemonah Perakim (Chapter Eight) Rambam has a similar formulation:

לפי שהאשה הזו אם לקחה בכתובה וקדושין והיא מותרת לו ונשאה לפריה ורביה הרי זו מצוה (Kafih translation, my emphasis)

R Avraham then clarifies that the mitzvah of marriage (i.e. Kiddushin + Nissuin) is distinct from the mitzvah of procreation. The mitzvah of procreation is fulfilled by having a surviving son or daughter. The mitzvah of marriage can be fulfilled even if you already have many sons, many daughters, and many wives. For any woman that you want to marry, there is a mitzvah to marry her via Kiddushin + Nissuin.

Answer 3

Good question. The "Kessef Mishnah" on the Rambam (Ishus 1:3) quotes R' Avraham, the son of the Rambam, who noted that this question was posed to him.

Before we get to his answer, I note that the Rambam in Hilchos Ishus 1:1 is not the only source for this position. It is also found in "Sefer HaMitzvos" (Asei 213):

הצווי שנצטוינו לבעול בקידושין: במתן דבר ביד האישה, או בשטר, או בביאה - וזוהי מצות קידושין.

The 213th mitzvah is that we are commanded to acquire [by kiddushin1] a woman before having relations with her: either by giving her something [of sufficient value]; by giving her a document [of marriage]; or by having marital relations [for the purpose of kiddushin]. This is the mitzvah of kiddushin.

Here is the "Kessef Mishnah" in the name of R' Avraham, the son of the Rambam:

כתב הר"א בנו של רבינו, שהקשו לו על מה שכתב רבינו מצות עשה של תורה לקדש את האשה ממ"ש בפרק אלו מגלחין (מ"ק דף יח) לא מיבעיא קאמר לא מיבעיא לארס דלא עביד מצוה שאסור אלא אפילו לישא דקא עביד מצוה נמי אסור. ותירץ, שבמנין המצות בתחלת ההלכה אמר שהמצוה לישא אשה בכתובה וקידושין, ולא אמר לקדש אשה, וזה שאמר וליקוחין אלו מצות עשה, לפי שהיא תחלת מצות הנישואין, אבל אירוסין בלא נישואין ודאי לא השלים המצוה עדיין:

My understanding of his answer is as follows. Kiddushin alone is not a mitzvah (which is what the gemara in Moed Kattan is referring to). The mitzvah is to procreate (Asei 212), with a woman whom we have previously given Kiddushin to.

I conclude with a "proof" that the Rambam uses (Asei 213) to support his position:

ובפרוש אמרו על קידושין בביאה שהם דאורייתא. הנה נתבאר שמצות קידושין דאורייתא.

Our Sages (Kiddushin 9b) stated explicitly that kiddushin by means of relations is a Torah law. This statement proves that kiddushin counts as a law of the Torah.