Must tzitzis start out as valid?
Rabbi Shmuel Wise, Maggid Shiur at RealClearDaf.com
The daf that falls out on Yom Kippur discusses this issue. Rav Huna rules that if someone put tzitzis on a three-cornered garment (which has no tzitzis obligation) and then created a fourth corner and added tzitzis to that corner, the tzitzis are not valid. As Rav Huna explains, since he affixed the first fringes prematurely—before the garment had a tzitzis obligation—he didn’t fulfill the command of, “You shall make tzitzis on your garments,” which implies that the act of attaching the tzitzis to the garment must be an act of creating valid tzitzis.
The gemara questions the notion that attaching the tzitzis prematurely does not meet the standard of “making” the tzitzis from a ruling of R’ Zeira. R’ Zeira discusses the halachah in a case where someone attached a second set of tzitzis to a garment and then removed the old set. R’ Zeira rules that the tzitzis are kosher. This would appear to contradict Rav Huna’s ruling: since at the time of attachment the new set was superfluous, according to Rav Huna this should not be considered a proper “making” of the tzitzis!
Rava suggests a distinction to reconcile these two rulings. He points out that this act of adding another set of tzitzis was Biblically forbidden under “You shall not add to it,” which forbids us from adding onto the requisite number (e.g. four fringes) of any mitzvah in the Torah. Since the act of adding another set of tzitzis was a Torah violation it is an act that is completely null and void and thus from the halachah’s point of view, this person is considered to have made the tzitzis at the time when he restored the fringes to their proper number by removing the original fringes. Consequently, these tzitzis were properly made and are perfectly valid.
But the gemara rejects this distinction on grounds that it makes the unwarranted assumption that the person’s intention here was to flagrantly add to the number of tzitzis required by the Torah. It’s more reasonable to assume, R’ Pappa points out, that this person simply desired to replace the old tzitzis—he just chose to add the new tzitzis before removing the old ones. If so we can no longer view the adding of the new tzitzis as a halachically meaningless action; rather, he did clearly add these tzitzis at a premature stage, which means that R’ Zeira’s ruling that the tzitzis are kosher is truly at odds with Rav Huna’s position.