Minimum Size Requirement for a Ketem Stain
The previous shiur discussed the requirement of hargasha to confer tumat nidda de-oraita. However, in the absence of hargasha, the rabbis decreed tuma on any blood, thus establishing the idea of tuma imparted by a ketem, a bloodstain. The Chakhamim did impose a condition: only blood which covers an area equal to the size of a geris (a certain species of bean) imparts tuma de-rabbanan. Less than this measurement of blood can be ascribed to alternate sources, primarily common household lice, the blood of which may have stained the clothing in question.
In fact, the question of attributing ketem blood to lice is the subject of a three-way machaloket amongst the Tana'im (Nidda 58b). Rabban Shimon ben Gamli'el only allows this in instances in which a woman has actively killed lice, thus increasing the likelihood of louse-blood creating a stain. The Chakhamim disagree, permitting any woman to attribute ANY amount of blood to lice. Ultimately the Gemara settles upon the compromise position of Rabbi Chanina ben Antigenos, who allows any woman to ascribe a stain to lice, but only if the stain covers an area less than the size of a geris.
How are we to understand this limitation? Did the rabbis allow "presumed attribution" since the entire prohibition is de-rabbanan from the beginning? As stated earlier (and in opposition to Rabban Shimon ben Gamli'el's stance) even a woman who has no known contact with lice may still rely upon the possibility of stains coming from their blood. Being that the issur is only mi-derabban even far-fetched attributions are reasons for leniency. Alternatively, perhaps the takkana become objectified? Based upon the mere chance of louse blood complicating niddut and allowing inaccurate appraisals, the rabbis officially determine that less than a geris's area of ketem blood will not halakhically confer tumat ketem - even INDEPENDENT of possible attribution to lice.
Of course, the most obvious consequence of this question surrounds the discovery of a geris of blood knowing that blood did indeed issue from the woman. Would we confer tuma in this case, disallowing the theoretical attribution to lice, or would we claim that this minimal measurement can never convey tuma? This issue is debated between the Kereiti and the Minchat Ya'akov, with the latter position maintaining that no nidda status is created and the former position affirming it. Presumably, they each view the geris requirement in dramatically different ways.
Yet another question would pertain to a woman who has knowingly killed many lice and notices a proportionate amount of blood. Can she 'stretch' the allowance to sizes beyond a geris claiming that "x minus a geris" comes from lice she has consciously squashed, while the final geris may stem from unknown lice? Just as a woman who has no known contact with lice may ascribe a geris to potential lice, so may this woman attribute "x plus a geris" with the "x" representing the number of lice she has killed. This indeed is the position of Tosafot in Nidda (58b); they seem to view the entire geris condition as based upon a theoretical attribution. By contrast, the Rosh (Nidda 8:60) claims that a geris is always tamei (presumably just as a geris is always tahor). It appears as if the Rosh sees ketem size as objectively defined, with less than a geris NEVER conveying tuma and a geris ALWAYS conveying tuma, regardless of subjective circumstances.
Conversely, we must consider stains of certain types of blood which are not ascribable to lice but are consistent with dam nidda. The Ra'avad, in his seminal work on the laws of niddut, Ba'alei Ha-nefesh, claims that a blackish bloodstain creates tuma even if its area is less than that of a geris. Since most lice do not possess this color of blood, it cannot be attributed to them. He seems to be operating upon the premise of Tosafot that the leniency is based upon possible attribution; where this attribution is empirically unlikely, even smaller stains will confer tuma. If the Rosh is correct, and no tuma was ever legislated for a geris, would we be lenient with blackish blood as well? Or would we claim that the legislation and subsequent objectification of a geris only evolved under conditions in which the blood THEORETICALLY could be imputed to lice? If we take the latter approach, blackish blood, which is clearly not louse-blood, was never limited by issues of size.
Earlier, we mentioned a machaloket between Acharonim regarding blood which clearly comes from the woman but is a geris. Traces of this issue can already be detected in a very interesting comment of the Rambam (Hilkhot Issurei Bia 9:6), who claims that a ketem found upon a woman's body does not require a geris for tuma; only ketamim upon clothing require this size. Apparently the Rambam felt that geris is only acceptable because we presume it to come from lice. If the blood is found upon a body, the likely presumption suggests that it is dam nidda even if the size is geris. The Ra'avad and many other Rishonim dispute this opinion of the Rambam, and perhaps they believe that the takkana was objectified and geris can NEVER convey tuma even if it seems likely that it was derived from a woman's body.
We see yet another interesting manifestation of the objectification of the takkana in an interesting statement of the Rama. In Ch. 185, he claims that the first three days of the seven clean days (zayin nekiyim) that a nidda counts possess a special status. If she discovers a bloodstain covering an area larger than that of a geris during this time – even a ketem which can normally be attributed to activities which may stain a woman or her clothing this blood would still disrupt her count. These first three days demand a higher standard, brooking no bloodstain whatsoever, even the type which can normally be ascribed to other activities. Thus, there are two different scales for blood which may have stained a woman from an external source: during normal periods it may be easily ascribed to potential environmental factors; during the counting of the first three of the seven clean days, however, a higher level obtains and Halakha permits no attribution to outside causes. However, if the ketem covers an area smaller than that of a geris, it does not disrupt the count days – even if detected during the first three days. It seems pretty clear from the Rama's statements that the geris measurement is about more than attribution to louse-blood, since during the first three days we do not look for outside sources in order to maintain purity. Evidently, less than a geris's area of ketem blood is just not considered dam nidda and does not disrupt the process of counting seven clean days.
A final issue to be considered concerns an intriguing halakha developed by the Ra'avad. Based upon a gemara in Nidda (58b) which suggests that the measurement of a geris may allow certain unique leniencies, the Ra'avad claims that if a larger geris (bean) were to be discovered, the allowable measurement of blood would similarly increase. This seems to indicate that the measurement of geris has been objectified; less than a geris cannot create nidda status since the rabbis never legislated against it from the start. Conceivably, if larger gerisim are found or bred, the allowable size would be redefined. If the geris measurement was cited by the rabbis simply to quantify the amount of blood one may ascribe to lice, we would question the Ra'avad's expansion. To be sure, the Taz does claim that if the size of a geris were to increase, we may assume that larger lice have also evolved, and hence larger amounts of blood may be imputed to them. However, the more direct manner of understanding the Ra'avad's view clearly indicates that the objective measurement of a geris no longer depends upon the presence of lice and their potential to explain bloodstains, supporting a new understanding of the nature of this takkana.