where sfeikos span a spectrum - kashrus, bein ha'shemashos

The Netziv reads  לְהַבְדִּ֕יל בֵּ֥ין הַטָּמֵ֖א וּבֵ֣ין הַטָּהֹ֑ר וּבֵ֤ין הַֽחַיָּה֙ הַֽנֶּאֱכֶ֔לֶת וּבֵין֙ הַֽחַיָּ֔ה אֲשֶׁ֖ר לֹ֥א תֵאָכֵֽל (11:47) as a mitzvah to examine any case of safeik to determine whether the animal is kosher or not.  Even though sfeika d'oraysa according to the Rambam is l'kula on a d'oraysa level, that is only when it is impossible to resolve the safeik.  Here it is not only possible, but it is a mitzvah to resolve the safeik.  Meaning, the Torah does not want a person to simply label any safeik as tfeif with the goal of erring on the side of caution.  The Torah wants and commands a person to find out the truth.  Netziv writes:   וכשם שאסור להקל בספק הקרוב להחמיר. או שלא לברר איזה ספק ולנהוג בו היתר כך אסור להחמיר במקום שאפשר לברר היתרו    

The Netziv then makes an interesting comment on the language of the pasuk.  He notes that sometimes the Torah distinguishes 2 things by saying "bein X and Y" and sometimes it distinguishes, like in our pasuk, by saying something like "bein X u'bein Y," repeating the word "bein" twice.  When the word is repeated, it indicates that we are speaking about two things or two groups being compared that have points where they are unlike at all, but also have points where they are very similar and come close to overlapping, where the difference is very subtle.  Had the Torah said "bein ha'tamei la'tahor," it would mean that if you examine a case of safeik, you will be able to tell clearly whether it is tamei or tahor.  By saying "bein ha'tamei u'bein ha'tahor" the Torah is speaking about two different cases of safeik: the case of safeik which is similar to tahor animals, but there is still some doubt, and the case of safeik which seems similar to tamei animals, but there is still some doubt.  The Torah is telling us that there is a spectrum of safeik: one end is close to tahor, the other end is closer to tamei, and the middle is a blur.  The nafka mina is for onshim.  There is a more severe punishment for erring in a case of safeik close to the tamei end of the spectrum and less severe punishment for erring in a case on the end of the spectrum closer to tahor -- take a look at the Netziv for examples.

We have another example of the "bein...bein" distinction right in the first chapter of chumash: "Vayavdeil Elokim bein ha'or u'bein ha'choshech."  Bein ha'shemashos, twilight, is a safeik period between day and night.  The beginning of b"hs is closer to day, the end is closer to night, and the middle is blurry state where the two come come close to converging. 

The Netziv applies this chiddush to reading the Mishna we say every Friday night at the end of perek 2 of Shabbos: safeik chasheicha safeik aina chasheicha... where the Mishna tells us the laws of bein hashemashos.  Why does the Mishna need to say "safeik...safeik?"  Why not just say "safeik chasheicha or aina chasheicha?"  And why does the Mishna put "safeik chasheicha" first when the day chronologically moves from aina chasheicha towards chasheicha and not the other way around?  Netziv answers that the Mishna phrases itself this way because bein hashemashos as a spectrum of safeik, one end very close to day where there is only a slight "safeik chasheicha," the other end closer to night where there is only a slight "safeik aina chasheicha."

The Netziv's proof from that Mishna is noteworthy because of the pshat the Netziv does not learn.  The MG"A (342) raises the following question: does the principle in the Mishna that there was no gezeira on shvusin derabbanan apply only to bein hashemashos Friday night, or does it also apply to bein hashemashos of Shabbos, Sat night, as well?  Perhaps on Friday the assumption is that the day is chol until proven otherwise, and therefore the Mishna has certain leniencies for bein hashemashos, but maybe once Shabbos starts the day has a chazakah of kedusha until proven otherwise, and therefore one must be strict during bein hashemashos of Sat night until certain nightfall?  Many Achronim kick this safeik around.  Is it possible for there to be a chazakah on a unit of time when time is always changing?  See Ohr Sameiach here.  R' Akiva Eiger on that Mishna in Shabbos quotes a "davar nechmad" from the Tos Chadashim.  The reason the Mishna uses the word "safeik" twice (the Netziv's question) and the reason it puts the safeik chasheicha first is because it is speaking about two different bein ha'shemashos periods -- 1) the bein hashemashos of Friday night, which has a chezkas chol and our safeik is whether it is chasheicha and therefore Shabbos, and 2) the bein ha'shemashos of Sat night, which has a chezkas kodesh, and our safeik is whether aina chasheicha, whether that status has changed and we may be lenient because it is chol.  The upshot of the Mishna is that the same leniencies apply to both of these cases, both the bein hashemashos of Fri night and the bein has"s of Sat night.

Take your pick of the Netziv or RAK"E, either way, next time you read this Mishna, it will be that much more meaningful.