I found a shiur given by R' David Fink rather enlightening and decided to share it hear. Nothing that follows is my own idea, only Rav Fink's. The original shiur can be heard here. As I only heard the shiur online I do not have any source notes unless Rav Fink said them. What happens when Kabbala and Halacha tell you to do two different things?
The Tur: Put on Teffilin shel Yad and Barech (l'haniach tefillin), then shel Rosh and make a second Beracha (al mitzvat tefillin).
R' Yosef Karo not only wrote the Beit Yosef and the Shulchan Aruch but was also a noted Kabbalist. He lived in Sfat during the time of the AriZal - in fact, he was his neighbor - and is the author of the Magid Meisharim. This work is a compilation of statements made by R' Karo while in a trance and a Magid spoke through R' Karo. There are times that the Magid and the R' Karo disagreed with each other. Of couse, R' Karo poskens in the Beit Yosef against the Magid. R' Yaakov Emden assumes this because R' Karo was a greater talmid chacham than the magid.
Rav Fink has heard of authors of fiction expressing similar methods. They go into a trance and the characters in the book speak to them and they authors write down the dialogue as they hear it in their minds. Unfortunately this gift is never given to writers of non-fiction. These authors have to work out their solutions rationally unlike the fiction authors that just let it flow.
The halachic R' Karo depended on his reason when writing the Shulchan Aruch, the mystical R' Karo reported his mystical periods in the Magid Meisharim. Whenever there is tension for R' Karo halacha is in accord with the rational reasoning in the Beit Yosef as poskened in the Shulchan Aruch.
Back to the Berachot of Tefillin:
Sefer HaAgur: I found in the Zohar from a saying of Rashbi - a single beracha is to be said on both tefillin together. The teffilin shel rosh on the head correspond to Zachor and teffilin shel yad next to the heart correspond to Shamor. Just as we say Shamor and Zachor were said together at Matan Torah a single beracha covers both tefillin. One should not wait between the two tefillin, one should do both without a hefshek. I am amazed that these great Rabbanim disagree with Rashbi in the Zohar, if the Poskim knew what was said in the Zohar, why did they disagree with it? In any case, the minhag is to make two beracha, but the right thing to do is to make one beracha.
R' Karo: I don't know why the Sefer HaAgur was mystified on this question. There are plenty of other examples between the gemara and the zohar, why is it this one that he's so interested in? In every case the poskim follow the gemara and never the zohar. Even if the poskim knew the zohar they wouldn't care - the reason the poskim say to make two berachot is because that's what it says in the Gemara. All the more so, in the days of the Reshonim the Sefer HaZohar was not yet known. It was transmitted it Rebbe to Talmid for generations and only surfaced published much later. Furthermore, the passage in the Zohar (quoted by the Sefer HaAgur) does not necessarily mean only to make one beracha for both tefillin. What it might mean is that the first beracha applies to both teffilin and therefore one should not interrupt between them, the teffilin shel rosh needs its own beracha. Bottom line - two berachot on Tefillin regardless of what the Zohar says.
We see here one clear example where we follow the Gemara and the Poskim regardless of the Zohar.
The Magen Avraham was the first of the great poskim to systematically apply kabbalistic sources in his halachic discussion. Previous to him people related to the Zohar as a body of matterial that explained to us the inner workings of Torah, the world, and the universe we live him. A philosophical insight into the world. He was therefore bothered between the tension between the Zohar and the Halachic material. He quoted the the Kenesset HaGedola: wherever theres a conflict between the kabbala and the halacha - the halacha is always in accordance with the poskim. He seems to be referring to a situation where all the poskim are on one side and the zohar is on the other side. If the kabbalists are stricter than what is required by the poskim we can be machmir like the kabbalists. any issue that is not mentioned in the poskim - no source in the gemara but does in the zohar - we have no authority to impose the practice upon the people. Only halacha can be forced upon the people, we can try to convince people to follow the kabbalistic method but that's it.
Sometimes people asked R' Moshe Feinstein what is the meaning or reason why so and so poskend this way found in other places. Someone asked R' Feinstein (found in the Iggrot Moshe) why did the Mishna Berurah posken that one who stays awake all night without sleep that he does not make the berachot Bircat haTorah etc.. Whenever there is a machloket amongst poskim and the weight of the Zohar and Kabbalists determine the outcome. In this case the Mishna Berurah should have followed the AriZal to make the beracha. So why did he reject this position? Answer: It's obvious that the idea that the Kabbalists always prevail wherever there is a machloket amongst the poskim that idea only pertains to material in the zohar itself - that prevails. Why? That material comes from the time of the Mishnah. But the works of the later Kabbalists - the AriZal and others - does not have the same weight of the Zoharic literature. Therefore one can poskin the AriZal just like one can poskin against one other posek.
Rav Fink finds it mysterious: The Iggrot Moshe speaks with a very clear voice. He never applies this above rule not even once.
The Chacham Zvi (who was a great Kabbalist in addition to being a noted Posek) when speaking about the Machloket about how one should position his bed (Kabbalists Head West / Feet East vs. Poskim Head North / Feet South) says in a situation where the Zohar is opposed to the Gemara and Poskim - we never abandon the poskim in favor of the position of the Zohar. When in comes to Halacha we ignore the Zohar and rely on the Poskim. However, in a situation where the Poskim are divided it is correct (note: he does say must) to follow the Kabbala.
His son, R' Yaakov Emden, even though he denied the antiquity of the zohar in Mitpachat Sefarim, was a major Kabbalist. I remember that my father zt"l lived across the street from the non-Jewish orphanage; his bed was oriented like the mekubalim say and not like the poskim. He himself wrote one should follow the poskim and not the kabbalah, but I saw in practice he did the opposite from what he wrote. In order for there to be a machloket people need to be in each others presence, it is improper to say two people who are unaware of each others opinion it is not proper to call this a machloket. Did the poskim know the words of the Zohar becasue it was being transmitted secretly and these poskim are outside of the chain of tradition. Perhaps they would have changed their mind had they known. We should not be concerned that we reject mystical ideas in Halacha - elu v'elu divrei elokim chaim. [R' Emden rejected its antiquity not its significance]. The purpose of the Zohar is not to tell us what to do or not to do, but to explain to us the inner workings of the universe. In a case where the words of the Talmud can be understood many different ways the commentaries have their back to the wall and cannot explain the words of the Talmud - in these cases they didn't know the words of the Zohar - we see a different understanding of things. It's not that the Zohar has a different idea it's that the Zohar can be used to explain the gemara and if the two can be brought into accord with each other then we should do it. In the end we are poskining like the Gemara.
How does this come down in the more recent poskim?
The Munkatcher Rav (R' Elazar Shapira) - a noted posek and mekubal - it's important to bear in mind the difference between nigleh and nistar (revealed and secret wisdom). When I study the Zohar and words of the great Kabbalists I think of myself as learning nigleh - revealed wisdom. When I study Gemara, the Rambam, the Tur, and the Shulchan Aruch I think of myself as learning nistar - the secret wisdom of Torah. The works of the kabbalists talk about Olam HaSefirot they say they talk about the mystical reality of Sefirot and they are. The Halchic literature does not say they are talking about the mystical reality but indeed they are this is why I call them Nistar - hidden.
The Shulchan Aruch HaRav - whenever there is a disagreement between the kabbalits and the poskim - you should posken like the gemara and the poskim. Make two berachot on tefillin. The Baal HaTanya accepts the position of the Magen Avraham , we can require people to follow the gemara and no the Zohar. Halacha and Halachic sources always prevail over the Zohar and Kabbalistic sources.
Rav Fink notes that Chabad Chassidim do not follow this position. In every conflict between the Gemara and the Zohar they follow the Zohar instead of the ruling of the Baal HaTanya and make one beracha on tefilin. The Shaar HaKollel - R' Avram David Livat - I heard from a Chasid before he died that the Baal HaTanya had been asked about this question. Our minhag is to follow the Mekubalim instead of the poskim. Why then did you write in Shulchan Aruch HaRav to follow the poskim? I only wrote that because the poskim write to follow the poskim, but the mekubalim all write to follow the Zohar. It cannot be that the mekubalim would not follow the gemara and therefore the question doesn't make sense. This is what I heard from that Chasid before he died.
This is a tradition starting three generations after the Baal HaTanya. This is the reason the Baal HaTanya started to write a second edition of the Shulchan Aruch HaRav but only got a few pages in where he surely would have poskened like the mekubalim against the poskim.
Rav Fink: We find many stories (folk literature) that a major posek changed his mind on their deathbed. These stories are possibly true and it surely does happen and I doubt that it happens every time it is reported.
The traditions of the Gra weigh heavily on the Aruch HaShulchan and writes: When there is a machloket between the Zohar and the Poskim we of course follow the Poskim. It is correct to be machmir like the Zohar when they are machmir. One cannot require one to follow the Zohar. I have a tradition (from the Gra) that is impossible that there is a true conflict between the Gemara and the Zohar unless of course there are multiple opinions in the Gemara and the Zohar is holding like one opinion there. People have an incorrect understanding of the Zohar if they think there is a machloket between them
