[Avodah] Apikores?

[Marty Bluke]

R' Zev Sero wrote:
<Because now we know better.  Many rishonim lived before the discovery
> of the Zohar, and all lived before the AriZal and the Baal Shem Tov,
> so they were missing information.  The AriZal was taught by Eliyahu
> Hanavi, and the Baal Shem Tov by Achiyah Hashiloni, and therefore knew
> things that had been completely forgotten in previous generations.

There is a famous statement of the Chazon Ish that we don't rely on
manuscripts of Rishonim to overturn psikei halacha. In other words,
even if we know for sure that the psak is based on an erroneous girsa
it doesn't matter, that version was accepted by the mesora. The
statement above about how we now know better completely contradicts
this Chazon Ish.