That there is no way to kasher an earthenware utensil is a famous principle throughout the Talmud, both in the areas of kashrut and ritual purity. But there are tantalizing hints to the contrary in some rabbinic writings. There is a reference in RAMBAM (and some others) that "clay cannot be kashered, unless it is returned to the kiln" and, speaking of baking of matzah for Passover, which was often done on a clay surface, we are told by RAMBAM, that, if the clay surface had been used to bake bread during the year, "it must be covered with burning coals" in order to be used for baking matzah. So, the rule may not be so hard and fast. A great seventeenth century rabbi, Rabbi Tzvi Ashkenazi (generally known a Chacham Tzvi, "Chacham" (Wise Man)being the usual Sepharadic title for a rabbi.. Although an Ashkenazi by birth, he adopted Sepharadic ways. A very wise man indeed), held a minority opinion that compared all utensils to the case discussed in the Talmud of wooden barrels that had held non kosher wine, needed no kashering after twelve months, as it is impossible that the taste of wine would last that long. Chacham Tzvi opined that this idea would work for everything, even earthenware. This opinion, however, was not widely accepted. Another view was that kashering earthenware is impossible with mere boiling (hag'alah), but boiling three times, would do the trick. This, too, was little accepted. In the twentieth century, Rabbi Moshe Feinstein wrote a responsum, that expensive china, or a set that had great sentimental value, could be kashered by allowing it to sit unused for a year, and then plunging the utensils three times into boiling water, thus combining the two previously noted opinions. This was widely accepted, with some adding that we can include the doubt if our well fired china really has the same laws as rough earthenware. (I have already mentioned that some regard glazed china as glass, and therefore with no need of kashering). This represents a most interesting approach.Several unaccepted views, when taken together, become acceptable. This is known as _"tziruf de'ot" (combining opinions). Those who accept this approach compare it to the well established Talmudic principle of "Sfek Sfeka" (double doubt). For instance, may I drink a cup of coffee in the home of someone who doesn't keep kosher? The issue is that the coffee may have been made in a pot that was recently used for non kosher. But I have a double doubt. First, was it made in a pot that had been used for non kosher within the last twenty four hours (after which it would be irrelevant)? Secondly, perhaps, even if it had been used within twenty four hours, it may have been with a food that does not taste good with coffee, thereby being considered as imparting a bad taste, which does not make anything else non kosher. The problem may be seen as similar to tziruf de'ot. Two unknowns come together, and the potential problem may be ignored. This approach is very widely accepted. However, the Vilna Gaon disagreed sharply. A single opinion in halachah, he argued, that has been rejected by virtually all other opinions, does not constitute a "doubt". Having two such non accepted opinions would still be zero plus zero equals zero. In practice, the view of tziruf is widely used, but the view of the Vilna Gaon causes many to hesitate.(Why not simply ask the host? The fact that he doesn't himself keep kosher, would render his answer suspect). A similar consideration exists in many areas of halachah. In my next post, I'll go into the realities of a kosher kitchen. I will attempt to give equal weight to all positions, but will not hesitate to say what I actually do at home.