You are probably intrigued. Why would anyone suggest that Kosher is not biblical? Leviticus 11 and Deuteronomy 14 articulates what should be eaten and what should not be eaten by Israelites without ambiguity. However, the terminology of Kosher vs. Unkosher is indeed not biblical. It does not appear in the Bible. Torah uses the terms טָהוֹר (tahor) “clean” and טָמֵא (tameh) “unclean”. By bringing non-biblical terminology into our modern conversations about ancient Jewish texts we bring a lot of confusion.
לְהַבְדִּיל בֵּין הַטָּמֵא וּבֵין הַטָּהֹר וּבֵין הַחַיָּה הַנֶּאֱכֶלֶת וּבֵין הַחַיָּה אֲשֶׁר לֹא תֵאָכֵל
“make a distinction between the unclean and the clean, and between the edible creature and the creature which is not to be eaten” (Lev 11:47).
Let me put it this way. Moses had no idea what Kosher is, because that concept and terminology did not yet exist in his day. It appeared much later in history. Using specific words and terms anachronistically we imbue the ancient texts with meanings they could not have had. How would you feel if someone wrote in a biblical commentary that Moses took out his iPhone and sent Aaron an SMS? You would not accept that a serious commentary. But biblical commentaries use the term Kosher to explain the specifics of ancient texts all the time and no one feels that anything is out of place. Perhaps the majority of people simply do not know what Kosher actually means.
What is Kosher?
The word Kosher comes from Hebrew כָּשֵׁר (kasher) which means “fit” or “proper”. This term derives not from the Bible but from post-biblical rabbinic theology. Conversely, non-kosher food is called Treif comes from Hebrew טְרֵפָה (terefah) which means “torn” describing an animal not slaughtered, but rather attached by a predator (Ex 22:30). While Torah describes animals as either clean or unclean, over millennia Jewish tradition developed an idea of “fitness of food” called כַּשְׁרוּת (kashrut). And while the laws of Kashrut are concerned with whether the animal fits into the clean or unclean category, that is not what determines whether the animal is Kosher. In other words, based on the Jewish law developed by the rabbis centuries after the Bible a biblically clean animal can still be non-Kosher. And the reason is simple. Kashrut is a legal category that relates primarily to the “method of slaughter” שְׁחִיטָה (shechitah) not the origin of the meat. The clean status of an animal is an assumed prerequisite. A clean animal slaughtered improperly is actually non-kosher according to the established tradition.
In order for the meat to be kosher, a proper slaughter is done with חַלָּף (chalaf) a very specific knife. Proper slaughter is concerned with the absence of blood (Gen 9:4, Lev 17:10–14, Deut 12:23–24) because it is expressly forbidden. But another major concern of kosher slaughter is the minimized suffering of the animal. The animal must be killed by a single cut across the throat. The cut must be of precise depth, in a specific area, simultaneously severing arteries, veins, nerves, trachea, and the esophagus. The animal dies instantly without suffering as all blood leaves the body naturally. These are the requirements that determine whether the meat is kosher or not.
You may be familiar with the term Glatt Kosher as well. This is yet another level of כַּשְׁרוּת (kashrut) that emerged more recently. It has to do with the internal organs of the animal. In order for meat to be labeled Glatt Kosher the internal organs must be inspected and deemed to be healthy. Just recently the Conservative Synagogue instituted a special certification called Magen Tzedek (shield of justice) to reflect the ethical aspects of kashrut and eco-kashrut concerns, down to the details of how the animals are raised (free-range vs. confined) and what they are fed. Today kashrut is expanded to non-meat products as well, to dairy, to vegitables, to toothpaste and detergents. As a category, Kashrut is complicated and is well beyond the instructions about cleft hooves in Torah.
While the Bible implies proper slaughter and absence of blood in the meat which is of clean origin and acceptable for consumption, the idea of כַּשְׁרוּת (kashrut) takes it to a whole different level, adding a long list of post-biblical innovations and requirements. So did Moses prescribe Israelites to eat Kosher? Or did he say to simply not to eat the meat of animals which are unclean, that which contains blood, died of natural causes, or was torn up by the predators? Perhaps through understanding the criteria the laws of Kashrut the difference between the terms “clean” and “kosher” is now more obvious. Characterizing meat as kosher or non-kosher in the biblical context is simply anachronistic and leads to confusion because the term is uniquely post-biblical.