Purpose of the Laws of Kashrut

Introduction

An Inexplicable Law

Vayikra 11 and Devarim 14 elaborate upon the dietary laws, dictating which foods are permitted and prohibited from consumption. The reasoning behind these restrictions is not stated explicitly and is not self-evident. As opposed to many laws instituted to ensure justice, improve man's character, commemorate a historical event, or connect man to Hashem, it is not clear what purpose the laws of Kashrut serve. Why does Hashem care which foods one eats or refrains from eating? Does consuming one type of animal or another make someone a better or worse person?

Significance of the Signs

The Torah provides signs to determine whether a food is permitted or prohibited. Kosher animals must both chew their cud and have split hooves, while fish must have fins and scales. Winged swarming insects (שֶׁרֶץ הָעוֹף) which move on four legs are prohibited, while those with jointed legs, "made to leap," are permitted. Swarms of the earth (שֶׁרֶץ הָאָרֶץ), in contrast, are all prohibited. Finally, the forbidden birds are simply listed by name.

Importance of the signs – Is their any significance to the signs given? Why should it matter whether or not an animal chews its cud or what type of hoof it has? Are fish with scales and fins intrinsically different from those without? What, if any, is the common denominator that unites all the animals which contain these signs?
Vayikra vs. Devarim – Why does Sefer Vayikra suffice with providing the signs of kosher animals, while Sefer Devarim also identifies them by name?
Sign vs. list – Why, in both Vayikra and Devarim, are birds listed by name without the Torah providing any criteria?
Birds vs. animals, forbidden vs. permitted – Why does the Torah in both Vayikra and Devarim opt to list the birds which are forbidden, while, when speaking of animals, Devarim lists the permitted ones?

Relationship to Context

The context of the dietary laws in Sefer Vayikra is the unit of laws dealing with impurity (including that caused by a corpse, tzara'at, bodily discharges, and child bearing), while the context in Devarim is a discussion of the abominations of foreign nations. How is Kashrut related to either of these? Why are foods designated as "pure" and "impure"? How does their status relate to the status of other "pure" or "impure" objects? In Devarim, the unit opens with the command, "לֹא תֹאכַל כׇּל תּוֹעֵבָה". What about the prohibited foods make them an abomination? Is there some foreign practice that is being opposed through the restrictions?

Additional Questions

"וִהְיִיתֶם קְדֹשִׁים" – In both Vayikra and Devarim,¹ the dietary laws are explicitly connected to the nation's holy status. What about these laws engenders holiness?
"טָמֵא הוּא לָכֶם" vs. "שֶׁקֶץ הוּא לָכֶם"– Regarding the prohibited animals, Hashem says: "טָמֵא הוּא לָכֶם". In contrast, when referring to the birds and fish, He states, "שֶׁקֶץ הוּא לָכֶם." Is there any significance to this distinction? Why is one group "impure" and the other "detestable"?
Relationship to other prohibitions – How are the laws of Kashrut discussed here related to other food prohibitions, such as not eating blood, fat, milk and meat mixtures, or one's first fruits? Are the reasons for each of the prohibitions distinct, or is there one common explanation that can be given for all?