Difference between revisions of "Purpose of the Laws of Kashrut/2"

From AlHaTorah.org
Jump to navigation Jump to search
m
Line 6: Line 6:
 
<div class="overview">
 
<div class="overview">
 
<h2>Overview</h2>
 
<h2>Overview</h2>
Commentators debate whether the laws of Kashrut were instituted for their physical or spiritual benefits. Rashbam maintains that their purpose is purely utilitarian, and they serve to ensure the health of the nation. Akeidat Yitzchak vehemently disagrees that a commandment would be instituted for such mundane reasons, claiming that the laws must somehow elevate man. He, thus, asserts that Hashem forbade the eating of all predatory animals since ingesting such an animal can detrimentally affect the character of the consumer. Moreover, regardless of the nature of the forbidden foods, setting limits helps man to control his desires.&#160; Finally, a last approach suggests that the goal of the laws was to separate Israel from her neighbors. Having a unique diet distinguishes Israel from others, both minimizing contact and marking her as a "kingdom of priests."</div>
+
Commentators debate whether the laws of Kashrut were instituted for their physical or spiritual benefits. Rashbam maintains that their purpose is purely utilitarian, and they serve to ensure the health of the nation. Akeidat Yitzchak vehemently disagrees that a commandment would be instituted for such mundane reasons, claiming that the laws must somehow elevate man. He, thus, asserts that Hashem forbade the eating of all predatory animals since ingesting such an animal can detrimentally affect the character of the consumer. Moreover, regardless of the nature of the forbidden foods, setting limits helps man to control his desires.&#160; Finally, a last approach suggests that the goal of the laws is to separate Israel from her neighbors. Having a unique diet distinguishes Israel from others, both minimizing contact and marking her as a "kingdom of priests."</div>
  
 
<approaches>
 
<approaches>
Line 13: Line 13:
 
<p>The laws of Kashrut were instituted in order to protect the health of the members of the nation.</p>
 
<p>The laws of Kashrut were instituted in order to protect the health of the members of the nation.</p>
 
<mekorot><multilink><a href="RashbamVayikra11-3" data-aht="source">Rashbam</a><a href="RashbamVayikra11-3" data-aht="source">Vayikra 11:3</a><a href="R. Shemuel b. Meir (Rashbam)" data-aht="parshan">About R. Shemuel b. Meir</a></multilink>, <multilink><a href="RambamMorehNevukhim348" data-aht="source">Rambam Moreh Nevukhim</a><a href="RambamMorehNevukhim348" data-aht="source">3 48</a><a href="Rambam Moreh Nevukhim" data-aht="parshan">About Rambam Moreh Nevukhim</a></multilink>,&#160;<multilink><a href="RambanVayikra11-13" data-aht="source">Ramban</a><a href="RambanVayikra11-13" data-aht="source">Vayikra 11:13</a><a href="RambanDevarim14-3" data-aht="source">Devarim 14:3</a><a href="R. Moshe b. Nachman (Ramban, Nachmanides)" data-aht="parshan">About R. Moshe b. Nachman</a></multilink> #2,<fn>Ramban also points to the spiritual benefits of the laws, as discussed below.</fn> <multilink><a href="SeferHaChinukhCommandment73" data-aht="source">Sefer HaChinukh</a><a href="SeferHaChinukhCommandment73" data-aht="source">Sefer HaChinukh Commandment 73</a><a href="SeferHaChinukhCommandment148" data-aht="source">Sefer HaChinukh Commandment 148</a></multilink>,<fn>Sefer HaChinukh combines this approach with the one below which speaks of the spiritual benefits of observing the laws of Kashrut.&#160; He claims that the prohibited foods harm the body, but as the body is the platform for the soul, when the body is harmed, the soul is affected as well.</fn></mekorot>
 
<mekorot><multilink><a href="RashbamVayikra11-3" data-aht="source">Rashbam</a><a href="RashbamVayikra11-3" data-aht="source">Vayikra 11:3</a><a href="R. Shemuel b. Meir (Rashbam)" data-aht="parshan">About R. Shemuel b. Meir</a></multilink>, <multilink><a href="RambamMorehNevukhim348" data-aht="source">Rambam Moreh Nevukhim</a><a href="RambamMorehNevukhim348" data-aht="source">3 48</a><a href="Rambam Moreh Nevukhim" data-aht="parshan">About Rambam Moreh Nevukhim</a></multilink>,&#160;<multilink><a href="RambanVayikra11-13" data-aht="source">Ramban</a><a href="RambanVayikra11-13" data-aht="source">Vayikra 11:13</a><a href="RambanDevarim14-3" data-aht="source">Devarim 14:3</a><a href="R. Moshe b. Nachman (Ramban, Nachmanides)" data-aht="parshan">About R. Moshe b. Nachman</a></multilink> #2,<fn>Ramban also points to the spiritual benefits of the laws, as discussed below.</fn> <multilink><a href="SeferHaChinukhCommandment73" data-aht="source">Sefer HaChinukh</a><a href="SeferHaChinukhCommandment73" data-aht="source">Sefer HaChinukh Commandment 73</a><a href="SeferHaChinukhCommandment148" data-aht="source">Sefer HaChinukh Commandment 148</a></multilink>,<fn>Sefer HaChinukh combines this approach with the one below which speaks of the spiritual benefits of observing the laws of Kashrut.&#160; He claims that the prohibited foods harm the body, but as the body is the platform for the soul, when the body is harmed, the soul is affected as well.</fn></mekorot>
<point><b>Why these animals?</b> According to this approach, all the prohibited animals are unhealthy, while the permitted animals are not. Rambam notes that pigs are particularly unhygienic<fn>See <multilink><a href="BavliKiddushin49b" data-aht="source">Bavli Kiddushin</a><a href="BavliKiddushin49b" data-aht="source">Kiddushin 49b</a><a href="Talmud Bavli" data-aht="parshan">About the Bavli</a></multilink> which claims, "עשרה קבים נגעים ירדו לעולם ט׳ נטלו חזירים".</fn> and if they were permitted to be eaten they would introduce filth into the community, spreading disease.&#160;&#160;Bavli Shabbat 86b states that non-Jews "דאכלין שקצים ורמשים חביל גופייהו".</point>
+
<point><b>Why these animals?</b> According to this approach, all the prohibited animals are unhealthy, while the permitted animals are not. Rambam notes that pigs are particularly unhygienic,<fn>See <multilink><a href="BavliKiddushin49b" data-aht="source">Bavli Kiddushin</a><a href="BavliKiddushin49b" data-aht="source">Kiddushin 49b</a><a href="Talmud Bavli" data-aht="parshan">About the Bavli</a></multilink> which claims, "עשרה קבים נגעים ירדו לעולם ט׳ נטלו חזירים".</fn> and if they were permitted to be eaten, they would introduce filth into the community, spreading disease.&#160;&#160;Bavli Shabbat 86b states that non-Jews "דאכלין שקצים ורמשים חביל גופייהו".</point>
 
<point><b>The signs</b> – Rambam maintains that there is nothing intrinsic in the signs which provide a health benefit to the animal.&#160; They are only necessary so as to differentiate between the various animals.<fn>This is consistent with Rambam's tendency to view the details of laws as not necessarily having intrinsic significance.&#160;For instance, he suggests that there might not be any reason why a specific sacrifice necessitates a lamb and another a ram, or why one holiday is one day long and another lasts for seven days. See his discussion in <multilink><a href="RambamMorehNevukhim326" data-aht="source">Moreh Nevukhim 3:26</a><a href="RambamMorehNevukhim326" data-aht="source">3 26</a><a href="Rambam Moreh Nevukhim" data-aht="parshan">About Rambam Moreh Nevukhim</a></multilink>: "שכלל ה׳מצוה׳ יש לה סיבה בהכרח ומפני תועלת אחת צווה בה אבל חלקיה הם אשר נאמר בהם שהם למצוה לבד."</fn></point>
 
<point><b>The signs</b> – Rambam maintains that there is nothing intrinsic in the signs which provide a health benefit to the animal.&#160; They are only necessary so as to differentiate between the various animals.<fn>This is consistent with Rambam's tendency to view the details of laws as not necessarily having intrinsic significance.&#160;For instance, he suggests that there might not be any reason why a specific sacrifice necessitates a lamb and another a ram, or why one holiday is one day long and another lasts for seven days. See his discussion in <multilink><a href="RambamMorehNevukhim326" data-aht="source">Moreh Nevukhim 3:26</a><a href="RambamMorehNevukhim326" data-aht="source">3 26</a><a href="Rambam Moreh Nevukhim" data-aht="parshan">About Rambam Moreh Nevukhim</a></multilink>: "שכלל ה׳מצוה׳ יש לה סיבה בהכרח ומפני תועלת אחת צווה בה אבל חלקיה הם אשר נאמר בהם שהם למצוה לבד."</fn></point>
 
<point><b>Validity of health benefit claims</b> – Many commentators question the above claims:<br/>
 
<point><b>Validity of health benefit claims</b> – Many commentators question the above claims:<br/>
 
<ul>
 
<ul>
 
<li>Akeidat Yitzchak<fn>See also Abarbanel who follows him on this point.</fn> argues that this position is not supported by empirical evidence, as many non-Jews eat the forbidden foods with no unfortunate consequences.<fn>Shadal even notes that the camel's meat is known to be very healthy.</fn>&#160;</li>
 
<li>Akeidat Yitzchak<fn>See also Abarbanel who follows him on this point.</fn> argues that this position is not supported by empirical evidence, as many non-Jews eat the forbidden foods with no unfortunate consequences.<fn>Shadal even notes that the camel's meat is known to be very healthy.</fn>&#160;</li>
<li>Abarbanel further notes that if the Torah's goal was to keep the nation healthy, one would expect it to include a complete list of damaging foods, yet there are many other foods which are detrimental to the body that are not mentioned.</li>
+
<li>Abarbanel further notes that if the Torah's goal was to keep the nation healthy, one would expect it to include a complete list of damaging foods.&#160; Yet, there are many other foods which are detrimental to the body that are not mentioned.</li>
 
</ul>
 
</ul>
 
Sefer HaChinukh defends this position, claiming that Israel can trust Hashem to know better than any scientist which foods are healthy and which are not.</point>
 
Sefer HaChinukh defends this position, claiming that Israel can trust Hashem to know better than any scientist which foods are healthy and which are not.</point>
Line 24: Line 24:
 
<point><b>Why is the purpose not stated?</b> Sefer HaChinukh claims that had the health reasons been relayed, individuals would assume that they have enough knowledge to decide for themselves what is healthy and what is not, rather than relying on Hashem's list.&#160; R. D"Z Hoffmann argues against this logic, asserting that since people tend to want to observe commandments which are beneficial to them, including the reasoning behind the ordinance would have increased observance, not diminished it.<fn>As such, he brings the lack of an explicitly stated reason as a proof against this understanding of the commandment.</fn></point>
 
<point><b>Why is the purpose not stated?</b> Sefer HaChinukh claims that had the health reasons been relayed, individuals would assume that they have enough knowledge to decide for themselves what is healthy and what is not, rather than relying on Hashem's list.&#160; R. D"Z Hoffmann argues against this logic, asserting that since people tend to want to observe commandments which are beneficial to them, including the reasoning behind the ordinance would have increased observance, not diminished it.<fn>As such, he brings the lack of an explicitly stated reason as a proof against this understanding of the commandment.</fn></point>
 
<point><b>Context in Vayikra:&#160; laws of purity</b> – Though, at first glance, it is difficult to find a common denominator between this understanding of the laws of Kashrut and the other laws of impurity, it is possible that this approach might view all forms of impurity as related to disease.&#160; See, for example, Ralbag on <a href="Tzara'at" data-aht="page">Tzara'at</a>.</point>
 
<point><b>Context in Vayikra:&#160; laws of purity</b> – Though, at first glance, it is difficult to find a common denominator between this understanding of the laws of Kashrut and the other laws of impurity, it is possible that this approach might view all forms of impurity as related to disease.&#160; See, for example, Ralbag on <a href="Tzara'at" data-aht="page">Tzara'at</a>.</point>
<point><b>Context in Devarim: תועבות הגויים</b> – In Devarim, the laws of impure animals follow laws that relate to the abominations of other nations.&#160; If the commandment is health-related it is difficult to see how the two sets of laws are connected and why they appear together. This approach might suggest that actually the directives really are unrelated and no significance should be read into their juxtaposition.<fn>However, the fact that the unit opens by calling the prohibited foods an abomination ("לֹא תֹאכַל כׇּל תּוֹעֵבָה") would suggest that there is nonetheless some connection.</fn></point>
+
<point><b>Context in Devarim: תועבות הגויים</b> – In Devarim, the laws of impure animals follow laws that relate to the abominations of other nations.&#160; If the commandment is health-related it is difficult to see how the two sets of laws are connected and why they appear together. This approach might suggest that the directives really are unrelated, and no significance should be read into their juxtaposition.<fn>However, the fact that the unit opens by calling the prohibited foods an abomination ("לֹא תֹאכַל כׇּל תּוֹעֵבָה") would suggest that there is nonetheless some connection.</fn></point>
 
<point><b>"וִהְיִיתֶם קְדֹשִׁים"</b> – The conclusion of&#160;"וִהְיִיתֶם קְדֹשִׁים" (Vayikra 11:44-45) suggests that Kashrut laws enable the nation to become holy.&#160; However, if the purpose of the laws is simply utilitarian (good health), it is not clear why, of all laws, these should be said to promote "holiness".&#160; These sources could suggest that the verse is not related specifically to the laws of Kashrut, but to general observance of Hashem's ordinances.<fn>See <multilink><a href="RYosefKaraVayikra11-44" data-aht="source">R. Yosef Kara</a><a href="RYosefKaraVayikra11-44" data-aht="source">Vayikra 11:44</a><a href="R. Yosef Kara" data-aht="parshan">About R. Yosef Kara</a></multilink> who explains the verse this way.</fn></point>
 
<point><b>"וִהְיִיתֶם קְדֹשִׁים"</b> – The conclusion of&#160;"וִהְיִיתֶם קְדֹשִׁים" (Vayikra 11:44-45) suggests that Kashrut laws enable the nation to become holy.&#160; However, if the purpose of the laws is simply utilitarian (good health), it is not clear why, of all laws, these should be said to promote "holiness".&#160; These sources could suggest that the verse is not related specifically to the laws of Kashrut, but to general observance of Hashem's ordinances.<fn>See <multilink><a href="RYosefKaraVayikra11-44" data-aht="source">R. Yosef Kara</a><a href="RYosefKaraVayikra11-44" data-aht="source">Vayikra 11:44</a><a href="R. Yosef Kara" data-aht="parshan">About R. Yosef Kara</a></multilink> who explains the verse this way.</fn></point>
<point><b>Comparison to laws of other prohibited foods</b> – The Rambam explicitly writes that the same reasoning applies to the similar prohibitions of eating an unslaughtered animal (נבילה), a torn beast of prey (טריפה), and fat, pointing out that they are all difficult to digest.<fn>Rambam also notes that combining meat and milk results in heavy and filling food, not ideal for the best health.</fn>&#160; Sefer HaChinukh, following Ramban, also notes that the fact that the animal became a "טריפה" proves that the animal was sick and therefore had the potential to transmit its disease to any who eat of it.<fn>Despite these examples, these commentators are not consistent in explaining <b>all</b> prohibited foods in this manner. For instance,&#160;<multilink><a href="RashbamShemot23-19" data-aht="source">Rashbam</a><a href="RashbamShemot23-19" data-aht="source">Shemot 23:19</a><a href="R. Shemuel b. Meir (Rashbam)" data-aht="parshan">About R. Shemuel b. Meir</a></multilink> on Shemot 23:19 explains the prohibition of cooking a goat in its mother's milk to be related to eliminating gluttony and cruelty, while Rambam associates it with idolatrous practices.</fn></point>
+
<point><b>Comparison to laws of other prohibited foods</b> – The Rambam explicitly writes that the same reasoning applies to the similar prohibitions of eating an unslaughtered animal (נבילה), a torn beast of prey (טריפה), and fat, pointing out that they are all difficult to digest.<fn>Rambam also notes that combining meat and milk results in heavy and filling food, not ideal for the best health.</fn>&#160; Sefer HaChinukh, following Ramban, also notes that the fact that the animal became a "טריפה" proves that the animal was sick and has the potential to transmit disease to any who eat of it.<fn>Despite these examples, these commentators are not consistent in explaining <b>all</b> prohibited foods in this manner. For instance,&#160;<multilink><a href="RashbamShemot23-19" data-aht="source">Rashbam</a><a href="RashbamShemot23-19" data-aht="source">Shemot 23:19</a><a href="R. Shemuel b. Meir (Rashbam)" data-aht="parshan">About R. Shemuel b. Meir</a></multilink> on Shemot 23:19 explains the prohibition of cooking a goat in its mother's milk to be related to eliminating gluttony and cruelty, while Rambam associates it with idolatrous practices.</fn></point>
 
<point><b>Polemical motivations?</b> Rashbam prefaces his explanation of the laws of Kashrut by writing: "ולפי פשוטו של מקרא ותשובת המינים," suggesting that his words are a response to non-believers.&#160; M. Lockshin<fn>See his edition of Rashbam's commentary (Jerusalem, 2004) and his notes on Vayikra 13:3.</fn> explains that Christian claims that dietary restrictions were not necessary<fn>See, for instance, Matthew 15:10-11, "Listen and understand. What goes into someone’s mouth does not defile them, but what comes out of their mouth, that is what defiles them."</fn> led Rashbam to defend them and point to their utility.&#160; This might have also motivated him to offer an explanation that displays the laws' universal benefit (rather than one limited to Jews).</point>
 
<point><b>Polemical motivations?</b> Rashbam prefaces his explanation of the laws of Kashrut by writing: "ולפי פשוטו של מקרא ותשובת המינים," suggesting that his words are a response to non-believers.&#160; M. Lockshin<fn>See his edition of Rashbam's commentary (Jerusalem, 2004) and his notes on Vayikra 13:3.</fn> explains that Christian claims that dietary restrictions were not necessary<fn>See, for instance, Matthew 15:10-11, "Listen and understand. What goes into someone’s mouth does not defile them, but what comes out of their mouth, that is what defiles them."</fn> led Rashbam to defend them and point to their utility.&#160; This might have also motivated him to offer an explanation that displays the laws' universal benefit (rather than one limited to Jews).</point>
 
</category>
 
</category>

Version as of 10:27, 5 August 2018

Purpose of the Laws of Kashrut

Exegetical Approaches

This topic has not yet undergone editorial review

Overview

Commentators debate whether the laws of Kashrut were instituted for their physical or spiritual benefits. Rashbam maintains that their purpose is purely utilitarian, and they serve to ensure the health of the nation. Akeidat Yitzchak vehemently disagrees that a commandment would be instituted for such mundane reasons, claiming that the laws must somehow elevate man. He, thus, asserts that Hashem forbade the eating of all predatory animals since ingesting such an animal can detrimentally affect the character of the consumer. Moreover, regardless of the nature of the forbidden foods, setting limits helps man to control his desires.  Finally, a last approach suggests that the goal of the laws is to separate Israel from her neighbors. Having a unique diet distinguishes Israel from others, both minimizing contact and marking her as a "kingdom of priests."

Health Benefit

The laws of Kashrut were instituted in order to protect the health of the members of the nation.

Why these animals? According to this approach, all the prohibited animals are unhealthy, while the permitted animals are not. Rambam notes that pigs are particularly unhygienic,3 and if they were permitted to be eaten, they would introduce filth into the community, spreading disease.  Bavli Shabbat 86b states that non-Jews "דאכלין שקצים ורמשים חביל גופייהו".
The signs – Rambam maintains that there is nothing intrinsic in the signs which provide a health benefit to the animal.  They are only necessary so as to differentiate between the various animals.4
Validity of health benefit claims – Many commentators question the above claims:
  • Akeidat Yitzchak5 argues that this position is not supported by empirical evidence, as many non-Jews eat the forbidden foods with no unfortunate consequences.6 
  • Abarbanel further notes that if the Torah's goal was to keep the nation healthy, one would expect it to include a complete list of damaging foods.  Yet, there are many other foods which are detrimental to the body that are not mentioned.
Sefer HaChinukh defends this position, claiming that Israel can trust Hashem to know better than any scientist which foods are healthy and which are not.
Can laws be utilitarian in nature? Akeidat Yitzchak and Abarbanel further question this position, pointing out that the purpose of Torah is not to teach medicine but rather to instill good character and deeds.  As such, it does not make sense that the laws of Kashrut would have been instituted for their health advantages. These sources would argue that Akeidat Yitzchak's fundamental assumption,  that laws cannot be utilitarian in nature, is simply wrong. Rambam, for example, gives practical explanations for several commandments, including Shemittah and the incense altar.7
Why is the purpose not stated? Sefer HaChinukh claims that had the health reasons been relayed, individuals would assume that they have enough knowledge to decide for themselves what is healthy and what is not, rather than relying on Hashem's list.  R. D"Z Hoffmann argues against this logic, asserting that since people tend to want to observe commandments which are beneficial to them, including the reasoning behind the ordinance would have increased observance, not diminished it.8
Context in Vayikra:  laws of purity – Though, at first glance, it is difficult to find a common denominator between this understanding of the laws of Kashrut and the other laws of impurity, it is possible that this approach might view all forms of impurity as related to disease.  See, for example, Ralbag on Tzara'at.
Context in Devarim: תועבות הגויים – In Devarim, the laws of impure animals follow laws that relate to the abominations of other nations.  If the commandment is health-related it is difficult to see how the two sets of laws are connected and why they appear together. This approach might suggest that the directives really are unrelated, and no significance should be read into their juxtaposition.9
"וִהְיִיתֶם קְדֹשִׁים" – The conclusion of "וִהְיִיתֶם קְדֹשִׁים" (Vayikra 11:44-45) suggests that Kashrut laws enable the nation to become holy.  However, if the purpose of the laws is simply utilitarian (good health), it is not clear why, of all laws, these should be said to promote "holiness".  These sources could suggest that the verse is not related specifically to the laws of Kashrut, but to general observance of Hashem's ordinances.10
Comparison to laws of other prohibited foods – The Rambam explicitly writes that the same reasoning applies to the similar prohibitions of eating an unslaughtered animal (נבילה), a torn beast of prey (טריפה), and fat, pointing out that they are all difficult to digest.11  Sefer HaChinukh, following Ramban, also notes that the fact that the animal became a "טריפה" proves that the animal was sick and has the potential to transmit disease to any who eat of it.12
Polemical motivations? Rashbam prefaces his explanation of the laws of Kashrut by writing: "ולפי פשוטו של מקרא ותשובת המינים," suggesting that his words are a response to non-believers.  M. Lockshin13 explains that Christian claims that dietary restrictions were not necessary14 led Rashbam to defend them and point to their utility.  This might have also motivated him to offer an explanation that displays the laws' universal benefit (rather than one limited to Jews).

Spiritual Benefit

The prohibition helps man perfect his character and elevate his soul.  This approach subdivides regarding the specific benefit received and how this is achieved:

You Are What You Eat

Since what you eat affects who you are, Hashem forbade Israel from consuming animals with negative traits. The laws of Kashrut thereby aid to both purify the soul and prevent men from becoming cruel.

Why these animals? These sources offer several reasons why these particular animals were selected:
  • Invite cruelty - Almost all of the animals20 and birds21 which are forbidden are predatory.22 Since a person's character is developed by what they eat,23 Hashem prohibited these carnivores to ensure that humans don't similarly become beasts of prey.24
  • Defile the soul / intellect - Hashem further prohibited repulsive animals whose material make-up affects the soul and intellect negatively. Ramban and Ralbag25 explain that animals who are "עב החומר" (lit. of thick material) tarnish the soul / intellect, making it difficult to attain holiness and comprehend Hashem.26
  • Used for idolatrous rites – Abarbanel additionally suggests that the prohibited animals are eaten by idolaters as part of their worship of foreign gods.27 As such, Hashem distanced the practice from Israel.
The signs – The signs of the animals are indicative of their nature:28
  • "מַפְרֶסֶת פַּרְסָה וְשֹׁסַעַת שֶׁסַע"‎29‎ – Split hooves are signs of herbivorous animals.  Carnivores instead have claws used for killing their prey.
  • "מַעֲלַת גֵּרָה" – This, too, is a sign of an herbivore.  Since plants are not easy to digest, such animals regurgitate their food so as to chew it a second time.
  • "סְנַפִּיר וְקַשְׂקֶשֶׂת" – As many scaled fish are still carnivorous, the permitted status of such fish is somewhat inconsistent with this approach.30
Can laws be utilitarian in nature? Akeidat Yitzchak and Abarbanel attack utilitarian understandings of the dietary laws, claiming that the Torah's purpose is to perfect man's nature. As such, they claim that the restrictions must provide a spiritual benefit to the nation.
"וְלֹא תְטַמְּאוּ אֶת נַפְשֹׁתֵיכֶם" / "וִהְיִיתֶם קְדֹשִׁים" – Akeidat Yitzchak and Abarbanel31 assert that the verses use the language of holiness and purity rather than healthy / unhealthy because they speak of a spiritual state rather than a physical one.  Hence, too, the emphasis on the law's effects on the soul: "וְלֹא תְטַמְּאוּ אֶת נַפְשֹׁתֵיכֶם".
Context in Vayikra: laws of impurity – These sources offer two different explanations to understand the placement of the unit:
  • Sub-unit of impurity laws – R"Y Bekhor Shor and Seforno32 view the laws of Kashrut as a sub-unit of the other laws of purity and holiness discussed in the surrounding chapters.  R"Y Bekhor Shor asserts that all the laws delineate those who are not worthy of approaching Hashem due to their contaminated state. Since eating "detested" species defiles the soul, a person who does not abide by the laws of Kashrut has a status similar to that of other impure people.
  • Unit is a tangent – Ramban explains that the laws of Kashrut appear here only tangentially.  The main focus of the chapter is the ordinances dealing with the status of those who come in contact with impure animals33 (which are clearly related to the surrounding discussions of impurity), while the laws regarding Kashrut are only secondary.34 
Laws necessary only post-sin – Seforno includes Kashrut among a list of laws which he maintains were only introduced in the aftermath of the Sin of the Golden Calf. After the sin, Hashem initially no longer wanted His presence to reside among the nation at all, but when Moshe's prayers attained a compromise which allowed for the Mishkan, it was necessary that the people elevate their souls to be worthy of it.35  Thus, Hashem introduced the laws of Kashrut to purify the people (and the laws of emissions and a birthing mother to purify their seed).36
Context in Devarim: תועבות הגויים – Ramban points out that the verse states: "לֹא תֹאכַל כׇּל תּוֹעֵבָה" because impure animals are an abomination for the soul; thus, their placement right after a discussion of other "abominations" is fitting. According to Abarbanel, who associates the non-kosher animals with idolatrous rites, the juxtaposition of the two sets of laws is even more understandable.
Comparison to other prohibited foods – Other foods are similarly understood to be prohibited to ensure spiritual health:
  • The original prohibition to eat meat – Several commentators37 assume that before the flood, all meat was prohibited38 because its consumption has deleterious effects on man's moral fiber.39 After the flood Hashem made concessions to human nature, allowing them to eat meat, but nonetheless limited its consumption to the least harmful of species.
  • Prohibition of milk and meat – This approach could follow the Rambam who suggests that the practice of cooking a goat in its mother's milk has idolatrous roots and was thus forbidden.  Alternatively it could agree with R. Bachya who asserts that the combination of meat and milk fats muddles the heart and introduces coarseness into the soul.40 
  • Prohibition of blood – Sefer HaChinukh explains that eating the life-source of an animal tarnishes a person, and leads to cruelty.41

Limits Teach Self Control

The dietary laws limit the number of animals one can eat in order to train people to control their desires.

Why these animals and signs? These sources disagree regarding whether or not there is significance to the list of animals chosen and the signs given to identify them:
  • Significant – Philo notes that swine is considered to be the "nicest of all meats", and fish which lack scales are the "most delicate" of fish, suggesting that Hashem chose to prohibit the most desired of animals.  The signs are perhaps indicative of how palatable the food is.46
  • Insignificant – Alternatively, Shadal suggests that there is nothing inherent in the animals chosen to be prohibited47 and really it would not matter if others had been listed in their stead; the purpose was simply to pick a select few to be off-limits for consumption.48
"וִהְיִיתֶם קְדֹשִׁים" – R. Bachya maintains that being holy first and foremost entails controlling one's desires and curbing one's appetite.49 The root "קדש" means to separate,50 expressed here by abstaining from certain foods. Practicing abstinence and setting limits enables people to strengthen the rational mind so it can override one's natural sensual cravings and impulse to sin.51 Moreover, such limits make one constantly think of Hashem, instilling fear of Heaven and wariness from transgression.52
Why not prohibit all meat? Philo claims that Hashem looked to find  "a middle path," neither being overly strict in His restrictions, nor excessive in what He permits.
Context in Vayikra:  laws of purity – The laws of impurity as a whole serve a similar function, as they, too, set objects off-limits, restricting contact with defiled objects and prohibiting the defiled from entering certain areas.
Similar prohibitions
  • R. Bachya asserts that other laws, such as fast days and prohibited sexual relations, similarly serve to curb man's desires.53
  • Akeidat Yitzchak goes a step further to suggest that all laws whose reason is unclear (such as the prohibition to wear linen and wool together) need have no other purpose other than the fact that they restrict man.54 The very existence of guiding laws forces man to control himself and recognize that he is meant to live according to Hashem's desires and not his own.55

Separation

The laws of Kashrut are intended to distinguish and distance Israel from the other nations.

"וִהְיִיתֶם קְדֹשִׁים" – This phrase expresses the purpose of the mitzvah – that Israel should be separate from others, with a special relationship to Hashem. Vayikra 20:25-26 says even more explicitly: "וִהְיִיתֶם לִי קְדֹשִׁים כִּי קָדוֹשׁ אֲנִי י"י וָאַבְדִּל אֶתְכֶם מִן הָעַמִּים לִהְיוֹת לִי".
Context in Devarim – The introductory verses to the unit in Sefer Devarim similarly emphasize Israel's distinct status: "בְךָ בָּחַר י"י לִהְיוֹת לוֹ לְעַם סְגֻלָּה מִכֹּל הָעַמִּים", further supporting this reading of the purpose of the commandment.
Attaining priesthood – Shadal points out that in abiding by the laws of Kashrut, the nation elevates itself and becomes "a kingdom of priests". In other cultures, too, the priests had certain individual restrictions which distinguished them from laymen. Israel, being the priest among the nations, thus, does the same.
Relationship to other laws of impurity – If these laws are a means of transforming the whole nation into priests, the placement of the unit among other laws dealing with purity, holiness, and entry into the Mikdash, is understandable.57
How does Kashrut serve to separate? The very fact that Jews have a unique diet, not shared by their neighbors, marks them as different. In addition, from a practical perspective, the dietary restrictions make it more difficult to socialize and celebrate with Gentiles, as many aspects of people's interactions revolve around food.
Why these animals and signs?
  • No significance – According to Shadal, there is nothing intrinsic in the choice of animals or their signs which led to their being forbidden / permitted.  Any animals that would have been chosen could have achieved the same goal of differentiating the people.
  • Unworthy of priests – Alternatively, since the nation is a "kingdom of priests," it is possible that only those animals which are worthy of being sacrificed were also permitted to be eaten.58 This would explain the choice to refer to these animals as "pure" and impure" rather than "permitted" and "forbidden".59  The forbidden birds and fish, on the other hand, might instead be prohibited since "שֶׁקֶץ הֵם לָכֶם;" they are "detestable," and, thus, unworthy of those of higher stature.60