Zevachim 50: Verbal Analogies and Their Limitations

Some brief notes about today's daf:

• can a halacha based on a word analogy be used to teach a law based on a different word analogy?

• can a halacha be learned from a word analogy used to teach based on a gezeira shava, a word analogy where the exact word might be used in both?

• can a halacha be learned from a word analogy based on a kal vachomer, a word analogy "from light to heavy" used as English uses "even more so"

• can a halacha be learned from a word analogy used to teach based on a binyan av, a rule based on a verse (or verses) that is applied to all cases that are similar to the first verse?

The following is taken from steinsaltz.org:

All of these methods of analysis are among the midot she-haTorah nidreshet bahem – the hermeneutical principles established by the Sages and used to derive laws from the Torah. These specific examples are used as follows: 

Hekesh – is an analogy. When two cases are mentioned together in the same passage or in adjacent passages, we can assume that since they are juxtaposed, they are analogous. For this reason, legal inferences may be drawn by comparing the two cases. On rare occasions, such as in our case, the analogy may be stated explicitly in the Torah. 

Gezeira shava – is a verbal analogy. If the same word or phrase appears in two places in the Torah, we may infer on the basis of “verbal analogy” that the same law must apply in the other case, as well. 

Kal vaḥomer – is an a fortiori inference. This is a rule of logical argumentation by means of which a comparison is drawn between two cases, one lenient and the other stringent. Kal vaḥomer asserts that if the law is stringent in a case where we are usually lenient, then it will certainly be stringent in a more serious case; likewise, if the law is lenient in a case where we are usually not lenient, then it will certainly be lenient in a less serious case. 

Binyan av – is an interpretation based on paradigm. While there are different types of binyan av, the simplest form of binyan avfollows the logical pattern “just as we find in Case A that Law X applies, so too we may infer that in Case B, which is similar to Case A, law X should apply.”