Kelal U-perat and Perat U-kelal (כלל ופרט ופרט וכלל)
The rules of "Kelal u-perat" and "perat u-kelal" ("General and particular, particular and general") is a limitation of the general by the particular and vice versa. According to rabbi Ishmael, this principle has eight special applications, and thus includes eight separate rules in his scheme (Nos. 4-11). This method of limitation is one of the main points of difference between Ishmael and Akiva. According to the former, who follows his teacher rabbi Nehunya ben HaKanah, the particular is only an elucidation of the preceding general expression, so that the latter includes only what is contained in the particular (כלל ופרט אין בכלל אלא מה שבפרט). But if still another general follows the particular, the two general expressions are defined by the intermediate particular, so that the law applies only to what is like the particular (כלל ופרט וכלל אי אתה מרבה אלא כעין הפרט). Akiva, on the contrary, applies the rule of increase and decrease (רבוי ומיעוט) which had been taught him by his teacher Nahum of Gimzo. According to this principle, the general followed by a particular subsumes everything which is like the particular (Sanhedrin 45b, 46a). If, however, another general term follows the particular, the former subsumes also what is not similar to the latter. The two general terms are decreased in only one respect by the intermediate particular (רבוי ומיעוט ורבוי ריבה הכל ומאי מיעט דבר אחר ; Shebu. 26a; comp. also Rashi on Sanhedrin l.c.).
The difference between kelal u-perat u-kelal (כלל ופרט וכלל) and ribbui u-miyut u-ribbui (רבוי ומיעוט ורבוי) is exemplified in the following example: Exodus 25:31 states ועשית מנרת זהב טהור מקשה תיעשה המנורה, "You shall make a Menorah of pure gold, hammered out shall the Menorah be made." The repetitive fashion of the statement can be explained by the kelal u-perat u-kelal or the ribbui u-miyut u-ribbui.
Whichever method of deduction is employed, the word ועשית ("You shall make") is an objective generalization, the words מנרת זהב ("pure gold") are an objective specification and the word תיעשה (shall be made") is again an objective generalization. The rule of kelal u-perat u-kelal works to teach that anything similar to the specification is deemed appropriate, while the rule of ribbui u-miyut u-ribbui is more inclusive, allowing everything except the thing most dissimilar to the specification.
Thus, Rashi's commentary in Rosh Hashanah 24b asserts that, according to the former method of learning this verse, the Menorah could, when necessary, be constructed of any metal (deemed in the same category of and thus similar to gold), whereas use of the latter method of learning would allow the Menorah to be constructed of anything but clay (deemed the material most dissimilar to gold). This argument arose because the gemarah made reference to a wooden Menorah overlaid with tin that was constructed in the times of the Chashmunaim and used in the Temple service.