The Torah says a person who strikes his father or mother "shall be put to death" (Exodus 21:15), but it does not specify the method of execution. The Mekhilta identifies this silence as legally significant. The phrase "he shall be put to death" appears without any qualification, without specifying stoning, burning, or decapitation. So what form of death does it mean?
Rabbi Yehoshiyah establishes a sweeping principle. Wherever the Torah uses the unqualified phrase "he shall be put to death" without specifying a method, the default form of execution is strangulation. You might think the court should choose the most severe form of execution available, since the crime is serious enough to warrant death. But Rabbi Yehoshiyah says the opposite. You are not permitted to incline toward severity. You must incline toward leniency.
Strangulation is considered the least severe of the four methods of court-imposed execution in Jewish law (stoning, burning, decapitation, and strangulation). When the Torah does not specify which method to use, the court must apply the mildest option. This is not a matter of judicial discretion. It is a binding principle of Torah interpretation.
Rabbi Yonathan agrees with the practical conclusion but offers a different theoretical basis. The default is not strangulation because it is lenient. It is strangulation because that is simply what the Torah means whenever it says "death" without qualification. Every unqualified "death" in the Torah is strangulation by definition. The distinction between the two Sages is subtle but real. Rabbi Yehoshiyah derives the rule from a principle of leniency. Rabbi Yonathan derives it from the inherent meaning of the word. Both arrive at the same ruling: unqualified death means strangulation.