In the moral dilemma known to contemporary philosophers as the “trolley problem,” an out-of-control streetcar is on its way to killing five people. It can’t be stopped, and the potential victims can’t be pushed out of harm’s way; but by simply pulling a lever, the driver can divert the trolley to a different track. The catch is that a single person standing on the second track will be killed in the process. In the early 1950s, the great talmudist Avraham Yeshaya Karelitz (known as the Ḥazon Ish) considered a nearly identical problem; like the vast majority of both philosophers and ordinary people, he ruled that it is better to allow one person to be killed than five. But unlike the philosophers, who tried to approach the problem through various theoretical principles (e.g., “the greatest good for the greatest number”), he reached this conclusion through analogy to similar cases given in the Talmud. Moshe Koppel explains what the trolley problem implies about the role of intuition in halakhic decision-making:
Karelitz takes as his starting point those principles already established as normative, including the ruling of the Mishnah prohibiting handing over a hostage and other principles suggested by later commentators. He suggests an intuitive difference between the hostage case and [his version of the trolley problem]; this intuition is almost universal, as recent wide-scale studies suggest. Karelitz then translates this intuition into a rule that hinges on whether the resulting deaths are a direct consequence of the contemplated act or mere collateral damage of a defensive maneuver. He does not suggest that this is the only relevant criterion—and indeed philosophers raise numerous other possible criteria that Karelitz might very well accept as relevant.
Now, if we would . . . collectively reach the same conclusion based on our intuition, what advantage is there in deferring to rabbinic analysis of the sort that Karelitz and his colleagues offer? . . . Well, we pay a heavy price for formalizing halachic intuition, but we gain a great deal as well.
First of all, one can easily construct intermediate cases—say, diverting the train saves five people but kills four bystanders or kills a relative—where most people don’t have any clear intuition. A theory of trolley decision can serve us well in such cases. More broadly, then, articulated principles of halakhah serve us when we don’t have clear intuitions on the matter at hand.
Also, rules are easier to preserve than intuitions. Thus, under traumatic conditions—persecution, exile, dispersion, the sort of things in which Jews specialize—when our collective memory is likely to fail us, clear rules are more likely to remain stable than vague intuitions, especially if the rules are committed to writing. This is the meaning of [several] talmudic stories regarding the reconstruction of halakhah during periods of upheaval.