Rabbi Akiva challenged Rabbi Eliezer's reasoning. You are deriving what is possible from what is impossible, he argued. Natural death is always beyond human control — it is impossible to prevent. But breaking and seizure can be either natural (unavoidable) or man-made (potentially avoidable). Deriving rules about avoidable events from an unavoidable benchmark creates a flawed comparison.
The objection struck home. Rabbi Eliezer reversed himself and adopted a different approach. Instead of deriving the breaking-and-seizure rules from the death category, he derived them from the stealing category. The Torah specifies that an unpaid guardian who allows an animal to be stolen is liable. The parameters of that liability — what constitutes reasonable care versus negligence — became the benchmark for breaking and seizure cases as well.
According to the revised framework: whatever standard of care makes a guardian liable for allowing theft, that same standard applies to breaking and seizure. If the guardian could have prevented the loss through reasonable effort but failed to do so, he is liable. If the loss truly was beyond his ability to prevent, he is exempt.
This exchange between Akiva and Eliezer demonstrates the self-correcting nature of Mekhilta discourse. A great sage proposed a derivation. A greater sage identified a logical flaw. The first sage accepted the correction and rebuilt his reasoning on a stronger foundation. The pursuit of legal truth took precedence over personal honor.