[benchaney]

The reason I say that eruv uphold the spirit of the law is because it is permissible to carry within walled cities. If it wasn't the intention of the law to make carrying outdoors completely off limits, then it is hard to see why an eruv violates the spirit of the law.

As for why it is necessary to have the physical construction: Just as the law doesn't intend to forbid carrying everywhere, it doesn't intend to permit it everywhere. The actual existence of a physical boundary prevents the perceived permissibility of carrying from expanding constantly. Without it, there would need to be some other equally arbitrary seeming rule about what constitutes a single community.

I also think it is important to mention that both the spirit and the letter of the law are quite important. Even setting aside the question of the spirit of the law, they are still necessary because they are mandated in a legalistic sense.

[bscphil]

Thanks for explaining, I think I see the idea more clearly now.