סותר את כותלו - sugyah summary!

The Gemara's objection to the "wall destruction" scenario is that such a person should have checked (who was in the public domain) prior to breaking the wall down.  Not doing so is grossly negligent, קרוב למזיד, and therefore dissimilar to the woodchopper case.  We proposed that the distinction here lies in the probability of people frequenting the forest vs. the public domain; although the woodchopper goes to an עיר מקלט, the likelihood of  hitting someone is low, but still present.  A Woodchopper's failure to take the precautions therefore remains on the level of שוגג and therefore חייב גלות.  The same lack of care of  a person demolishing a wall next to the רשות הרבים will likely produce an injury/death.  This level of liability cannot be atoned for in an עיר מקלט.

The Gemara then proposes an additional אוקימתא: that this all happened at night; by establishing this new fact, the Gemara hoped to bring it "closer" to the שוגג case of the Torah.  This was rejected by the Gemara's insistence that one at night, one would still have the same standard of care!  We gave two possible explanations as to what the Gemara could have been thinking in its הוא אמינא (assumption) and its מסקנא (conclusion):

a) In the הוא אמינא, the Gemara felt that the fewer people who frequent the רשות הרבים at night takes away the status of רשות הרבים and thereby equates it to the forest case of the Chumash.  The מסקנא holds that in the average public domain, nighttime does not reduce the amount of the passersby enough to justify the change of halachic status of the domain; it therefore remains קרוב למזיד
b) In the הוא אמינא, the Gemara felt that the fewer people who frequent the רשות הרבים at night takes away the status of רשות הרבים and thereby equates it to the forest case of the Chumash.
The מסקנא holds that once a public domain, always a public domain.  In other words - and as Carlos suggested in a move that won him the title of honorary Litvak - the sidewalk/street holds on to the "din" of רשות הרבים, and that halachic status simply does not fluctuate depending on the time of day.

This left us with the original problem in the mishna - what is הזורק את האבן לרה"ר גולה mean?  The Gemara re-couches the רשות הרבים as an אשפה - or a dump.  This is questioned: What's the scenario - היכי דמי? If many people pass through this dump, then the person is a פושע - grossly negligent - and the person would not go to an עיר מקלט; if people don't pass through, then the person is an אנוס, and therefore, blameless for the death!

Rav Pappa explains that it is a dump that people use as a bathroom at night, and not in the day.  The event happened during the daytime: Since it is not the typical time people come to use the bathroom, the case is not קרוב למזיד/פושע; since, however, they sometimes come to use it during the day - it is שוגג and not אנוס.  Therefore, the mishna's case is similar to the case of the Torah, ie the forest....