[Avodah] Cumulative P'sik Reishei (was Kosher Switch)

[Simon Wanderer]

Further to the discussions on the above topic, I would point to OC 136 re
walking/running over grass on Shabbos as a key sugya in this respect. From
memory, there is also an important footnote in the SSK on the difference
between this and the combing hair case.

My thoughts are that P'sik Reshei means inevitable, or near enough. I think
the chilukim between the cases must revolve around different types of
probabilities. 

-- SW