Question: The Mishna Achrona (Oholos 1:8) asks why in the Michilta it is taught on the verse “when you open a pit or dig a pit” if on the opening you are liable all the more so for digging it, so why need the verse, rather the verse must be teaching us that we don’t exact capital punishment or lashes from logic, it needs a verse. And Tosfos in the first chapter of Bava Kama says that it is obvious that opening is included in digging and still you need a verse. In Gemara Makkos it asks if testimony works with two witnesses then why does the Torah also mention 3? But what’s the question, we hold ein onshin min hadin, you can’t punish based on logic, and we would not enact a death penalty if 3 witnesses testified, for example someone killed someone else but because it is impossible to have 3 without two then obviously they should be able to make someone guilty of a capital crime, so why isn’t this any different then digging and opening a pit where each one needs a verse though once we know one then obviously we know the other?
A. Digging a pit entails opening something which was not there before whereas opening a pit entails opening a hole that was already opened before but currently is covered.
B. 3 witnesses are all separate who just happened to come together to testify about the same thing.
Answer: Since opening and digging really are two different actions then it makes more sense to say a kal vachomer so therefore a verse is needed to punish but two out of three witnesses are the same as two witnesses therefore it makes more sense to say they are the same thing as that is why the Gemara asked why a verse is needed.