Makkot 5: Conspiring Witnesses and Execution, Numbers, Consequences

A brief overview of today's daf:

Mishna: The punishment of money is divided among conspiring witnesses but lashes are not. The proof lies in two texts that each describe actions as wicked: 

Gemara: Witnesses are only understood as conspiring when they describe those liable to receive lashes and those liable to receive the death penalty.  Just like the death penalty cannot be divided, lashes cannot be divided.  Though each of the witnesses' actions caused the victim's money to be vulnerable, they can combine what is owed to equal the victim's potential loss.  

Mishna: Conspiring witnesses must be attempting to impeach the witnesses themselves and not just their testimony.  Only two witnesses are required to counter the testimony of many other witnesses to prove that all of the other witnesses were conspiring.

Gemara: Witnesses who claim one was murdered because they saw it happen - but the angle at which they were situated makes that almost impossible would be called false witnesses.  However, perhaps they had superior eyesight. Similarly, witnesses who claim that a person could not have been present at a crime committed at a certain time are called 'conspiring'.  Could the person have had a flying camel (a racing camel)?  The Gemara speaks of other cases where crimes are committed but the timing is difficult to judge - could it have been Shabbat, with more stringent rules applying, or on Sunday?

The rabbis consider those who hire witnesses.  In fact the rabbis wonder if the presumptive state is that of dishonesty and that Jewish witnesses should be assumed to be false witnesses.  Do they even know the content of the testimony?  

Mishna: Conspiring witnesses are only executed after the trial has ended and one has been pronounced guilty.  The Sadducees, who follow Torah law without rabbinical interpretation, would execute conspiring witnesses only after the victim was in fact executed, for they stand by "life for a life".  

Gemara: The rabbis delve into the halachot of forbidden sexual relationships to prove that one does not derive a prohibition based on an a fortiori inference.  They question whether or not one can be sentenced to be exiled based on these same considerations.  Simon ben Shatach and Rabbi Yehuda ben Tabbai both adhered to the notion that both witnesses must be judged as conspiring for either to be punished.  The rabbis then argued about whether or not these rabbis were correct in their thinking, and how we will ever be able to discern the truth of their words after their deaths.

Mishna: Why does Deuteronomy 17:6 mention that two or three witnesses can testify that one should be killed?  Isn't two enough?  The rabbis consider a number of possible factors, including the strength of three witnesses when only two are required, other numbers of witnesses, and what might void another's testimony, among others.