How are we to understand the tradition that the patriarchs kept all of the mitzvot in the Torah (see for example the last mishna in Kidushin, Rashi Bereshit 32:5, etc.) in light of the many obvious logical contradictions that this would seem to imply?
For examples of such logical contradictions presented in a humorous/irreverent manner see: http://www.youtube.com/watch?v=N8MG9YtaZXg
Here are examples of apparent contradictions, some of which are brought up in the above video, and some of which are easier to resolve than others:
- The Chumash records instances of the avot seemingly violating certain mitzvot, e.g. Yaakov marrying sisters, Avraham serving milk/meat together
- The Chumash records instances of the avot being given mitzvot, e.g. Avraham and circumcision. So he clearly was not observing the mitzva of circumcision before this time. So when did he start observing various other mitzvot?
- Even with knowledge of future events, some mitzvot cannot logically be done at the time of the Avot, e.g. remembering things that have not yet occurred, such as the exodus and Amalek.
- Did they observe the mitzva of writing a Sefer Torah? Does that mean they knew of all events that are recorded in the Torah, including their own lives?
- How were the mitzvot of Teruma and Ma'aser observed, if there were no Kohanim & Levi'im yet? Did they being korbanot?