The best definition of common sense and self evident truth that I have able to come up with is simply what 90% of the people in the room have a consensus about. For example in a roomful of Orthodox Jews it's self-evident that gay marriage is immoral, while at a literary dinner party in New York City where most of the attendees are left oriented writers it's self-evident that gay marriage is moral.
I don't think that there is any self evident truth for all of humanity apart from trivial basic necessities i.e. food, water, and shelter, etc, not even that.
Another example would be evolution. While people of my generation evolution is a self evident truth. However, for people of an older generation there's more skepticism.
Most people of my generation also defer to the scientist for most things, but among the philosophically oriented it's understood that science operates within its own historical framework and may be subject to paradigm shifts.
For many scientists it's self evident that philosophy is irrelevant, while philosophers often hold themselves as above science, i.e. philosophy is the first science. Hegel, Heidegger, etc, all thought this.
Do you hold any truths that are so evident to you that you would dismiss anyone's system of thoughts or opinions based on his or her contradiction of that self evident truth along? For example, many humanists hold it to be self evident that men and women are "equal", and when Lawrence Summer dared to explain the discrepancy in the hiring of female professors at Harvard by referring to the male occupancy of the right far spectrum of the normal distribution of intelligence he was forced to resign. It was said to be "beyond the pale of legitimate academic discourse".
My sacred cow as of right now is Henry James. I consider it self evident that he was one of the greatest writers of all time. I will automatically dismiss (in my mind) the aesthetic opinions of anyone who disagrees (with regards to everything).
My political views are too extreme for me to dismiss someone's opinions based on their disagreement with what I consider to be self-evidently true politically.
What are your self-evident truths? Something you so strongly believe in that you would vote that person out of power if he tried to act as if what was self-evident wasn't self-evident?
If I was a member of an English professor and my head of my department tried to remove Henry James off the curriculum, he will surely reap the whirlwinds, if I have the power to conjure one.
There are other sacred cows of course but Henry James is just the most prominent one, because his merits are still somewhat controversial. It's still acceptable to dismiss him publicly, while no one would dare to dismiss say, Milton.
Edit: tempted to change title to "We hold these falsehoods to be scorn-worthy offenses".....