Conscience, majority views, and the natural law

Eduardo notes that, in fact, most people in the United States do not believe in the "equal dignity and worth of every human being from conception to natural death" and do not believe that a "blastocyst" is a "full human being."  I am sure that he is right.  That said, it still seems to me that Michael S. is right to suggest that federally funded embyro-destroying research is, in fact, "inconsistent with America's deeper and core commitment to the equal dignity and worth of every human being from conception to natural death."  After all, that most Americans do not see the inconsistency does not eliminate it, does it?  I take it Michael was not suggesting that those Americans who support federally funded embryo-destroying research are hypocrites, but only that, because an embryo is, in fact, a human being, most Americans' support -- however well meaning -- for such research is not consistent with their commitment to the equal dignity and worth of every human being.

With respect to the natural law, Steve S. observes that most Americans do not accept the Church's teaching that it is immoral to destroy human embryos for research purposes, and states that "if natural law is written on our hearts, the Catholic position should be capable of defense without resort to authority."  I'm not a natural-law theorist, but I agree with Steve that we should be able to establish the immorality of destroying human embryos for research purposes without resort to authority.  But it is not clear to me why the fact that Americans do not believe that it is immoral to destroy embryos for research purposes establishes that the immorality of destroying embryos for research purposes can only be established by "resort to authority."

Steve continues, "[t]he law written on the hearts of Vatican Catholics does not appear to be the same as the law written on the hearts of millions of other Catholics and non-Catholics in American society and elsewhere.  Ironically the Vatican takes a countercultural position at the same time it asserts that the truth is written on our hearts."  Putting aside reservations I might have about the term "Vatican Catholics" -- and, again, admitting that I am not an expert in these matters -- I am not sure that natural-law theorists' claim is that the natural law is that which surveys establish is written on the hearts of most people.  Maybe Patrick Brennan or someone else can help me out here?