Next Sunday, Barack Obama will give the commencement address and accept an honorary degree from Notre Dame, the premier Catholic institution of higher learning in the United States. The situation has generated some controversy, given that President Obama's positions on abortion and embryonic stem cell research are at odds with official church doctrine. Where do most Americans, and particularly Catholics, stand on these issues and on the invitation?

Americans' views on abortion are complicated. It is not possible to find a pro-life or pro-choice majority in this country. Most people plant themselves firmly in the middle, seeing more gray than those in the pro-life or pro-choice camps. Their views have not shifted in any significant way since the Roe v. Wade decision in 1973 that legalized abortion.

The Gallup Organization and the National Opinion Research Center (NORC) have asked questions about abortion since the early 1970s, although they approach the subject differently. The responses have barely moved.

Gallup asks whether abortions should be "legal under any circumstances," "legal only under some circumstances," "illegal in all circumstances." In 1975, 21% said legal under all circumstances, 54% said only under certain circumstances and 22% said illegal in all. Gallup has asked the question 45 times since then, and the results have been remarkably stable. In 2008, those responses were 28%, 54% and 17%, respectively.

NORC asks respondents about their views on abortion by presenting different scenarios. In answer to one of NORC's questions, 40% in 1972 said it should be possible for a pregnant woman to obtain a legal abortion "if she is married and does not want any more children"; 36 years later, in 2008, 44% gave this response. Majorities disagreed in both years. In another NORC question, however, 79% of respondents in 1972, and 76% in 2008, said it should be possible for a pregnant woman to obtain a legal abortion "if she became pregnant as a result of rape." In short, people generally oppose abortion when the circumstances of the pregnancy are under the woman's control, but accept it when the circumstances (rape or serious danger to a mother's health) are not.

In other surveys, around two-thirds of those surveyed consistently say abortion should be legal in the first trimester; a quarter give that response about second-trimester abortions, and only around 10% say it should be allowed in the third trimester. Again, these responses are stable across polls. People want abortion to be legal, but they are willing to put significant restrictions on its use. Perhaps surprisingly, men and women do not differ significantly in their views on abortion.

In new polls from the Pew Research Center, Catholics looked very much like the population as a whole in terms of its views on abortion. The real divisions were in the Catholic community itself--just 30% of white non-Hispanic Catholics who attend Mass weekly said abortion should be legal in all or most cases, while 61% of those who attend Mass less often said it should.

On stem cells, 49% of Catholics said it was more important to conduct embryonic stem cell research that might result in new medical cures, while 38% said it was more important not to destroy the potential life of human embryos involved in the research. Once again, non-Hispanic white Catholics who attended Mass weekly responded differently than those who attended less often, with 36% of the former group and 54% of the latter saying the research was more important.

As for Obama's invitation, 19% of Catholics responding to one poll had heard a lot about it, 33% had heard a little and 48% had heard nothing. Fifty percent of them said it was right for Notre Dame to invite Obama, while 28% said it was wrong and another 22% didn't know or refused to answer. But as in all of these cases, degree of religiosity mattered. Only 37% of regular Mass-goers said the invitation was right, while a higher figure--56%--who attend Mass less often said it was. It seems, at least based on these polls, that the Catholic community doesn't speak with one voice.

Karlyn Bowman is a senior fellow at AEI.