In response to a USA Today editorial praising Jon Huntsman for his decision to not sign pledges as a candidate, Rick Santorum writes a piece defending the importance of signing pledges:

To me, in a time when our nation’s problems are so vast and so deep, a candidate should be able to meet that serious responsibility with something more than just promises. We are asking the voters to invest their special privilege and right in us. We are asking our fellow citizens for the most precious commitment they can give in a democracy: their vote.
In turn, it shouldn’t be too much to ask that we offer a guarantee as well. With all candidates say and do, we should not shrink from offering our civic commitments, either. Thanks to groups concerned with issues ranging from the national debt to the value of innocent life, we candidates have now been given an opportunity to offer something as serious as the vote we are asking for — a solid commitment, a solemn promise. When we sign these pledges, that is what we are doing, solemnizing our words.
Every candidate has heard the cynicism about politicians: “Oh, they will say one thing now, but just wait until they are elected.” A lot of that is true about too many politicians and elected leaders. Pledges are our way of saying: “Not us.”