What I thought was rather nice about Alito's dissent is that he was able to properly identify actually what is at issue. That is, he identifies that the debate is merely over competing views of what marriage is, a purely philosophical question. I thought I'd copy/paste from the opinion:
By asking the Court to strike down DOMA as not satisfying some form of heightened scrutiny, Windsor and the United States are really seeking to have the Court resolve a debate between two competing views of marriage.
The first and older view, which I will call the “traditional” or “conjugal” view, sees marriage as an intrinsically opposite-sex institution. BLAG notes that virtually every culture, including many not influenced by the Abrahamic religions, has limited marriage to people of the opposite sex. Brief for Respondent BLAG (merits) 2 (citing Hernandez v. Robles, 7 N.Y. 3d 338, 361, 855 N.E. 2d 1, 8 (2006) (“Until a few decades ago, it was an accepted truth for almost everyone who ever lived, in any society in which marriage existed, that there could be marriages only between participants of different sex”)). And BLAG attempts to explain this phenomenon by arguing that the institution of marriage was created for the purpose of channeling heterosexual intercourse into a structure that supports child rearing. Brief for Respondent BLAG 44–46, 49. Others explain the basis for the institution in more philosophical terms. They argue that marriage is essentially the solemnizing of a comprehensive, exclusive, permanent union that is intrinsically ordered to producing new life, even if it does not always do so. See, e.g., Girgis, Anderson, & George, What is Marriage? Man and Woman: A Defense, at 23–28. While modern cultural changes have weakened the link between marriage and procreation in the popular mind, there is no doubt that, throughout human history and across many cultures, marriage has been viewed as an exclusively opposite-sex institution and as one inextricably linked to procreation and biological kinship.The other, newer view is what I will call the “consent-based” vision of marriage, a vision that primarily defines marriage as the solemnization of mutual commitment—marked by strong emotional attachment and sexual attraction—between two persons. At least as it applies to heterosexual couples, this view of marriage now plays a very prominent role in the popular understanding of the institution. Indeed, our popular culture is infused with this understanding of marriage. Proponents of same-sex marriage argue that because gender differentiation is not relevant to this vision, the exclusion of same-sex couples from the institution of marriage is rank discrimination.
The Constitution does not codify either of these views of marriage (although I suspect it would have been hard at the time of the adoption of the Constitution or the Fifth Amendment to find Americans who did not take the traditional view for granted). The silence of the Constitution on this question should be enough to end the matter as far as the judiciary is concerned. Yet, Windsor and the United States implicitly ask us to endorse the consent-based view of marriage and to reject the traditional view, thereby arrogating to ourselves the power to decide a question that philosophers, historians, social scientists, and theologians are better qualified to explore. Because our constitutional order assigns the resolution of questions of this nature to the people, I would not presume to enshrine either vision of marriage in our constitutional jurisprudence.
It's not the most incredible philosophy out there, but it's definitely succinct and on point. That it can be so obviously laid out and not addressed at the same time speaks volumes about our legal process in a lot of ways.