Paul Pillar points to the role of political tribalism to account for why certain groups of views tend to be associated with one another in American politics:

To the extent that the views of most voters on different issues do tend to be grouped into recognizable clumps, this is not because they are all going through the same coherent thought process—or any coherent thought process. It is because they are taking cues from groups with which they identify [bold mine-DL]. The groups might be organized interest groups or identifiable segments of society or the economy. They might be friends and neighbors—and if so, this would accentuate the regional patterns that Pinker addressed. Most of all, the cues come from political parties [bold mine-DL]. Most voters identify with Republicans or with Democrats, and because of this they tend to adopt most of the views that go with their preferred party. A person’s views on some issues might underlie the party identification in the first place, but once identified, the rest of the views in the clump associated with the selected party are usually taken on as well [bold mine-DL].

It’s easy to see how this works in practice, since national party coalitions in the U.S. are to some extent accidental and opportunistic alliances organized around common goals or, more often, shared opposition to the interests of other groups. The alliance comes first, and then come the arguments that seek to mobilize the various allies to work together on the grounds that they want at least some of the same things. For example, there is no logical connection between being a pro-life Christian and being reliably supportive of an activist U.S. foreign policy. There are many contradictions between these two, which a doctrine of “preventive” warfare only makes more glaring. Because supporting activist foreign policy has usually been presented as support for “strong defense” or a “strong military,” and because it is something that members of the Republican coalition are expected to support, pro-life voters have ended up supporting candidates that have been more inclined to favor large-scale “preventive” wars.

There is usually some attempt to create the appearance of coherence or at least common ground between different parts of the coalition. The old and “new” fusionisms are some of the products, which try to minimize or ignore the sometimes sharp contradictions between the assumptions and interests of different factions within a coalition. In the case of the “new” fusionism that some religious conservatives promoted for a time in the 2000s, the supposed common link between pro-life activism and activist foreign policy was their shared “moralism.” Rather absurdly, a “moralistic” foreign policy that led to an unnecessary invasion and caused over a hundred thousand deaths was supposed to have something in common with respect for the sanctity of life. Notably, Joseph Bottum, who imagined this “new fusionism,” made a point of rejecting the thesis that the social conservative-neoconservative alliance was simply accidental:

In the new fusionism, social conservatives and neoconservatives are not in any immediate contradiction. The wish to restore American patriotism, the struggle against abortion, annoyance at the dated elitism of an overweening judiciary, and the war in Iraq–these all seem to have become curiously interdependent issues.

Bottum’s original essay is useful for showing just how disconnected these “curiously interdependent issues” were and still are, which reinforces the impression that this alliance was always an accidental one. Bottum cited the increased tendency of contemporary neoconservatives to espouse pro-life views as proof of the “new fusionism,” but mostly what he was showing was the tendency of members in a political coalition to follow the prevailing party line. Bottum’s essay wasn’t an attempt to explain the contemporary Republican coalition so much as it was an effort to justify a continued alliance between pro-lifers and warmongers. The argument for the “new fusionism” was never very persuasive, but the forces of political tribalism have kept the alliance going long after it should have fallen apart.