One of the things that the blogosphere has introduced me to the past few years is the pseudo-traditionalist Catholic. There are a lot of very good genuine traditionalist Catholics online, so nothing I say here should be taken as general indictment of that group, but there are also a lot of people online whose attempt to claim the traditionalist label is simply baffling. I suppose they go to Latin Mass in the Extraordinary Form, but this is a weak ground at best. They participate in the Gossip Fence -- an embarrassing amount of so-called traditional Catholicism online consists of gossip about other people, particularly complaints about problems they none of them are actually bothering to do anything about -- but ditto. In the big controversy about lying a while back, the most stubborn people I came across when it came to attacking people for insisting on the traditional Catholic view of lying all called themselves traditionalists. Traditionalist my foot. 'My opinions, whatever they happen to be' is never an expression synonymous with 'tradition'.
One of the things that I've noticed the Francis papacy bringing out around the big 'traditionalist' gossip fences online is a tendency to make wild accusations of Modernism. Modernism in the sense used here is a heresy; one should understand the label from the reason it is called a heresy and not reason on vague associations called up by the label. But there are certainly people who will call 'Modernist' anything that they don't like that sounds modern, just as there is a certain kind of liberal Catholic who will pin 'Americanist' (another heresy with a potentially confusing label) on anything they don't like that sounds vaguely American. So what I want to do here is to point out that, despite the fact that Modernism is indeed a popular heresy, and has been so for a century and a half at least, the conditions required for being a real Modernist (as opposed to having views that some over-imaginative and incautious person is quick to pin the label on) are fairly narrow. Modernism can show up in lots of different fields, in many different ways, but all of these different faces are faces of one basic idea, which we might summarize as 'true religion or faith is only inside, not outside'.
The major document on the subject is Pius X's 1907 encyclical, Pascendi dominici gregis. You will sometimes find people claiming that this encyclical is a mish-mash, and that its characterization of Modernism makes it practically anything, but this is not true. For one thing, the Modernists proper were a well-defined group who wrote books like Il programma dei Modernisti; and for another, the encyclical is actually quite unified in its characterization of the Modernists. What it is instead is a discussion of the way a single idea, placed in different fields of human thought, can do different kinds of damage. The essential Modernist error is to remove religion from the realm of reason, by taking reason and intellect not to apply to questions of God, the soul, and the like. And this is one of the reasons why its ramifications can be so protean: it is in reality, whatever the excuse for it, an attack on the competence of reason itself (whether in ourselves or in another), so it causes distortion in any rational field.
Thus the Modernist idea in the context of philosophy leads to the denial of the very possibility of natural theology, since it takes the subject of natural theology to be 'beyond' the capacities of the human mind. But it also eliminates the possibility of using rational arguments in favor of external authority and revelation, since such arguments can only be developed if reason can make at least probable inferences from external signs to religious conclusions. As Pius X puts it (sect. 6), "Modernists simply make away with them altogether; they include them in Intellectualism, which they call a ridiculous and long ago defunct system." But religion itself, of course, they can't deny; not only is it all around us, but Modernists are not antagonistic to religion at all; they think of themselves as reformers of religion, not deniers of it. In such cases they identify religion with a particular kind of internal consciousness. The identification is total. Since religion is moved out of the realm of intellect and reason, and its conclusions cannot then be grounded in rational discourse about objective facts or the pronouncements of an external authority, the only thing it could be grounded in is something like a subjective sentiment. Thus Modernism has the same structure as Fideism. All religious authority is the authority of some subjective attitude or feeling. This subjective state is then called faith, or conscience, or religious sentiment, or God-consciousness, or spirituality, or any number of other things, since the exact vocabulary doesn't matter for the purpose of identifying the family of thought. The terms themselves may be entirely reasonable and legitimate; what the Modernist is doing, however, is restricting them entirely to something that is purely subjective and internal. This makes everything in religion a matter of subjective sentiment. The 'Christ of faith' (subjective sentiment) is sharply divided from the 'Jesus of history' (objective fact); dogmas and religious doctrines are merely attempts to form imaginative pictures expressing this sentiment and in turn to express these pictures in symbolic words, so that they are really just handy tools for capturing and communicating the internal experience; doctrine admits not only of development but change without restriction, as people feel; faith and religion become purely individual matters rather than matters in which one is responsible to the whole community, because faith and religion are entirely in yourself and not rooted in rationally discerned fact or external authority; tradition is entirely just a history of how people have tried to communicate an original experience; sacraments are merely signs communicating spiritual sentiment that have their efficacy entirely in spiritual sentiment; the authority of the Church is just the more-or-less agreement of everyone's sentiments, and thus is a matter of everyone 'voting' with their 'consciences'; Catholics ought to keep their religion private and distinct from their citizenships; and so on and so forth.
Thus, as Pius X says, the basic Modernist idea tends to proceed on three interconnected fronts: agnostic (reason is removed from religious questions), immanentist (everything religious is only a matter of subjective consciousness), and evolutionist (religion can develop without any constraint or limitation because it is merely the expression of a subjective state of mind). Modernism is thus a denial of reason and external authority in matters of God, the soul, worship, and the like. Or, as I said above, it can be seen as the view that true religion is entirely internal rather than external; anything external is at best a symbol or metaphor for the internal, and only gets its authority from the internal.
Through all of this, note that it is the exclusive character of Modernism that causes the problem. The problem is not that it claims that the internal is important to faith, or even necessarily that it is the most important; the problem is that it removes everything else, whether it be rationally discerned objective truth or the guidance of external authority. The problem is not that they appeal to subjective experience; it is that they reduce everything religious to subjective experience. The problem is not that they treat doctrines as symbolic; it is that they treat doctrines as only symbolic, and only symbolic of subjective experiences, at that. The problem is not that they emphasize the importance of individual conscience; it is that they understand individual conscience in such a way that in matters of religion it admits of no correction by reality or authority. And so on and so forth.
So getting back to the pick-a-little-talk-a-little over the gossip fence in certain quarters. As I wander here and there I've increasingly heard the charge of Modernism being thrown around; Pope Francis gets charged with it, liberal-leaning cardinals get charged with it, and so forth. Now, it is entirely reasonable to criticize anyone if they propose something incoherent or to point out when something is problematic. But claiming that something is a heresy is something that you really had better be able to pull off if pressed for reasons. And Modernism, again, has certain direct implications about external authority. It is extremely unlikely that Pope Francis or any Cardinal holds the view that the authority of the hierarchy can be ignored when it fails to fit with the general subjective consensus. Indeed, it is obviously false of Francis and I would be astonished if there is any Cardinal arguing that our own religious consciousness trumps the authority of the Church. Bishops of any kind may be stupid; they may be irrational; they may be imprudent; they may be reckless; they may be clericalist heretics; but they tend not to insist that the bishops have no inherent authority. In order for someone to be a Modernist, they have to transfer all the weight of genuine authority in religion to individual religious consciousness, rejecting the view that religion is also rooted, in a foundational way, in reason and ecclesiastical authority.
So now, if someone claiming to be a traditionalist calls someone a Modernist who clearly is nowhere denying that reason and ecclesiastical authority are essential to the Catholic faith, feel free to bop them on the head for abusing the term.