H. E. Baber has a fairly well-known paper, Eucharist: Metaphysical Miracle or Institutional Fact?, in which she proposes an account of real presence in the Eucharist. The background for it can be found in Michael Dummett's speculations on transubstantiation, which are flawed in a number of ways (to take just one example, he fails to grasp that Aquinas does not hold that the Body of Christ is indistinguishable from bread, because the former has a much wider range of effects than bread could possibly have; they are indistinguishable in sensible appearance, but the senses on their own never tell us what things are, but only what they apparently are); but Baber goes an interesting direction, arguing that the real presence is an 'institutional fact'. As she notes, this is a version of 'transignification'. If we have a bit of metal, what makes it money? We collectively take it to be so, and what this means is that we have a set of 'deontic powers' that we collectively recognize as belonging to it. And, of course, it is true, not fiction, that it is money; anyone who denied that a penny was money on the ground that it was visibly just a bit of metal would be wrong. Similarly, if I point to some mountains and say, "There's Canada," it would be a sign of stupidity to respond that it was obviously just some mountains. This is usually said, following Searle, to be caused by 'declaration', although I think it's often a misleading word, since to cover all of the things that it would have to, it would have to cover some radically different kinds of actions. But Baber's view, using the term, is that the Church declares individuals to have the authority to declare bread and wine the Body and the Blood, and such a declaration is consecration.
This makes plenty of sense as an Episcopalian account; it is, of course, radically inadequate for a Catholic account, since it does not give a very convincing account of the Fourth Lateran, "we receive from God what he received from us" (it only connects to the Incarnation by representation), nor the Tridentine "our Lord Jesus Christ, true God and man, is truly, really, and substantially contained under the species of those sensible things" (it only gives the 'truly' -- Baber doesn't make a distinction between true presence and real presence, but what she describes would only be the former from the Catholic perspective), and makes no sense of the Catholic notion that Christ is both Priest and Sacrifice -- that is, it has to be Christ, not the Church, that is the principal agent. And, of course, it's a deliberate attempt to give a purely non-transubstantial account, which would make it a general nonstarter for Catholics from the get-go.
But this is, again, because it's broadly Episcopalian and such accounts of sacraments inevitably involve a weak notion of sacrament. But the account actually works fairly well for certain sacramentals.
Sacramentalia, or sacramentals, are very diverse. They can be called 'minor sacraments' (and indeed I often think that this is less misleading when one is considering the history of sacramental theology), for the same reason that they are called 'sacramentals' -- because, as the CCC says, they "bear a resemblance to the sacraments" (CCC 1667). They only bear a resemblance, however; they are sacred signs, but instead of operating by direct action of Christ the High Priest, they work as part of the intercessory prayer of the Church. Blessings, consecrations, and exorcisms are the most basic kinds, but by extension we include the objects that prayed with -- as the catechetical saying goes, Protestants pray with words, Catholics pray with words and things. Holy water is holy water because it is part of the prayer of the Church; the whole Church is praying with it. A 'deontic powers' approach, sometimes also called a 'deeming approach', works quite well here.
In talking about the effects of sacraments and sacramentals, Aquinas at one point makes a distinction between three ways in which things can be involved in the remission of venial sin:
(1) by infusion of grace
(2) by disposing the soul to repentance
(3) by being a movement of reverence to God
The major sacraments are examples of (1). The examples Aquinas gives for (2) are general confesson (i.e., not the sacrament), beating one's breast in the Confiteor, and saying the Lord's prayer. Examples he gives for (3) are "a bishop's blessing, the sprinkling of holy water, any sacramental anointing, a prayer said in a dedicated church". I would suggest that we can see cases of (1) as being cases in which God acts as principal agent; they are cases of divine deeming, but 'deeming' on its own is not an adequate account of what God does in them, because they are active instruments of divine grace. Cases of (3) involve deeming by the Church in its general prayer to God. Water then becomes part of the prayer of the Church in much the same way sound does, by being deemed a sign as part of a prayer, and has its effects by way of being part of that prayer, just as sound does. And cases of (2) are cases in which the agent of deeming is the individual. Indeed, thinking in this way shows exactly how the sacramentals work: the holy water is part of the prayer of the Church and by crossing oneself with it you are deeming the holy water part of your prayer in particular, as well. This fits, first, with the way the Church talks about these things; secpnd, it fits standard theological accounts, like that of Aquinas; and third, it makes sense of the actual practice of sacramentals, and in particular, the way in which their use is not merely individual but both individual and communal, in a way that makes sense of what the Church says about their importance for devotion.
One complication is that while it makes perfect sense to talk about consecrations and blessings as deemings, it's not the bare deeming that is actually emphasized, but the particular kind of agency by which it is done. The Catholic view of sacramentals is not a view (like that which Baber seems to be assuming) that we, as a community, all have, for whatever reason, the convention that rosaries under certain conditions are blessed. The collective agency relevant to the Catholic minor sacraments is for the Catholic intimately and necessarily tied to the major sacraments, and blessings and the like depend not merely on convention but on sacramental character, by which we are assimilated to Christ through baptism, confirmation, or ordination. They are priestly deemings or designations by one who is sacramentally united to the person of Christ and to the whole Church already, and deems or designates by virtue of that fact. "Sacramentals derive from the baptismal priesthood" and "the more a blessing concerns ecclesial and sacramental life, the more is its administration reserved to the ordained ministry" (CCC 1669).
