2.1 The Social Model
Throughout the gospels, the first two persons of the Trinity are referred to as ‘Father’ and ‘Son’. This suggests the analogy of a family, or, more generally, a society. Thus, the persons of the Trinity might be thought of as one in precisely the way that, say, Abraham, Sarah, and Isaac are one: just as these three human beings are one family, so too the persons of the Trinity are one God. But, since there is no contradiction in thinking of a family as three and one, this analogy removes the contradiction in saying that God is three and one. Those who attempt to understand the Trinity primarily in terms of this analogy are typically called Social Trinitarians. This approach has been (controversially) associated with Greek or Eastern Trinitarianism, a tradition of reflection that traces its roots to the three great Fathers of the Eastern Church—Basil of Caesarea, his brother Gregory of Nazianzus, and their friend Gregory of Nyssa. More recently, Richard Swinburne has defended a version of this view according to which each of the three divine persons has all of the essential characteristics of divinity: omniscience, omnipotence, omnipresence, moral perfection, and so forth. However, these three persons are unlike other persons with which we are familiar (and, importantly, unlike the gods of familiar polytheistic systems as well) in that they have necessarily harmonious wills, such that their volitions never come into conflict, and that there is a perfectly loving relation that also necessarily obtains among them. Further, this view is compatible with traditional claims of dependence relations among members of the Trinity. Traditional formulations of the doctrine hold that the Father generates the Son and that Father and Son jointly give rise to (or spirate, literally “breathe forth”) the Holy Spirit. Such relations are possible as long as one person causes the other in such a way that the causing relation has always obtained, and it is impossible for the relation not to obtain.
On this sort of view, there is one God because the community of divine persons is so closely inter-connected that, though they are three distinct persons, they nonetheless function as if they were a single entity. If we were to consider a set of three human persons, for example, who exhibited these characteristics of necessary unity, volitional harmony, and love, it would hard to regard them as entirely distinct in the way we do ordinary persons. And that is, of course, just what the doctrine aims to put forth.
Perhaps this view seems to lean too strongly in the tritheistic direction. How could the social Trinitarian respond to this worry? One way would be to focus attention on exactly what is required in order for many “things” to jointly compose another single “thing.” My (one) body is composed of (many) atoms. My (one) car is composed of (many) parts. Thus, likewise, the one God might be thought of as composed of three Persons. And, indeed, this is exactly what many Social Trinitarians have wanted to say. Thus, for example, C. S. Lewis has famously suggested that God is composed of three persons in just the way that a cube is composed of six sides. More recently, J. P. Moreland and William Lane Craig (2003) argued that the relation between the persons of the Trinity can be thought of as analogous to the relation between the three “dogs” that compose Cerberus, the mythical guardian of the underworld.
Still, part-whole analogies raise additional worries of their own. Is God a fourth thing in addition to the divine persons? If so, what sort of thing is God? Apparently we face a dilemma: Either God is a person, or God is not. If the former, then we have a quaternity rather than a trinity. If the latter, then we seem to commit ourselves to claims that are decidedly anti-theistic: God doesn't know anything (since only persons can be knowers); God doesn't love anybody (since only persons can love); God is amoral (since only persons are part of the moral community); and so on. Bad news either way, then. Thus, many are motivated to seek other models.
2.2 The Psychological Model
Many theologians have looked to features of the human mind or “psyche” to find models to help illuminate the doctrine of the Trinity. Historically, the use of psychological analogies is especially associated with Latin or Western Trinitarianism, a tradition that traces its roots to Augustine, the great Father of the Latin-speaking West. Augustine himself suggested several important analogies. But since each depends for its plausibility on aspects of medieval theology no longer taken for granted (such as the doctrine of divine simplicity), we'll pass over them here and focus instead on two analogies in this tradition that have been developed by contemporary philosophers.
Thomas V. Morris has suggested that we can find an analogy for the Trinity in the psychological condition known as multiple personality disorder: just as a single human being can have multiple personalities, so too a single God can exist in three persons (though, of course, in the case of God this is a cognitive virtue, not a defect)(Morris 1986). Others—Trenton Merricks for example—have suggested that we can conceive of the persons on analogy with the separate spheres of consciousness that result from commissurotomy(Merricks 2006). Commissurotomy is a procedure, sometimes used to treat epilepsy, that involves cutting the bundle of nerves (the corpus callosum) by which the two hemispheres of the brain communicate. Those who have undergone this procedure typically function normally in daily life; but, under certain kinds of experimental conditions, they display psychological characteristics that suggests there are two distinct spheres of consciousness associated with the two hemispheres of their brain. Thus, according to this analogy, just as a single human can, in that way, have two distinct spheres of consciousness, so too a single divine being can exist in three persons, each of which is a distinct sphere of consciousness.
It might appear that the analogy with multiple personality disorder is no better off than the “butcher, baker, candlestick maker” analogy, and therefore similarly leads us into modalism. After all, the personalities of those who suffer from the disorder might seem to be nothing more than distinct manifestations of a single (albeit divided) consciousness which, like the roles of Fred, cannot be manifested at the same time. And the commissurotomy analogy might appear on closer inspection not to be interestingly different from the social analogy. For if there really can be several distinct centers of consciousness associated with a single being, then the natural thing to say is that the “single being” in question is either an additional sphere of consciousness composed of the others, or else a “society” whose members are the distinct spheres of consciousness. But it is far from clear that these criticisms are decisive. And, at least on the surface, these two analogies seem to have a great deal of heuristic value; for both seem to present real-life cases in which a single rational being is nonetheless “divided” into multiple personalities or spheres of consciousness.
2.3 The Constitution Model
The third and final solution to the problem of the Trinity that we want to explore invokes the notion of ‘relative sameness.’ This is the idea that things can be the same relative to one kind of thing, but distinct relative to another. More formally:
RELATIVE SAMENESS: It is possible that there are x, y, F, and G such that x is an F, y is an F, x is a G, y is a G, x is the same F as y, but x is not the same G as y.
If this claim is true, then it is open to us to say that the Father, Son, and Holy Spirit are the same God but distinct persons. Notice, however, that this is all we need to make sense of the Trinity. If the Father, Son, and Holy Spirit are the same God (and there are no other Gods), then there will be exactly one God; but if they are also distinct persons (and there are only three of them), then there will be three persons.
The main challenge for this solution is to show that the relative-sameness assumption is coherent. This challenge has been undertaken by a number of prominent contemporary philosophers, including Peter Geach and Peter van Inwagen. Despite the efforts of these philosophers, however, the relative-sameness assumption has remained rather unpopular. The reason appears to be that its defenders have not provided any clear account of what it would mean for things to be the same relative to one kind, but distinct relative to another. Recently, however, Michael Rea and Jeffrey Brower have suggested that reflection on statues and the lumps of matter that constitute them can help us to see how two things can be the same material object but otherwise different entities. If this is right, then, by analogy, such reflection can also help us to see how Father, Son, and Holy Spirit can be the same God but three different persons.
Consider Rodin's famous bronze statue, The Thinker. It is a single material object; but it can be truly described both as a statue (which is one kind of thing), and as a lump of bronze (which is another kind of thing). A little reflection, moreover, reveals that the statue is distinct from the lump of bronze. For example, if the statue were melted down, we would no longer have both a lump and a statue: the lump would remain (albeit in a different shape) but Rodin's Thinker would no longer exist. This shows that the lump is something distinct from the statue, since one thing can exist apart from another only if they're distinct. (Notice that the statue can't exist apart from itself.)
It might seem strange to think that a statue is distinct from the lump that constitutes it. Wouldn't that imply that there are two material objects in the same place at the same time? Surely we don't want to say that! But then what exactly are we to say about this case? Notice that this isn't just a matter of one thing appearing in two different ways, or being labeled as both a statue and a lump. Superman and Clark Kent can appear differently (Clark Kent wears glasses, for example); but the names ‘Superman’ and ‘Clark Kent’ are really just different labels for the same man. But our statue analogy isn't like this. Superman can't exist apart from Clark Kent. Where the one goes, the other goes too (at least in disguise). But the lump of bronze in our example apparently can exist apart from The Thinker. When melted, the lump survives while The Thinker does not. If that's right, then, unlike Superman and Clark Kent, the statue and lump of bronze really are distinct things.
Philosophers have suggested various ways of making sense of this phenomenon. One way of doing so is to say that the statue and the lump are the same material object even though they are distinct relative to some other kind. (In ordinary English, we don't have a suitable name for the kind of thing relative to which the statue and the lump are distinct; but Aristotle and Aquinas would have said that the statue and the lump are distinct form-matter compounds.) Now, it is hard to accept the idea that two distinct things can be the same material object without some detailed explanation of what it would mean for this to occur. But suppose we add that all it means for one thing and another to be “the same material object” is just for them to share all of their matter in common. Such a claim seems plausible; and if it is right, then our problem is solved. The lump of bronze in our example is clearly distinct from The Thinker, since it can exist without The Thinker; but it also clearly shares all the same matter in common with The Thinker, and hence on this view is the same material object.
By analogy, then, suppose we say that all it means for one person and another to be the same God is for them to do something analogous to sharing in common all of whatever is analogous to matter in the case of divine. On this view, the Father, Son, and Holy Spirit are the same God but different persons in just the way a statue and its constitutive lump are the same material object but different form-matter compounds. Of course, God is not material; so this can only be an analogy. But still, it helps to provide an illuminating account of inter-Trinitarian relations, which is all that we are currently asking for.
This account is not entirely free of difficulties however. Most importantly, it does not directly answer the question of how many material objects are present for any given region, lump, or chunk. Is there an objective way of deciding how many objects are constituted by the lump of bronze that composes The Thinker? Are there only two things (statue and lump) or are there many more (paperweight, battering ram, etc.)? And if there are more, what determines how many there are? Unless we can answer this question it is hard to know why the “divine matter” constitutes exactly three persons (and not more).
