In Western strains of Christianity there is the Trinitarian doctrine of the dual procession of the Spirit from the Father and the Son. Eastern Christianity rejects this notion. They happen to believe that the procession only occurs from the Father. The West rejects this. The agreement over the East and the West is that the Father begets the Son and the Spirit proceeds from the Father. The East rejects that the Spirit proceeds from the Son and the West confirms the negation of this proposition. The point of this post is to demonstrate that under certain philosophical presuppositions the procession of the Spirit from the Father and the Son is more reasonable than not.
The Western view is more reasonable because it has a lot more theological and philosophical explanatory scope. Since the Spirit proceeds from the Father and the Son is begotten by the Father how do we distinguish them? Well one might say that they have different contingent relational properties such as the Spirit is the one who sanctifies the church or the Son is the one who purchases our redemption…etc. The problem is that these relational properties are contingent and as a result they just happen to be the case but they don’t have to be the case. They don’t tell us anything essential to the Son or the Spirit they are only accidental relation properties. So for example in a possible world W* where there is no creation what do we really know about the differentiation between the persons of the Trinity, specifically the Son and the Spirit? Nothing! And that seems like a very strange and odd thing to say about the persons of the Trinity in whom we are suppose to know and have a relationship with. The East recognizes that there is a difference between procession and being begotten, but how can they explain this? They are both coming from the Father in terms their personhood is being sustained from all eternity past, so where is the difference between these persons? They could say that it is just mysterious and the causation *has* to be different but we just don’t know how to reasonably distinguish them. This view seems completely ineffable.
The West on the other hand doesn’t seem to be in hot water on this score. For we can say that the difference between being begotten and proceeded from is that being begotten from is from one necessary causal relation whereas being proceeded from is two necessary causal relations (since of course the Spirit presumably comes from the Father and the Son). So if one wants to have more explanatory scope in their Trinitarian theology and philosophy then they ought to adopt the western view of the Trinity.