…why not say that there is a single substance, God, but that the existence of this substance grounds other, non-fundamental entities [i.e. the Father, the Son, and the Holy Spirit] that perhaps can be considered parts of God. …the existence of the whole is prior to the existence of the parts. For someone drawn to a social trinitarian sort of view that takes the members of the Trinity as parts of the Godhead, this might be an attractive picture to take since it unifies the members into a single substance in a way that won’t work so well if one takes the existence of the parts as prior to that of the whole.
See the conversation here at Ian’s blog, Philosophical Orthodoxy.
Note to certain smart-alec readers: no, “Philosophical Orthodoxy” isn’t a contradiction in terms. đź™‚