Jason / immanent transcendence has THIS to say concerning realism and nominalism.
The broader point, as I see it and as Jason articulates in his post, is that a speculative realist metaphysics is especially difficult if one endorses an immanentism gone so wild that it is impossible for there to be transcendence of the particular terms which comprise the immanent plane. The result, epistemologically speaking, is nominalism. Metaphysically speaking, immanence ultimately refers to one form of transcendence or another. The question becomes: is there such a thing as "pure" immanence? And, more basically, immanent to what?
A view of transcendence acceptable within an intelligent immanentist viewpoint might be something like taking transcendence to involve the recognition of an "ultimate governance" of immanent terms, where that governance states "there shall be no ultimate governance among the particulars." It seems that the non-contingent (transcendental) principle that "all is contingent" applies to particulars as well as universals, true, but it is the one reality to which contingency itself applies as a "functional" ground or transcendental "hyperground" which is determinative of all other grounds - that is, as a transcendental reality whose basis admits contingency within itself and yet still holds non-contingently (we may say "groundless" ground). Transcendence, ontologically, simply references recognition of these conditions, the possibility of any x - there can be more, so let there be more. There is no universal principle "locking in" the continuous metaphysical addition of particulars to an immanent plane. Epistemologically speaking transcendence is simply the ascension of thought through into being by speculating such conditions of novelty (and temporality) for any and all particulars and creative addition to them.
Metaphysically, transcendence involves something altogether different than what is traditionally understood (the invocation of a supernatural realm of universals): instead of concrete ground and universal, here metaphysics involves relations, function, and composition with respect to particulars. Speculation necessarily extends beyond the reality of singular terms, and realism admits both the reality of terms, relations between those terms, and then the generic functions applying to both terms and relations. Nominalism on the other hand is confined to "the show of the present moment." For the nominalist, there is no transcendence of even the singular self-term "itself," and thus terms are immanently "flattened" in a correlationist circle which begs all to be referred *back* to the present self, what is present for *it* without regard for any in-coming future experience (and so there is no way to proceed beyond the self to the "great outdoors" for the correlationist, even in a temporal sense). There is no identity other than the immediate first term of experience, there is no other particular to affect the first particular, there is no reality of relation between the two. One just has the circle of correlation: what exists exists *for* the first term of experience.
Stated differently, nominalism admits no room for the metaphysical relations between things, the compositional connections in any given instant. (And yet stated another way: There is no room for the sort of compositional particular that "behaves" as a universal in its own transcendental function. This is the worst kind of correlationism, as the transcendental function is what permits there to be real non-contradiction, real identity, measure and principle without specifically human measurement or reason.)
Transcendence, given the above, is available from within and between the particulars; yet it is in some sense what renders particularity as such as a process. It is recognition of ground (as transcendence), but as "grounding activity" (transcendental condition) - from each particular and to each particular in a nexus of relation, function, and composition (relatively transcendent).
In the below lecture, using process philosophy and cosmology we find out why any speculative metaphysics must be grounded in the empirical and in the particular, and being so cannot be nominalistic. However we also learn that to deny what is most generic about nature, what is in effect transcendental, leads to an unfounded skepticism relegated to that "show of the present moment" without regard for an other. Using Whitehead, we find out that any metaphysical description of nature takes us "beyond" the particular and toward the generic, the universal, the transcendent, even if in the future temporal creation of a self.
An Introduction to Process Cosmology
by David Ray Griffin
This lecture provides an introduction to the relationship between process thought and cosmology, and the potential role or influence that the former should have in the latter.