Reading already uses three things without naming them: a direction the line takes, an interval it spans, the carrying that closes it. These three roles are succession, distinction, and exchange. The first two sections give how Reality constrains; this one gives what it is, in the sense of how it is built: not a thing lying beneath the constraining, but the structure the constraining runs on. These might be taken for three features Reality happens to have. If they were, removing them should leave a bare version of Reality behind. But stripping them does not leave a simpler Reality. It removes what makes *possibility-talk* intelligible at all.

Strip succession: no before and after, and therefore no sense in which anything could *occur* or *be done*. Strip distinction: no here rather than there, no this rather than that, and therefore no candidate state to be specified. Strip exchange: no bearing, no transfer, no linkage by which one state could give way to another.

To specify a way things could be at all is to specify a determinate configuration, this state rather than that. Without succession, distinction, and exchange there is no determinate configuration to describe, and nothing for modal vocabulary to pick out: no ‘one way rather than another’ to range over. What goes missing is not some particular way things are, swapped for a stranger one; it is the contrast any possibility-claim needs, this rather than that, with nothing left to carry it.

These three names carry forward into [§1.3](<1.3 Change.md>) and return in [§1.4](<1.4 Three Conditions.md>) as the three Conditions (Temporality, Spatiality, Physicality), borne in Reality by Time, Space, and Substance. The roles (succession, distinction, and exchange) name what change requires; the Conditions and their bearers name the structure in which that requiring is real.

The grounding here is not *ipsum esse subsistens* ("being-itself-subsisting") renamed. Classical theism's ground is simple: without parts, without internal articulation, the same across every aspect one might name. That commitment is the working-out of perfect-being theology and *actus purus* ("pure act"), not a freestanding axiom. The doctrine is contested from within the tradition itself: Aquinas holds it in its strongest form, while Plantinga rejects it outright and Swinburne sets it aside, reserving *simplicity* for a virtue of theory choice rather than the doctrine; Chapter 5 takes up the engagement at strength. Reality's grounding is articulated: succession, distinction, and exchange are not structures Reality happens to have but the constitutive structures Reality cannot fail to have. The inversion the book argues is not over the structures the tradition attributed to its ground (necessity, sufficiency, indifference to the contingent) but over what those structures belong to. They belong to Reality itself, not to a subject standing outside it.

Two readings are open here, and choosing between them is a priority question, closed at [§4.1.10](<4.1.10 The Source of Possibility.md>). On one, the three roles are necessary because Reality essentially is that way — part of what Reality is, in Fine's sense of *real definition* (an account of what a thing essentially is, not of what its word means). On the other, they are merely necessary as a structural feature of the modal field, without an essence-prior-to-modality. The constitutive language above ('cannot fail to have,' 'what it is') names the structural shape of the primitive modal field, not an essence prior to it from which the modal facts derive.

Any candidate for what lies beneath the roles (a creator, a necessary ground, a primordial state, a brute fact) must be offered as possible. The trouble is that the offering already occurs within succession, distinction, and exchange: the candidate has to be named, distinguished from what it grounds, and related to the possibility it is meant to explain. That is pressure, not refutation; the fuller defense belongs to Chapter 2.[^1-1-3-grounding-pressure] The comparison with naturalism that takes the cosmos as a brute fact, without any further necessity posit, is engaged at strength in Chapter 4. Chapter 2 identifies whether the demand that any candidate be offered as possible functions as a Principle of Sufficient Reason premise, a weaker explanatory norm, or a modal-status constraint; the engine driving the argument is named there, not here.

And the roles do not come and go. For the roles to lapse (for Reality to step outside the direction, the difference, the link, even briefly) is for there to be no direction within which the lapse could occur, no interval across which it could be measured, no linkage by which anything on the far side could connect to anything on this side. The alternative to Reality running is not a different Reality. It is the absence of the conditions any alternative would need.

[^1-1-3-grounding-pressure]: A line of objection holds that the relevant kind of grounding is precisely not a succession (not even in logical space) but atemporal: a relation of metaphysical dependence that runs from ground to grounded without requiring temporal priority. Even granted at full strength, the objection does not relieve the local burden: any candidate for what makes possibility possible must be nameable, and naming requires the roles it was supposed to provide. Succession, distinction, and exchange do not arrive one by one; they arrive together, and when they arrive, possibility is the name for their being in place together. The atemporal-grounding position is engaged at strength in [§5.1.1](<5.1.1 Rasmussen's Foundation Argument.md>).


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← [1.1.2 Reality Permits](<1.1.2 Reality Permits.md>) | [1.2 Modal Status](<1.2 Modal Status.md>) →
