Anchoring structure in experience

The conditions page ends with a debt. The shape any total theory is forced into says the world’s basic ingredients carry an inside and an outside at once, which means the structure of experience and the structure of the physical world have to be one structure. Positions in this family have historically asserted that identity and moved on. This page is the argument for it.

Why anything needs anchoring

Start somewhere that has nothing to do with consciousness.

A physical theory describes the world by specifying structure — what relates to what, in what pattern. Structure alone underdetermines its subject. Given a description couched purely in abstract structural terms, any collection of things of the right cardinality can be arranged to satisfy it. This is the Newman problem, and it has been on the table for a century: a theory that ascribes only structure to the world says far less than it appears to. Something has to tie the structure down.

Philosophy’s standard ways of supplying that tie each pay a known price — primitive causal powers, primitive naturalness, a bare posit that some relations are the intended ones. Each is a thing you have to add.

Experience is the one candidate that requires nothing added. It is the single piece of the world each of us occupies rather than describes. Whatever else is uncertain, that there is something it is like to be reading this is not an inference from a model. Taken as one structure with the physical, experience becomes the anchor the world’s description needs — offered as the best explanation on the table, with each posit priced openly rather than smuggled.

Where the geometry enters

An anchor that stays at the level of “experience, somehow” does no work. The advance is in making it specific, and geometry is what makes it specific.

An embodied perspective acts within a space of orientations: the ways a body, or a viewpoint, can be turned. That space has a definite mathematical form. It is real projective 3-space, RP³ — and its fundamental group is two-valued, π₁(RP³) = ℤ₂.

That two-valuedness is not an abstraction. Hold an object in your palm and rotate it through a full turn: your arm is twisted. Carry it through a second full turn in the same direction and the twist comes out. That is the belt trick. It demonstrates the topology rather than proving anything: the same two-valuedness is what a neutron interferometer registers as a phase reversal in matter under a 2π rotation. One is a thing you can do with your hand, the other an instrument reading, and they are tracking the same structure.

What this establishes, and what it does not: the space of orientations is RP³, as mathematics. That the whole space experience is laid out in has the same structure — not just its orientations — is the further step, and this framework marks it as a posit rather than a result. It is stated again below, and it is the claim to argue with.

Where this structure came from

Credit where it is owed. The projective structure came into this framework from perceptual phenomenology, not the other way round. Modelling the field of consciousness, Rudrauf and colleagues (2017) give experienced space projective form, derived from properties of perception — depth, perspective, the relation between viewpoint and viewed — with initial psychophysical support, awaiting replication. Reading that work is what pointed at RP³ here.

So this is a source rather than a corroboration, and the difference matters. Two lines of inquiry arriving at the same structure independently would be evidence for it. One line with an origin is not, and presenting it as convergence would be claiming support the situation does not supply.

The framework does not owe them the geometry itself. The space of orientations of a rigid body is RP³ as a matter of mathematics, and the two-valuedness of its fundamental group is a theorem — those hold whatever anyone’s model of perception says, and they are what the argument above actually rests on. Their model also keeps experienced space distinct from the physical world, so identifying the two is this framework’s claim to defend, not something inherited along with the structure.

The claim, stated plainly

This is the framework’s most consequential commitment, so it is worth stating outright rather than letting it accumulate out of the argument.

Projective Process Monism holds that experiential structure and physical structure are one structure, read from inside and from outside. That is flatter than the usual formulation, which casts experience as the intrinsic nature of an independently described physical world. The identification is argued where it is sharpest, at the geometry of orientation. Carrying it across to the whole space experience is laid out in — not just orientation — is a further step, and it is marked as a posit rather than proved.

Withhold the identification entirely and the two structures still match, step for step. What you give up is the claim that they are one structure rather than two that happen to agree.

What is not being claimed

The target the conditions page describes is real and unoccupied, and the geometry of orientation is a serious place to start on it — because it is the one place the structure of experience and the structure of the physical world can be checked against each other without either being assumed.

That is an argument, and it is the argument this site makes. It is not a completed construction. The combination debt — how small bearers of experience come to constitute a single subject — remains open, with a working draft and no result.

Where this goes

RP³ is three-dimensional, and the complex projective space that has it as its real locus is fixed by that. Which space, and what the projection between them looks like, is the Arena.

The paper behind this page is One Structure, Inside and Out, on the papers page.