Principle of inertia

The Principle of inertia is invoked to make sensation fit a picture of nature as pure exteriority: changes in an organ and the sensations associated with them must be caused by something other than themselves. The account then exposes a difficulty in that picture. To connect an external stimulus, a sense organ, and sensation, it postulates an inert inner environment—consciousness conceived as an object—which passively undergoes and even lives its sensations.

The Principle’s role in the causal account

The argument begins with the assertion that the sense organ is affected by a stimulus, while its protoplasmic and physicochemical modifications are not produced by the organ itself but come to it from outside. This claim is made to remain faithful to the Principle of inertia, which represents all nature as exteriority. Under that assumption, an effect cannot simply originate within the organ as spontaneous activity; its cause must lie elsewhere.

The same reasoning is extended from the stimulus and sensory organ to what the account calls the subjective system: the ensemble of internal properties attributed to the other-object. If a new modality appears in this subjectivity in connection with stimulation, it too must be produced by something other than itself. Otherwise, it would be severed from the stimulated organ, and the relation between them would become arbitrary.

Sensation as an inert object

To preserve a determinate connection, the account posits an objective unity for even the smallest and briefest perceptible stimulation and calls this unity sensation. It gives sensation inertia, making it pure exteriority and treating it, through the category of the “this,” as participating in the exteriority of the in-itself. Sensation’s cause and occasion are thus placed outside it: in a real object, the stimulus, and in a change affecting another real object, the sense organ.

This construction makes sensation exterior even to itself. Its reason for being does not reside in an internal fact of its own kind, but in external objects and their changes. The Principle therefore does more than explain why the organ is affected: it helps turn sensation into an inert, object-like term in a causal sequence.

The problem of the inner environment

The account nevertheless faces a problem of support. A being on one level of being, incapable of sustaining itself, cannot be determined to exist by an existent on a radically distinct plane. To provide sensation with being, the theory therefore introduces an environment homogeneous with sensation and likewise constituted in exteriority. This environment is called mind, or sometimes consciousness.

Consciousness is initially conceived as the consciousness of an Other—as an object—and then posited as also being one’s own consciousness in itself, so that the proposed relations between organ and sensation can be universal. The result is an internal space in which figures called sensations form on the occasion of external stimulation. Since this space is pure passivity, it is said to suffer its sensations.

Passivity and the theory’s tension

The account goes beyond describing consciousness as a matrix that accommodates sensations. It adopts a biological vision and claims that this internal space lives its sensation: life is made into a magical connection between a passive environment and a passive mode of that environment. The Principle of inertia thus supports a chain of external causes, but the theory must also posit an inner field to bridge the gap between physical stimulation and sensation.

That bridge preserves passivity rather than explaining sensation as something consciousness produces for itself. The passage’s critical force lies in showing how the commitment to exterior causation shapes the very subjectivity it is supposed to explain: sensation becomes an inert figure in an inner space, and consciousness is recast as an object that receives and lives it.