Solipsism

Solipsism names both a metaphysical claim that nothing exists beyond the self and a more restrained method that declines to go beyond the evidence of experience. In the account of the problem of other minds, the restrained version is internally coherent, but the alternatives to it do not solve the underlying difficulty: idealism either leaves the Other as an object constituted within one subject’s experience or appeals to an unsupported realism, while spatial separation and a divine witness likewise fail to establish a genuine connection between consciousnesses.

The two forms of solipsism

The problem begins with the Other as the self who is not oneself: a subject for whom one is an object. From the standpoint of idealism, that relation is difficult to conceive. The Other is treated as real, yet cannot be directly given as a subject in one’s intuition; even when posited as a subject, the Other remains an object of thought. Idealism therefore faces a choice: abandon the concept of the Other as unnecessary to the constitution of experience, or affirm a real communication between consciousnesses that exceeds experience.

The first choice is solipsism. Taken literally as the assertion that nothing exists outside the self, it becomes an unjustified metaphysical hypothesis, because it claims more than the field of experience can establish. Understood instead as a deliberate refusal to leave that field or make use of the concept of other subjects, it is logically consistent. This methodological form does not prove that other minds do not exist; it refrains from making a claim about them. The text characterizes behaviorism, associated here with Watson, as solipsism in this working sense: it can recognize psychic beings as objects within experience while withholding commitment to systems of representation organized by subjects beyond it.

Why rejecting it does not settle the question

Kant and most post-Kantian thinkers affirm the existence of the Other, but the account argues that appeals to common sense or deeply rooted tendencies cannot justify that affirmation within idealism. To assert other minds as real while retaining idealism abruptly breaks its framework and falls back into metaphysical realism. The resulting position treats consciousnesses as separate systems that can communicate only from outside, implicitly restoring the notion of substance and leaving their reciprocal exteriority unexplained.

The reversal exposes a shared assumption beneath idealism and realism: both understand the distinction between the self and the Other as an external negation, a gap or nothingness given between two separate beings. Realism locates that separation in bodies, as though the difference between oneself and Paul were of the same kind as the difference between a table and a chair. Idealism replaces bodies with systems of representation, but still leaves each system enclosed within itself. In either account, space is made to separate consciousnesses, and an external relation would require a further witness to establish it.

The Other reduced to an image

If the relation is only indifferent exteriority, the Other cannot affect one’s being through the Other’s own being. The Other can then appear only as an object of knowledge, unified from a diversity of impressions by the knowing subject. The consequence is stark: the subject constitutes the Other within its experience, so the Other becomes an image, despite the theory of knowledge’s effort to reject the idea that other minds are merely images.

An external witness would be needed to compare that image with its model and determine whether it is true. Yet a witness standing outside both consciousnesses would also know them only through images. To provide direct knowledge of each, the witness would have to be internally connected to both—to be, in the account’s terms, both here with one consciousness and over there with the Other. Thus the problem is not simply a shortage of evidence; it arises from a conception of consciousnesses as externally separated in the first place.

God as an inadequate intermediary

The appeal to God, found in Leibniz, attempts to supply the required witness through creation. God would have to be both connected with each consciousness and distinct from each: able to apprehend each directly, yet impartial between them. Creation offers an image of that double relation, since the creator looks into what is created while the created thing closes upon itself as an objective being.

But this solution generates another dilemma. If creation is continuous, the self remains suspended between distinct existence and fusion with the Creator; if creation is a completed original act, the creator stands outside the completed creature and can know it only through images. God therefore reveals the need for an internal connection between consciousnesses without providing an adequate guarantee of the Other’s existence. Even God’s role as intermediary presupposes a connection between minds, since God is conceived as a Mind and as the quintessence of the Other.

The discussion consequently leaves neither literal solipsism nor an appeal to divine mediation as a satisfactory final account. Solipsism’s methodological restraint follows the limits of experience, while the rejection of that restraint, on the assumptions criticized here, risks dogmatic realism and the reduction of the Other to an object. The proposed direction beyond this impasse is an original internal negation: a relation in which the self and the Other are distinct yet each is determined through the other.