This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Fichte's Wissenschaftslehre, the name he gave to his evolving system of philosophy across roughly two decades, from its first lectures in 1794 to his death in 1814, begins from a principle stated so tersely it can look almost too simple to carry the weight later placed on it, that the I posits itself. Behind the brevity lies an argument about what has to be true for consciousness to exist at all. Following Kant, Fichte held that the I think must be capable of accompanying every representation a mind has, but he pushed past Kant by asking what kind of activity that accompanying self consciousness actually is. His answer is that it is not a fact discovered about an already existing self but an act that produces the self it is an act of, which is why Fichte coins a special term for it, calling it a Tathandlung, a fact act, a deed that is simultaneously an action and its own product. The self, on this view, does not first exist and then happen to posit itself. Positing itself is what it is to be a self at all.
That starting point creates an immediate problem, since a self that merely posited itself and nothing else would have no way of distinguishing itself from anything, and self consciousness without contrast is arguably not consciousness at all. Fichte's system therefore has to explain how the I comes up against something not itself, and the concept he introduces for this is the Anstoss, usually translated as a check or an obstacle. The Anstoss is the I's original encounter with its own finitude, the point at which the self discovers that it is limited by something it did not simply produce by an act of will. Fichte is careful not to let this collapse back into a Kantian thing in itself sitting mutely behind appearances. The I does not passively receive the check from outside so much as respond to it, building up the structure of ordinary experience through a graduated series of mental acts that Fichte traces from raw feeling through sensation, then intuition, then finally concept.
A persistent misreading of Fichte, one the secondary literature has had to correct repeatedly, takes the Wissenschaftslehre to be a theory of some grand cosmic or absolute I, a single infinite consciousness of which finite individuals are mere fragments. The texts themselves point the other way. The system's actual conclusion is that the only I that can exist or act at all is a finite, embodied, individual one, a particular person situated among obstacles and other people, not an abstraction floating free of any body or circumstance.
That last qualification, other people, turns out to matter more than the early expository sections of the system suggest on a first pass. Working out the theory of natural right, Fichte found he needed a further move beyond the Anstoss, arguing that the I can only posit itself as an individual, and so only become a self at all, by recognizing itself as summoned or solicited by another free individual outside it. Selfhood, in other words, is not achieved alone in confrontation with a mute obstacle but requires another rational being who calls on the self and is in turn recognized. This doctrine of mutual summons anticipates the master argument for which Hegel would later become famous, and the historical debt runs in the open, since Hegel's own account of right developed in close and pointed engagement with what Fichte had already worked out.