Fichte proceeds from the general principle that the I ("das Ich") must posit itself as an individual in order to posit ("setzen") itself at all, and that in order to posit itself as an individual, it must recognize itself to a calling or summons ("Aufforderung") by other free individual(s) — called to limit its own freedom out of respect for the freedom of the others. The same condition applies to the others in development. Mutual recognition ("gegenseitig anerkennen") of rational individuals is a condition necessary for the individual I. The argument for intersubjectivity is central to the conception of selfhood developed in the "Foundations of the Science of Knowledge" ("Grundlage der gesamten Wissenschaftslehre", 1794/1795).