 Following the early Doctrine of Science, we must, according to Fichte, accept three fundamental principles (Grundsätze) of human knowledge without which we could not even make sense of the idea that we can know that there is something real at all. The first states that self-consciousness or the I is a spontaneous (unconditioned) act that in taking place creates or posits the I as having existence or being (ein Akt, der im Vollzug sein eigenes Sein schafft). The I understood as this self-positing act that gives rise to its own being and reality Fichte characterizes as “deed-act”, also translated as “Act” (Tathandlung), and it is through this deed-act/Act that what we take to be real or having being comes to the fore. Fichte arrives at what he presents as his first principle of human knowledge on the basis of two assumptions. The first is that we can only properly be said to know assertions (judgments or propositions) which exhibit the character of certainty [Gewissheit], or those which thus express what is actually and certainly the case; the second maintains that a regress in the process of justification with regard to such assertions can only be avoided if we are able to furnish some principle or fundamental proposition which is “utterly unconditioned” [schlechthin unbedingt] (as Fichte puts it), one, that is, which cannot be derived from any other principle, and which, for its part, is of such a kind that it alone guarantees the utter certainty, and thus the indubitability, that is, the immunity to skeptical objections, of a given proposition. This second assumption leads him to the claim that the unquestionable certainty of a proposition can never be demonstrated discursively (by appeal to purely conceptual considerations) or intuitively (by appeal to any sensuous perception), and that, on the contrary, the ground of unconditional certainty can only be found in the constitution of self-consciousness itself. Fichte identifies as an appropriate method by means of which the principle in question can be derived a procedure which he calls “abstractive reflection”. This kind of reflection, according to Fichte, takes its point of departure from a proposition which everyone regards as unquestionably certain, from a so-called “fact of empirical consciousness”. From this fact, this indubitable proposition, the process of reflection isolates (abstracts) the elements which belong to the content of such a proposition, i.e., belong to that about which the proposition asserts something. What is supposedly left, after this abstraction, is simply the form of the proposition which consists precisely in affirming the ascription, or non-ascription, of a predicate to a subject. The proposition which Fichte selects as the point of departure for his “abstractive reflection” is the logical law of identity in the form “A = A”, a law that is rightly regarded as utterly certain, i.e., certain without recourse to any further grounds and thus as intrinsically certain. This fact alone already shows that we have the capacity (the faculty) of claiming something as certain without reference to any further grounds, or, in Fichte’s own terminology, of “positing” something absolutely [etwas schlechthin zu setzen]. Reflection on this fact shows according to Fichte that the utter certainty of the law of identity is grounded in the positing activity of the I (which in this case posits identity), an activity which consists precisely in postulating the being of what has been posited as identical. Otherwise this activity would not be real, would have no being.