Gabriel Rodrigues

This chapter aims to present and explore the section “Identity” from the “Doctrine of Essence” in Georg Wilhelm Friedrich Hegel's Science of Logic. Based on discussions within the Hegel and Speculative Idealism Group - Hegel Laboratory (GHIE-LH), after an introduction, the chapter begins by providing the context of the section within the development of the Science of Logic and then analyzes the conceptual determinations of identity, paragraph by paragraph, following Hegel's exposition. In the section studied, Hegel seeks to overcome several presupposed and assumed dichotomies between identity and difference. For him, identity is co-determined by difference, and difference is also co-determined by identity, in a greater unity. In particular, neither of these is justified as a self-subsistent moment, since they only have meaning in relation to the whole of which they are a part, which imposes the need for them to be considered in relation to their other.

First, the chapter expounds on the logical-ontological status of identity in the Doctrine of Essence of the Science of Logic, showing that, for Hegel, identity is not an empty formal principle (A = A), but the proper way in which essence relates to itself through negativity. Identity, as reflection in itself, implies difference; as determined difference, it implies diversity and opposition; and as self-subsistent opposition, it culminates in contradiction, which dissolves into the form of the ground. It is argued that this path, if properly understood, prevents, or at least hinders, the view of identity as mere external equality. From this, making a connection with Hegel's philosophy of religion, it is shown that the proper content of consummate religion is precisely the God who posits himself as other, objectifying himself, and who, in this otherness, remains absolutely identical to himself—that is, God as spirit. By articulating logical identity as a unity of self and other, the chapter explains why central religious determinations (such as the Trinity and reconciliation) are not representational additions to logic, but the speculative realization of the same concept of concrete identity, that is, the identity that is preserved in differing and realized as a return to itself.

This chapter aims first to present Hegel’s concept of identity in the “Doctrine of Essence” of the Science of Logic, and then to explore how Hegelian logic can contribute to understanding the problem of substitutivity. The analysis contextualizes identity within the history of philosophy and logic, outlining its formal characterization and limitations, and situates the substitutivity problem in debates initiated by Leibniz and further developed by Frege, who distinguished sense and reference to explain substitution failures in intensionally loaded contexts. The methodological approach is interpretative and analytical, based on a careful reading of Hegel’s text and conceptual analysis, using an example — the Masked Man Fallacy — to highlight the limitations of formal identity and unrestricted substitutivity. It is argued that Hegel’s distinction between abstract identity (formal and tautological) and concrete identity (reflexive and mediated by difference) allows for a reinterpretation of substitutivity failures as structurally necessary rather than exceptional. The chapter concludes that Hegelian logic provides a conceptual framework to understand identity as a dynamic process and to engage with contemporary issues in logic and philosophy of language.

The scarcity of transitional forms in the geological record was a problem concerning 19th-century transmutation species theories. According to Charles Robert Darwin (1809-1882), it was perhaps the most serious objection to his proposed theory in the several Editions of The Origin of Species, departing 1859. Although Darwin and other scholars proposed explanations, this problem persisted until the 20th century in the Modern Synthesis. In the 1970s, two American palaeontologists, Niles Eldredge and Stephen Jay Gould (1941-2002), presented the punctuated equilibrium hypothesis as an alternative to the gradualism that Darwin and the Modern Synthesis admitted. This paper aims to discuss the proposal of the punctuated equilibrium. In addition, the foundation Gould and Eldredge gave and how the scientific community reacted to it. The analysis showed that punctuated equilibrium complemented Darwin's proposal and the Modern Synthesis. Thus, criticisms such as opposition to these ideas are unjustified. The authors sought to base their hypothesis on evidence from their and other authors' investigations. The reactions to the proposal varied during the period studied (1972-1993). Still, it got more accepted among palaeontologists and met with more significant restrictions among those who dedicated themselves to genetics, mainly to population genetics.