The concept of speculative thinking is in many ways ambiguous. First, the concept of 'speculation' refers, on the one hand, to philosophical research, i.e., to the need for philosophy to remain committed to 'pure' thought and not to bend to instances allogenous to conceptual ones, while, on the other hand, it refers to financial transactions, aimed at profiting from fluctuations in market prices. Second, even within philosophical discourse, the term remains equivocal. At times, 'speculation' refers to an inquiry that - precisely by being merely speculative - seems detached from the practical concerns of the world, thereby indicating the essential theoretical element of philosophical inquiry; at others, the term marks the extreme experience of thinking in which ordinary discursiveness touches its limits. After a period of relative oblivion, the notion of the 'speculative' has returned today within contemporary philosophical debate. This special issue focuses on the notion of 'speculative thinking', both in its Hegelian and neo-Hegelian interpretations and in contexts that partially diverge from that tradition, aiming to philosophically explore the term's rich and varied meanings.