Writing at a time in which speculative ways of thinking appear to be undergoing a reprise across the social sciences and humanities – whether through engagements with speculative cosmology (Stengers, 2006), speculative empiricism (Debaise, 2017), speculative fabulation (Haraway, 2011), speculative research (Wilkie et al., 2017), or speculative realism (Bryant et al., 2011) – in this chapter we introduce Speculative Geographies and our motivation for assembling the collection as a way of considering what concepts and practices of speculation might mean for geography, and how speculation might itself be conceived as geographical. In approaching the relationship between speculation and geography, we introduce the book as a collective desire to complicate the modes of thought used to evaluate experience by crafting alternatives, pluralising perspectives, and thereby problematising the immediately given. Far from abstract thinking, in this chapter we conceptualise speculation, after A.N. Whitehead, as a task of thinking abstractions – a style of thinking that prioritises an openness to what thought might become, and which therefore reconfigures empirical problems beyond what seems given in an immediate experience. The chapter traces key genealogies of this speculative practice including speculative philosophy, speculative fiction, and speculative design. Finally, we provide an overview of how the three themes of the book – ethics, technologies, aesthetics – speak to the chapters making up this edited collection.