Chapter 1 introduces the main questions to be tackled in the book, tracing a crime case from the discovery of a body to the verdict of a court. How do we generate initial hypotheses from sparse information? How do we develop our hypotheses as we gather new evidence? How do we make sense of a large body of conflicting evidence to reach a final decision? The crime case highlights the challenges we face: to explain what actually happened – the web of cause and effects that led to the death – but also to evaluate the evidence, assessing the many reports, claims and counterclaims. I argue that our minds are better prepared for explaining than evaluating.

Hypothetical thinking involves imagining possibilities and mentally exploring their consequences. This chapter overviews a contemporary, integrative account of such thinking in the form of Jonathan Evans’s hypothetical thinking theory. This default-interventionist, dual–process theory operates according to three principles: relevance, singularity, and satisficing. To illustrate the explanatory strength of the theory a range of empirical evidence is considered that has arisen from extensive research on hypothesis testing, which involves individuals generating and evaluating hypotheses as they attempt to derive a more general understanding of information. The chapter shows how key findings from hypothesis-testing research undertaken in both laboratory and real-world studies (e.g. in domains such as scientific reasoning) are readily explained by the principles embedded in hypothetical thinking theory. The chapter additionally points to important new directions for future research on hypothetical thinking, including the need for: (1) further studies of real-world hypothesis testing in collaborative contexts, including ones outside of the domain of scientific reasoning; (2) increased neuroscientific analysis of the brain systems underpinning hypothetical thinking so as to inform theoretical developments; and (3) systematic individual-differences investigations to explore the likely association between people’s capacity to think creatively and their ability to engage in effective hypothetical thinking.

Exploratory research is an attempt to discover something new and interesting by working through a research topic and is the soul of good research. Exploratory studies, a type of exploratory research, tend to fall into two categories: those that make a tentative first analysis of a new topic and those that propose new ideas or generate new hypotheses on an old topic. This chapter examines the history of exploratory studies, offers a typology of exploratory studies, and proposes a new type of exploratory study that is especially helpful for theorizing empirical material at an early stage. It argues that exploratory studies are an important part of a social scientist’s toolkit.