Some of the arguments made in this book, such as the proposition that bicameralism makes a change to the status quo more difficult than unicameralism, may seem intuitive, even trivial, to the reader. Other arguments, like the rarity of a bicameral core in more than two dimensions, or empirical evidence, such as the connection between chamber composition and length of intercameral negotiations, dispute the conventional wisdom in the literature or point legislative research in a new direction.

In this chapter we review the different theories and arguments presented in the literature with a critical eye, explaining which are sound and justified, which require restrictions or modifications, and which are false and unsupported by the evidence. Finally, we raise other methodological, theoretical, and empirical issues that merit a more sustained investigation.

The chapter is organized in three sections, ordered from the more specific and the less objectionable to the more general and controversial. The first section deals with topics and ideas that are considered intuitive or at least well known. We show how we generalize these ideas or how we restrict their domain of application. The second section demonstrates that on a series of issues, we disagree both in theory and in evidence with the existing literature. The third part discusses the research agenda generated by this book. Given that some items fall into multiple categories, there is an overlap of subject matter among the three parts.