This dialogue is the first to appear in Macroeconomic Dynamics. Other dialogues on topics of importance to macroeconomics will appear occasionally in this journal. Unlike interviews appearing in the MD Interview series, conversations appearing in the MD Dialogue series will not be focused on the life and work of a participant but rather on a particular research topic. Another distinction between the two series is the general format and structure. Each interview in the MD Interview series will include only one interviewee, although there may be multiple interviewers who jointly conduct an interview with a single interviewee (e.g., the interview of David Cass by Stephen Spear and Randall Wright in the preceding issue). In contrast, each dialogue will include at least two direct dialogue participants, and may or not be conducted by a third party to the conversation.