This timely book examines the role of fact-checking journalism within political policy debates, and its potential contribution to public engagement. Understanding facts not to operate in a political vacuum, the book argues for a wide remit for fact-checking journalism beyond empirically-checkable facts, to include the causal relationships and predictions that form part of wider political arguments and are central to electoral pledges. Whilst these statements cannot be proven or disproven, fact-checking can, and sometimes does, ask pertinent critical questions about the premises of those claims and arguments. The analysis centres on the three dedicated national British fact-checkers during the UK's 2017 snap general election, including their activity and engagement on Twitter. The book also makes a close political discourse and argumentation analysis of three key issue debates in flagship reporting from Channel 4 News and the BBC.