Tarski's Threat to the T-Schema Cian Chartier Abstract: This thesis examines truth theories. First, four relevant programs in philosophy are considered. Second, four truth theories are compared according to a range of criteria. The truth theories are categorised according to Leitgebā€™s eight criteria for a truth theory. The four truth theories are then compared with each-other based on three new criteria. In this way their relative usefulness in pursuing some of the aims of the four programs is evaluated. This presents a springboard for future work on truth: proposing ideas for different truth theories that advance unambiguously different programs on the basis of the four truth theories proposed.