摘要：The starting point of this article is the ontological question: What makes it true that 2+2=4?, that is, what are the truth makers of mathematical propositions? Of course, the satisfactory theory in the philosophy of mathematics has to answer semantical question: What are mathematical propositions about? Also, epistemological question: How do we know them?, as well. Author compares five theories in the philosophy of mathematics, that is, five accounts of the nature of truth makers in mathematical discourse: fictionalism (there are no truth makers because entities of mathematics are fictions, though useful fictions); nominalism (mathematical propositions are true by definition, so the truth makers are in the language); physicalism (mathematical propositions are inductive generalizations from experience, so, the truth makers are physical facts in the world); conceptualism (mathematics reflects the way we think about things, so, the truth makers are ultimately psychological facts) and Platonism (mathematics is about per se existing mathematical reality).
