Reasoning and critical thinking concern the analysis and evaluation of arguments, where "argument" refers to the process of proving that one idea is true by appealing to another set of ideas as evidence. Reasoning and critical thinking are commonly understood as one aspect of the field of logic when considered broadly. In modern times, logic is often equated with formal logic, which doesn't concern itself with the truth or falsity of the evidence sited in an argument, focusing instead upon the logical connection between the evidence and the idea whose truth is allegedly established by the evidence. Such connections are called "inferences." Reasoning and critical thinking, however, assess both the evidence sited in an argument and the inferences in virtue of which the conclusion supposedly follows from that evidence. Further, formal logic frequently employs quasi-mathematical methods to assess the strength of an inference. In contrast, reasoning and critical thinking appeal to a wide variety of non-formal techniques when evaluating inferences. A large part of critical thinking also involves identifying fallacies of reasoning and then avoiding them in making one's arguments.