Science is the pursuit and application of knowledge and understanding of the natural and social world following a systematic methodology based on evidence. Science includes scientific methods such as objective observation, which refers to measurement and data (possibly, although not necessarily, using mathematics as a tool), evidence, experiment, critical analysis, and verification. The four major branches of science are: mathematics and logic, biological science, physical science, and social science. The key words that best define science are thus: objective observation + evidence-based approach + application of scientific methods = general truths The basic problem of such an explanation of science lies in the very definition of what general truths are, what kind of evidence is required to prove them, and how to arrive to this kind of evidence through objective observation. The simplest premise to answer these questions would be: through logic and critical thinking.