A philosophical theory is an idea or concepts that attempts to explain different phenomena in the world. There are several synonyms for this term, including philosophic thought, philosophical speculation, abstraction, and philosophical concept. Other synonyms include philosophical system, philosophical doctrine, and philosophical thesis. These terms all signify a system of beliefs and principles that attempt to explain the world and the human condition. They are all interconnected concepts that are used in philosophical discourse, and, although they share similar meanings, they each carry a unique connotation. Whether used in a discussion of metaphysics, ethics, epistemology, or other branches of philosophy, these synonyms for philosophical theory all denote a critical and rigorous approach to the exploration of ideas.