Charles Sanders Peirce (1839–1914) was an American philosopher who made many important ideas in the field of logic and the philosophy of science. He believed in the power of logic, which is the idea that if you use some type of reasoning, you can figure out the truth of a given situation. His ideas showed that clear communication and clear thinking are both essential for science to progress. He also believed that the universe works through cause and effect relationships and that our knowledge of the universe is always changing and developing.