William Petty (1623-1687) was an English economist, philosopher, and scientist known for his contributions to political economy and statistics. He is often regarded as one of the founders of modern economics. Petty developed the concept of "political arithmetic," which involved the use of quantitative data to analyze economic and social issues. His work laid the groundwork for later economic theories. In addition to his economic theories, Petty was also a notable figure in the field of medicine and cartography. He served as a physician during the English Civil War and was involved in mapping Ireland, contributing to the understanding of its geography. His interdisciplinary approach influenced various fields, including demography and public policy.