John Gregory (June 3, 1724–1773) was a Scottish physician whose writings made an important contribution to the field of medical ethics. He wrote the first philosophical, secular, clinical medical ethics in the English language, appearing as Lectures on the Duties and Qualifications of a Physician(1772). The work built on Francis Bacon’s philosophy of medicine, and David Hume’s science of morals, and was particularly influenced by Hume's "principle of sympathy". His work on medical ethics achieved wide influence in Britain, Europe, and America, from the end of the 18th century well into the 19th century.  A portrait of John Gregory is held by the National Portrait Gallery, Edinburgh
"I may reckon among the moral duties incumbent on a physician, that candour, which makes him open to conviction, and ready to acknowledge and rectify his mistakes. An obstinate adherence to an unsuccessful method of treating a disease, must be owing to a high degree of self-conceit, and a belief of the infallibility of a system. This error is the more difficult to cure, as it generally proceeds from ignorance. True knowledge and clear discernment may lead one into the extreme of diffidence and humility; but are inconsistent with selfconceit. It sometimes happens too, that this obstinacy proceeds from a defect in the heart. Such physicians see that they are wrong; but are too proud to acknowledge their error, especially if it be pointed out to them by one of the profession. To this species of pride, a pride incompatible with true dignity and elevation of mind, have the lives of thousands been sacrificed."
The Gregory Family
John Gregory was born into a family rich in intellectual tradition. His father, James Gregory (1674- 1733), was Professor of Medicine at King's College, Aberdeen, and the son of James Gregory (1638-1675), the Elder, Professor of Mathematics first at St Andrews University and then at Edinburgh University; he is credited with the discovery of calculus, and was a contemporary of Sir Isaac Newton. The brother of James Gregory the Elder was the inventor David Gregory (1627-1720), whose son David Gregory (1661-1708) became Professor of Mathematics  James Gregory the Elder was the son of John Gregory (1598 - 1652), minister of Drumoak in Aberdeenshire, and his wife Janet Anderson; altogether, their descendants included fourteen professors of various subjects including medicine, chemistry, philosophy, mathematics and history. John Gregory himself became Professor of Medicine at Edinburgh University, as did his son James Gregory (1753-1821). 
- John Gregory’s Writings on Medical Ethics and Philosophy of Medicine Springer, ISBN 978-0-7923-5000-2 (Print) 978-0-585-32315-2 (Online)
- McCullough LlB (1999) Hume's Influence on John Gregory and the History of Medical Ethics. The Journal of Medicine and Philosophy 24:376-95
- Truman JT (1995) The compleat physician: John Gregory MD (1724-1773). J Med Biogr. 3:63-70. PMID 11640039
- NPG D13907 'John Gregory' by Cook, published by William Bent, after Sir George Chalmers; line engraving, 1787
- McCullough LlB (2006)John Gregory’s medical ethics and the reform of medical practice in eighteenth-century Edinburgh J R Coll Physicians Edinb 36:86–92
- From Gregory J. Lectures on the Duties and Qualifications of a Physician. London:W. Strahan and T. Cadell; 1772. In: McCullough LB (editor). John Gregory’s Writings on Medical Ethics and Philosophy of Medicine. Dordrecht: Kluwer; 1998; 161–245.
- Papers of Professor James Gregory (1638-1675), the Elder
- Papers of the Gregory family of Aberdeen, Edinburgh, St Andrews and Oxford GB 0231 Aberdeen University, Special Libraries and Archives