John Stuart Mill (1806 – 1873), a British philosopher and political economist, was an influential liberal thinker of the 19th century. He was an advocate of utilitarianism, the ethical theory that was systemised by his godfather, Jeremy Bentham, but adapted to German romanticism. It is usually suggested that Mill is an advocate of negative liberty. However, this has been contested by many academics, notably Dr. David Walker of Newcastle University in England.