The leading philosopher born in 1906 known for their work in moral philosophy and political theory is John Rawls. His influential book, "A Theory of Justice," published in 1971, introduced the concept of justice as fairness, significantly shaping contemporary political philosophy. Rawls argued for principles that would govern a just society, emphasizing the importance of ensuring equality and liberty for all individuals. He proposed the idea of the "veil of ignorance" as a thought experiment for determining fair social principles, greatly affecting discussions on justice and ethics in philosophy and public policy.