Ian MacDougall Hacking CC FRSC FBA (February 18, 1936 – May 10, 2023) was a Canadian philosopher specializing in the philosophy of science.

[5] Hacking was married three times: his first two marriages, to Laura Anne Leach and fellow philosopher Nancy Cartwright, ended in divorce.

[2][6] Influenced by debates involving Thomas Kuhn, Imre Lakatos, Paul Feyerabend and others, Hacking is known for bringing a historical approach to the philosophy of science.

He is sometimes described as a member of the "Stanford School" in philosophy of science, a group that also includes John Dupré, Nancy Cartwright and Peter Galison.

Foucault's approach to knowledge systems and power is also reflected in Hacking's work on the historical mutability of psychiatric disorders and institutional roles for statistical reasoning in the 19th century, his focus in The Taming of Chance (1990) and other writings.

Fugue, also known as "mad travel," is a diagnosable type of insanity in which European men would walk in a trance for hundreds of miles without knowledge of their identities.

On August 25, 2009, Hacking was named winner of the Holberg International Memorial Prize, a Norwegian award for scholarly work in the arts and humanities, social sciences, law and theology.

Hacking also gave the Howison lectures at the University of California, Berkeley, on the topic of mathematics and its sources in human behavior ('Proof, Truth, Hands and Mind') in 2010.