What is free speech? How is it under threat? And why should it be defended at all costs? In this succinct and insightful book, author Jamie Whyte contends that free speech brings fundamental benefits to society - it promotes the growth of knowledge and provides an essential bulwark against tyranny. He argues against new attempts to constrain free speech - particularly in social media - and critiques the rationale of politicians and activists who seek to limit it. And he proposes a key test - a limiting principle - which legislators and judges should apply against any proposed curtailment of free speech. Being offensive, for example, wouldn't pass this test - because important new ideas are often offensive to people whose worldview they challenge. Whyte also issues a rallying cry: Those who prize free speech must once again come to its defence - as he outlines exactly Why Free Speech Matters.