Abstract: While agreeing with Seana Shiffrin that any free speech theory must depend on assumptions about our need for free thinking, I am sceptical about her claim that her thinker-based approach provides the best explanation for freedom of speech. Her argument has some similarities with Mill’s argument from truth and with self-development theories, though it improves on the latter. But the thinker-based approach does not show why political discourse, broadly construed, is protected more strongly in all jurisdictions than gossip and sexually explicit speech. Nor does it explain why the ‘mass’ speech of corporations and the mailings of political parties and charities are fully protected by provisions such as the First Amendment. My article concludes with some reflections on the relationship of abstract political theory such as Shiffrin’s to constitutional law; abstract theory must inevitably make some compromises if it is fully to explain constitutional jurisprudence.