If liberty of thought is suppressed ...this would undemine the trust which is the first essential of a state; detestable flattery and deceit would flourish, giving rise to intrigues and every sort of honest behaviour.
Gist of Idea
Without liberty of thought there is no trust in the state, and corruption follows
Baruch de Spinoza (Tractatus Theologico-Politicus , 20.11)
Spinoza specifically defends philosophy, as the epitome of freedom of thought.
Spinoza,Benedict de: 'Theological-Political Treatise', ed/tr. Israel,Jonathan [CUP 2007], p.255