Mark Spahn sent a link to this blog post by Jonah Goldberg. Goldberg's mistake is assimilating addiction ("enslavement" to a drug) to state coercion. Classical liberalism limits state power over the individual; it does not seek to eliminate self-enslavement. Put differently, classical liberals are opposed to paternalism. People have a right to be stupid. Put differently still, the liberty that classical liberals seek to maximize is liberty from the state; it is not liberty from addiction.