Conceptual engineering is thought to face an ‘implementation challenge’: the challenge of securing uptake of engineered concepts. But is the fact that implementation is challenging really a defect to be overcome? What kind of picture of political life would be implied by making engineering easy to implement? We contend that the ambition to obviate the implementation challenge goes against the very idea of liberal democratic politics. On the picture we draw, the implementation challenge can be overcome by institutionalizing control over conceptual uptake, and there are contexts – such as professions that depend on coordinated conceptual innovation – in which there are good reasons to institutionalize control in this fashion. But the liberal fear of this power to control conceptual uptake ending up in the wrong hands, combined with the democratic demand for freedom of thought as a precondition of genuine consent, yields a liberal democratic rationale for keeping implementation challenging.