 But secular idealists and logical positivists concede that there are some actual unknown truths. How can they continue to believe that all truths are knowable? Astonishingly, these eminent philosophers seem refuted by the pinch of epistemic logic we have just seen. Also injured are those who limit their claims of universal knowability to a limited domain. For instance, Immanuel Kant (A223/B272) asserts that all empirical propositions are knowable. This pocket of optimism would be enough to ignite the contradiction (Stephenson 2015).