  A further question is whether actual peer disagreements are the only peer disagreements with epistemic significance. For instance, suppose that you have created an argument that you find sound in the solitude of your office. When thinking about what your (peer) colleague would think, suppose that you reasonably conclude that she would disagree about the merits of your argument. If such a conclusion is reasonable for you, then it seems that this fact should have some epistemic consequences for you despite the fact that there is not (at least as of yet) any actual disagreement. Arguably, such a merely possible disagreement even has the same epistemic significance as an actual disagreement (see Carey &amp; Matheson 2013). Similarly, if an evil tyrant believes \(P\) and then chooses to eliminate all disagreeing peers who believe not-\(P\), he would not thereby become justified in his previously contentious belief (Kelly 2005). A challenge is to pick out which merely possible disagreements are epistemically significant, since at the risk of global skepticism, clearly not all are (Barnett and Li 2017). Issues surrounding counterfactual disagreement are also examined in Ballantyne 2013b, Bogardus 2016, and Morgensen 2016.