 It is one thing if our planning for tomorrow’s sea battle is rendered pointless by the fact that, as it turns out, there will be adverse winds that prevent us from rowing out to fight the enemy. The rational coherence of planning is not threatened by the fact that sometimes the pre-conditions for our plans to be set in motion do not eventuate. That’s just life as a human being. It is quite another if our deliberations are pointless because it is impossible that there should be a sea battle tomorrow. People who waste their breath debating what to do if 2+2=5 tomorrow seem to be irrational. After all, it is impossible that 2+2 should equal 5 – tomorrow or any day! So what then would we say if we were persuaded that all alternatives to what will actually happen in the future are similarly impossible? This would seem to pose a real threat to the rational coherence of planning.