  The content of a sentence, at a context, can also be evaluated for truth at a world other than the world of the context. This is how the truth-values of sentences that contain modal operators, such as ‘possible’, are determined. For example, the content of ‘I am a philosopher’, with respect to \(c_1\), is the singular proposition that Mary is a philosopher. This proposition is true at \(w_1\), the world of context \(c_1\). But this proposition is false at world, \(w_2\), in which Mary goes into mathematics rather than philosophy. So, the sentence is true with respect to \(c_1\) and \(w_1\), but false with respect to \(c_1\) and \(w_2\). Therefore, the modal sentence ‘It is possible that I am not a philosopher’ is true with respect to our original context and its associated world, \(c_1\) and \(w_1\). Therefore, the modal sentence ‘It is possible that I am not a philosopher’ is simply true with respect to \(c_1\). (Notice that this last remark did not mention a world.)