 If we ignore time, we can think of the meaning of “I am sitting” as a function from pairs of speakers and worlds to truth-values. Suppose Moe is sitting in the actual world w and standing in alternative world w′, while Curley is standing in w and sitting in w′. “I am sitting” is true at &lt;Moe, w&gt; and &lt;Curley, w′&gt;.