I've been wondering about the Russell Paradox...<p><pre><code> S = the set of all sets not members of themselves
x = 1 / 0
</code></pre>
Isn't the problem for x the same as for S? Not all mathematical expressions are well-defined, and likewise for all "set expressions".<p>Aside: There was a wonderful quote in Jaynes' <i>Logic of Science</i>, decrying the kind of airy mathematics that Chaitin is doing...<p><i>Should one design a bridge using theory involving infinite sets or the axiom of choice? Might not the bridge collapse?</i>