posed to a
&gt; &gt; &gt; nonmathematical one), and in any case what is in a set isn't
&gt; &gt; &gt; determined by the form of the definition.
&gt; &gt;
&gt; &gt;MW: No but what things are sets is. I only mean here that to 
&gt; be a set you
&gt; &gt;must be iteratively constructed,
&gt; 
&gt; Oh no no. Consider the set of all noncomputable numbers, for example.

MW: I don't understand. I'm not hot on noncomputable numbers for a start.
&gt; 
&gt; &gt;and you can't for example have yourself as
&gt; &gt;a me