ive conception lies in its safe means of 
&gt;"forming" collections -- so safe, in fact, as to prohibit the formation of

&gt;any collection that is not a set. That is why some people regard the 
&gt;iterative conception as better suited to denying the existence of proper 
&gt;classes than to (affirming their existence and) distinguishing them from 
&gt;sets. I'm not sure whether Chris really believes in proper classes, but I 

&gt;should mention, for what it's worth, that some people who believe in them 

