Is there a Capability that checks as true for non-logged in users?

by 

if ( is_user_logged_in() ) {
 // your code for logged in user 
} else {
 // your code for logged out user 
}

or perhaps…

$current_user = wp_get_current_user();

…specifically:

<?php
 $current_user = wp_get_current_user();
 if ( 0 == $current_user->ID ) {
  // Not logged in.
 } else {
  // Logged in.
 }
?>

…might lead the way?