How do I show or hide a Views block based on a boolean field in the displayed node?
Forget views. 

Go to the visibility settings for the block (under /admin/structure/block) and set the Page Visibility to only show on "Pages on which this PHP code returns TRUE".

Then check your boolean field with the following code:

$node  = menu_get_object();

return (isset($node-&gt;field_boolean[LANGUAGE_NONE][0]['value'])) ? $node-&gt;field_boolean[LANGUAGE_NONE][0]['value'] : FALSE;


Then place the block on the page where you want it.