For a type of &quot;an object&quot; or &quot;a value&quot;, null is wrong.<p>For a type of &quot;maybe an object&quot; or &quot;maybe a value&quot;, null is not wrong.<p>There is nothing fundamentally wrong with letting null exist in some form, especially if you hide it behind an Option&lt;&gt; interface.<p>The problem is when people use the wrong type.<p>&gt; Surely it is true or false, but not null. Otherwise you surely have the wrong type?<p>Nullable boolean is not the same type as boolean.  Problem solved.<p>The deep sense of wrongness is probably because so many languages force you to use nullable objects even when that&#x27;s the wrong type.  Not because nullables are inherently nonsensical.