&gt; The concept of prime numbers and the prime numbers themselves is a different thing.<p>I&#x27;m okay with that, and haven&#x27;t said anything suggesting otherwise. However, if you want to reject the existence of mathematical objects in the real world, you have to reject the existence of mathematical definitions too, because mathematical definitions are mathematical objects just like any other. So, if the definition of “prime number” doesn&#x27;t exist in the real world, then any statement about prime numbers is meaningless in the real world.<p>&gt; Unicorns don&#x27;t exist but statements about them aren&#x27;t meaningless.<p>Unicorns don&#x27;t exist in the real world, but the <i>definition</i> of “unicorn” does - just grab any dictionary. It&#x27;s on the basis the existing definition that you can say “unicorns don&#x27;t exist”. On the other hand, you may reject the definition of “horse”, but, if you don&#x27;t, you have to accept that horses exist in the real world. And, if you do reject it, then you also have to reject statements about horses as completely meaningless.<p>&gt; Fictionalism accepts the concept of mathematical entities but denies their existence in the real world.<p>The question of whether mathematical objects exist in the real world is ill-posed in the first place. It&#x27;s like asking if love can be stored in boxes.