Full Idea
The real problem of pure reason is contained in the question: How are synthetic judgments a priori possible?
Gist of Idea
The real problem of pure reason is: how are a priori synthetic judgments possible?
Source
Immanuel Kant (Critique of Pure Reason [1781], B019)
Book Reference
Kant,Immanuel: 'Critique of Pure Reason', ed/tr. Guyer,P /Wood,A W [CUO 1998], p.146
A Reaction
If they are possible, I would say that is not 'the real problem of pure reason', but the real problem of understanding the underlying nature of reality. I doubt whether we know much of reality by 'pure' reason, but we might 'see' that it is necessary.