The fusion of equal protection and due process has attracted significant attention with scholars offering varied accounts of its purpose and function. Some see the combination as productive, creating a constitutional violation that neither clause would generate alone. Others see the combination as merely strategic, offered to make a claim acceptable at a particular historical moment but not genuinely necessary. This Article offers a third alternative. Judges have and should bring both equal protection and due process together to learn what each clause independently requires. On this Epistemic vision of constitutional fusion, a focus on equality helps judges learn what rights are truly fundamental, and a focus on who lacks fundamental liberties helps judges learn which groups need the special protection of heightened review under the Equal Protection Clause.