How did John Duns Scotus connect Mary’s Immaculate Conception with Christ’s redemption?

John Duns Scotus addressed the concern that the Immaculate Conception might conflict with the doctrine of Christ’s universal redemption by proposing that Christ’s redemptive grace could function in a preventative, rather than merely curative, manner.12

He argued that through a special intervention of divine grace, Christ’s redemptive power was applied to Mary at the first instant of her conception to prevent original sin from ever reaching her soul. By framing this as a "perfect mediation," Scotus maintained that Mary’s preservation from sin was not due to any intrinsic merit of her own, but was a direct result of Christ’s superior redemptive act, which he considered a more perfect form of redemption. This defense became a turning point in the history of the doctrine, effectively reconciling the belief in Mary's sinlessness with the necessity of universal redemption through Jesus.12