Brad East argues that historical Protestant theological claims often overreach, giving as an example the assertion that the traditional five solas logically imply each other. “Any of them might be true—all of them might be true—but irrespective of that question, each principle requires independent demonstration; the solas are not necessarily a package deal.” I think Brad overstates things, and that the solas mostly imply each other as a package deal. A couple of thoughts on the outset before I make my friendly case. First, no magisterial Reformer or Reformed church ever distilled Protestant theology into the five solas or expressed them as a foundational unit. The arrangement of the five solas came centuries later in order to categorize a simplified essence of Protestant thought. Second, the definitions embedded in the terms matter. The solas are slogans, not dogmatic categories, and depending on the definitions used different conclusions are going to be reached about their logical necessitation.

Alright, so the foundational sola is Solus Christus, namely that Christ in his person and work alone sufficiently accomplished all that is necessary for salvation. This sola is not just that Christ is the single savior, but that who he is and what he did alone saves. The Reformers argued that we are justified by the person and work of Christ alone. That logically requires that no other person or activity justifies, saves, or contributes to that salvation in any way

Christ in his person and work alone are what saves/justifies
Any other ground for salvation/justification is in addition to Christ’s work
∴ Salvation/justification is by Christ’s work (grace) alone…