The catholic principle - whether Fr. Hogg or Fr. Fenton coined the term, I'm not sure - in Lutheranism may be stated thus:
The Scriptures provide a negative critique on Tradition; whatever in Tradition is contrary to the witness of the Sacred Scriptures, must be rejected; whatever is not, is accepted.
The Scriptural principle - often called sola Scriptura (but that term is also used by those who reject the catholic priniple entirely) - is normatively stated for Lutheranism in the Smalcald Articles II, II, 15:
The true rule is this: God's Word shall establish articles of faith, and no one else, not even an angel can do so.
My good friend, Fr. Heath Curtis, published a critique of Fr. Hogg's paper in Lutheran Forum some years back in which he offers some thoughts on whether or not these two principles are in fact in tension. His paper is very worth reading, as also are Fr. Hogg's and Fr. Fenton's works on the topic.
I'd like to offer a further comment on the relation of these two principles and to what they properly apply. My argument is not how they *should* operate, but noting how they *did* operate in our Churches in the 16th and 17th century. Simply put:
Lutherans used the catholic principle in their critique and reformation of church practice; they used the Scriptural principle in regards to church dogma.
Obviously there is not a neat and tidy division between the two! But it is the conviction of the Lutheran Church that what the church practices should be built upon the foundation of what she teaches and be in complete harmony with the Sacred Scriptures; if anything conflicts with the teaching of Sacred Scripture in the practice of the church, it must go; if anything is not in conflict with the Sacred Scriptures in church practice, the Lutheran Church confesses that she rejoices to keep and follow such in Christian freedom. This is weight of AC XV.
[The matter of Christian freedom is a separate topic, but in sum we may note that the present Church in every place has the freedom to receive the ceremonies that have come down to her from antiquity, but that she does not receive them in the way of the law (as divinely mandated, for they are not), but in the way of the Gospel (as gifts from the Holy Spirit through the Church for her use) which she (the present church) has authority to regulate in whatever way best serves the Gospel itself in the present situation and with an eye toward the heritage of posterity; she has an obligation not just to the present generation of the Church, but to any future generations, should our Lord's glorious appearing not occur in this generation. ]
Now, my internet buddy and Roman Catholic correspondant, David Schütz has noted that the approach I suggest above leads to a breakdown of the equation "lex orandi, lex credendi." Perhaps so; but it appears to me that what I am proposing actually follows along the lines laid down by Pope Pius XII in his encyclical of 1947 on the sacred liturgy (Mediator Dei). There he insisted that lex orandi, lex credendi can and must also be inverted: "Lex credendi legem statuat supplicandi" - "let the rule of belief determine the rule of prayer." Obviously, as Lutheran, I think Pius XII was quite correct.
So, I'll throw it out for discussion: catholic principle in church practice (the application of the Scriptural faith); scriptural principle in church dogma (the content of the faith being explicitly grounded in the witness of Sacred Scripture).