'Scripture, Tradition, and Reason' often functions as a shorthand code for what Anglicanism is all about. But what does this code actually point to? I think it is generally held to mean something like this: Anglicanism is a form of Christian faith and practice which has evolved to employ reading Scripture, drawing on Tradition, and working with rational arguments, common sense, and due regard for the evolution of scientific knowledge in a balanced way when making decisions. Perhaps it is also useful to note what is generally being excluded by this way of making decisions: appeals to a pope, a magisterium (unless that be the church-in-synod/convention), or to Scripture (alone) as supreme authority (or, for that matter, to a foundational element of our heritage such as the Thirty-Nine Articles, or the BCP (1662).
At this point some minds go to bed happy in the knowledge that Anglicanism is obviously sane, sensible, and sorted. There may even be some extra satisfaction that we are 'not like' Romans, Pentecostalists, or Presbyterians!
In fact, 'Scripture, Tradition, and Reason' is a sleight-of-hand which hides a number of worrying things about Anglicanism which relies on this formula.
(1) It offers no guidance as to what might constitute a wise balance between Scripture, Tradition and Reason.
(2) It offers no parameters as to what constitutes 'Tradition' (so, for example, evangelical Anglicans might count heavily as Tradition the Calvinist influences of the 16th and 17th centuries, trumpeting the 39A as superbly representative of Anglican tradition, while anglo-catholic Anglicans might count heavily as Tradition the Catholic influences at work prior to Cranmer and later renewed in the 19th century).
(3) It offers no direction concerning the character of 'Reason': in some conversations it seems to mean rational thought mixed with common sense (which itself is interesting, because lots of non-Anglican Christians think similarly), but in other conversations it seems to mean contemporary experience of life. Indeed sometimes Anglicans become (so to speak) Methodists with fourfold talk of Scripture, Tradition, Reason, and Experience.
(4) It offers no special place for Scripture, notwithstanding the special place of honour given to Scripture through the reforming of the Church of England, the establishment of the Book of Common Prayer, and the laying down of the Thirty-Nine Articles. In the latter case, whatever their inadequacies from current perspectives (e.g. we may not want to say what they say about popes or magistrates), these Articles consistently invoke Scripture as a higher authority than Tradition. One might also note that in Anglican liturgy Scripture retains a special place (we read from it, and not from Tradition or Reason). Is it not odd that when making decisions, some Anglicans then demote Scripture to equal footing with Tradition and Reason?
(5) It offers no account of the role of the Holy Spirit in the making of contemporary decisions! This also is interesting as (in my experience) Scripture, Tradition and Reason Anglicanism is comfortable switching to talk of the Spirit leading the church into new truth. While it is possible to argue logically that it is the Spirit who guides us as we reckon with Scripture, Tradition and Reason in making decisions, it becomes quite irrational to argue (as some do these days) that the Spirit may lead us to a decision which is unsupported by either Scripture or Tradition because there is no rational basis for knowing that we are making the right decision when at best one leg of the Anglican stool (i.e. Reason) is holding the decision up!
(6) For all of the above reasons, merely invoking Scripture, Tradition and Reason as the general character of Anglican decision-making leaves the door open to the decision-makers to play each off against the others so that the decisions made actually reflect the preferences of the decision-makers. If the decision-makers are in control of the manner in which Scripture, Tradition and Reason are balanced in support of the decisions made, then the real authorisation of the decisions are the people holding power. But, conveniently, 'Scripture, Tradition and Reason' can be invoked as supporting the decisions.
Besides which, we may ask, where is the authoritative statement of a recognised Anglican authority, that Anglicanism is most truly expressed when it invokes Scripture, Tradition and Reason as the three legged stool upon which this form of Christianity is established?