Dear Simon,
I had thought that had been addressed, but if you missed it, here it is again. Holy Tradition depends on four pillars: Holy Scripture; the writings of the Fathers; the Liturgy; and decisions of councils recognised as Ecumenical. So, quoting ECFs, or Councils, or your own interpretation of Scripture, or of the Liturgy, are all clear signs that one is seeking to assert one's own will rather than trying to discern the will of God by listening to all the sources He has provided. We are all sinners, we all do this; this is why the Church founded by Christ relies on Holy Tradition and not an infallible man - neither a Pope, nor one individual who is convinced that his reading is correct; all are fallible, not one is righteous.
Thus, it is bound to be the case that mistakes are made. How do we know it is a mistake? Usually because whatever has been decided turns out to be unacceptable to the faithful. Thus, the various councils which approved Arian teachings were not received by most of the faithful, and by much of the Church until, in the end, St. Athanasius triumphed against even the might of the Emperors; how so? Because he, and those who supported the orthodox teaching were supported by the Holy Spirit and by the people. Their triumph has been validated by the Church ever since. We believe God is with His Church and will not let error triumph for ever. The same is true of the iconoclastic Council.
Before the Muslim invasions the Church never discussed the issue of icons. Some ECFs didn't like them, some did; but none of the Councils discussed them. In response to the Muslim puritanism on 'idols', this became an issue. It actually only became an issue for the Chalcedonian Church; the non-Chalcedonians never found this an issue, and it is interesting that it should have been a Christian working within an Islamic state, St. John of Damascus, who provided the most cogent arguments against the iconoclasts.
How do we know that the decision of the second Nicene Council was correct? Because it was received by the faithful and has been accepted by them ever since. We do not believe that God would allow His Church to dwell in the wrong for so long; if you do, you do.
No, I mean that in the Church which received the Holy Tradition, the decision remains accepted.
As we have endeavoured to explain, for the Orthodox, no one has infallibility - that's why we give our ancestors a vote. It may be that an individual reading the Bible in twenty-first century America has it all correct and that he is, in effect, personally infallible; but how the rest of us are to determine that is unclear. On the other hand, it may be that a Church which has existed from the beginning, and which has carried the Good News forward despite persecutions, despite errors of individuals, and despite the travails of two thousand years, has more of an insight into these holy mysteries.
Peace,
Anglian
