Melito of Sardis for example lived in the second century. He was the first church father to list the Old Testament canon for us. He gave us a canon closer to that of evangelicalism than that of Roman Catholicism:
"I learned accurately the books of the Old Testament, and send them to thee as written below. Their names are as follows: Of Moses, five books: Genesis, Exodus, Numbers, Leviticus, Deuteronomy; Jesus Nave, Judges, Ruth; of Kings, four books; of Chronicles, two; the Psalms of David, the Proverbs of Solomon, Wisdom also, Ecclesiastes, Song of Songs, Job; of Prophets, Isaiah, Jeremiah; of the twelve prophets, one book; Daniel, Ezekiel, Esdras. From which also I have made the extracts, dividing them into six books."
(cited in the church history of Eusebius, 4:26)
I like it...Here's how he arrives at it...
"Melito to his brother Onesimus, greeting: Since thou hast often, in thy zeal for the word, expressed a wish to have extracts made from the Law and the Prophets concerning the Saviour and concerning our entire faith, and hast also desired to have an accurate statement of the ancient book, as regards their number and their order, I have endeavored to perform the task, knowing thy zeal for the faith, and thy desire to gain information in regard to the word, and knowing that thou, in thy yearning after God, esteemest these things above all else, struggling to attain eternal salvation. Accordingly when I went East and came to the place where these things were preached and done, I learned accurately the books of the Old Testament, and send them to thee as written below." (cited in Eusebius, Church History, 4:26:13-14)
Apparently, neither Melito nor the person he's writing to thought that the means of arriving at a reliable canon was an infallible ruling from a worldwide denomination led by a Pope. Instead, Melito relies on his own examination of evidence, and he refers to his conclusions as reliable.