I seldom agree with PA on certain issues, but I do agree that the primary source is the Qur'aan. I'm sure the majority of Muslims also agree with this notion.
As long as 'early scholars' do not condradict the Qur'aan, then we don't have a problem. However, we cannot just rule out the scholars opinions merely on the basis that they did not have the advanced technology that we do today, in order to clarify scientific issues. Science is always moving.
For example, the Qur'aan mentions prior nations which were gifted in architecture and some of their finds are still unmatchable. They did not have the tools of today, but still advanced.
The english language is not in the same format as it was even as late as the Victorian era, but we still use the language in it's current form.
Scholars took time out to study in the past and maybe we should also take time out to ponder and study. The point here is that the Qur'aan was always at the top, and all subsequent opinions and rulings were derived from the Qur'aan.