What was the purpose of keeping the discussions within the constitutional convention a secret?

The correct answer is:  

To revise the Articles of Confederation.  

The delegates’ biggest concern was that if the press leaked their discussions to the public, it would portray a fragmentary and misleading idea of what they were trying to achieve. Therefore, the convention delegates agreed to shield themselves from the publication of their proceedings by voting to hold those actions a total secret from all outsiders, including the press.