Full Idea
Wolff believed that the principle of sufficient reason could be derived from the principle of contradiction, for there would be a contradiction in the insufficiently determined existence of a merely possible thing.
Gist of Idea
Sufficient reason is implied by contradiction, of an insufficient possible which exists
Source
report of Christian Wolff (works [1730]) by Christine M. Korsgaard - Intro to Ethics, Politics, Religion in Kant 'A child'
Book Reference
Korsgaard,Christine M.: 'Creating the Kingdom of Ends' [CUP 1996], p.5
A Reaction
Sounds as if he might be begging to question. You would only protest against the insufficient determination of something if you already believed in the principle of sufficient reason. Nice try.