What does a historian do when he or she points out problems with an argument?

The historian makes a rebuttal / counterclaim

Explanation:

Refutation is finding the error in a general argument and explaining the same through the use of quotations, reasons or evidence.

The refutation is a statement, an affirmation, which has the following logical structure:  

From a Hypothesis (= H) can be inferred Conclusions (= C)

and if these Conclusions are not given (¬C)

then the Hypothesis is not given either (¬H)

the virginia plan called for three branches of government and two houses of congress. representation in each house would be determined by population. the new jersey plan called for three branches of government and a single house of congress. each state would have an equal vote.