Apersuasive speech exploring the truth or falsity of an assertion is known as

A persuasive speech exploring the truth or falsity of an assertion is known as speech on a question of fact.

It is known as a speech on a question of fact.
Facts are pieces of information which are always true - so if you want to determine whether an assertion is true or false, you will first have to determine whether it is a fact. If it is a well-known fact, then it must be true. Facts deal with the truth or falsity of various pieces of information.

Currently, as of february 2016, an american traveling in france would be by the exchange rate. the weakness of the euro and the strength of the us dollar means that items in france cost less to an american than they otherwise would. of course, if this trend reverses and the us dollar weakens and the euro strengthens, such as was happening in early 2008, an american traveling in france would have an adverse experience because items would cost relatively more.