General Gonzales' lies

On the Washington Journal of July 26th, 2006, Attorney General Gonzales told a lie. He stated that he does not need a warrent to make a search, if the search in reasonable. This statement is either a lie or the Attorney General is a very bad lawyer. The Forth Ammendment to the constitution of the United States reads:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

Now let us assume that the General is correct and that no warrent is needed if a search is reasonable. This does seem to be what the 4th ammendment states right there in the phrase: secure ... against unreasonable searches and seizures. But now lets think of why the Founding Fathers put in that second sentence if warents aren't needed unless a search or seizure is unreasonable. It must be there for those cases where the search is unreasonable, right. But if that is the case then why require oath or affirmation and probable cause to be required for a warrent to be issued? Isn't this a statement of what is required for a search to be reasonable? This seems like the only choice though. Unless we assume that a warrent is only required if a search is unreasonable.