Experts musicologists believe that Beethoven wrote his last piano sonata in 1824, three years before his death. However, the manuscript of a piano sonata was recently discovered that bears Beethoven's name and dates from 1825. Clearly, the experts are mistaken because, not every piece that Beethoven wrote was catalogued in his lifetime, and it is known that Beethoven continued to compose until just weeks before his death.
The reasoning in the argument is most vulnerable to which of the following criticisms ?