@bob "For example, assume that an application's license states: "This program is licensed under the GPL," and includes a copy of the GPL v3 license in its entirety. Because the project did not explicitly communicate which version number of the license applies, a reasonable interpretation would be that any and all versions of the GPL published by the Free Software Foundation may apply—v3, v2, or even v1!"
This would not constitute a reasonable belief. If the version is not specified then it would be assumed in a court of law that the version included with the application is the one which governs.