There is a second justification for patents that often gets overlooked: in order to patent an innovation, you have to exactly describe that innovation, and this

There is a second justification for patents that often gets overlooked: in order to patent an innovation, you have to exactly describe that innovation, and this discription is made public, and after the patent expires everyone is free to use it. Without this, there would be a strong incentive to keep innovations secret as much as possible, which may have them end up being lost.