Except that it wasn’t formal logic; the conclusion didn’t follow from the premise, because there’s nothing indicating that sickness is something which should be avoided. Therefore, the reader is expected to use information contextual to the world the author is in; namely, that sickness is bad, and should be avoided. Because there’s also another possible world where -diseases- are good, and the construction wouldn’t even make sense.
Except that it wasn’t formal logic; the conclusion didn’t follow from the premise, because there’s nothing indicating that sickness is something which should be avoided. Therefore, the reader is expected to use information contextual to the world the author is in; namely, that sickness is bad, and should be avoided. Because there’s also another possible world where -diseases- are good, and the construction wouldn’t even make sense.