Consider the following sentences:
- The current president of the United States has 2 daughters.
- The current president of the United States has 5 sons.
- The current emperor of the United States has 12 children.
- The current ruler of the Unites States is a blue dragon.
- The current cheddar of the United States has polynomial engines.
1) is a true statement (As of March 2015). 2) is not true, but could have easily been true if the 2012 elections had a different result. 3) is not true, and is very unlikely, but it doesn't violate the laws of nature, and is possible in some far fetched alternate reality 4) is not true and could never happen in reality, but is still a meaningful sentence, and could happen in the context of fantasy or sci-fi story. 5) doesn't make any sense what so ever, even though it is grammatically correct.
From a formal logic point of view 1) is true and 2)-5) are all false. Yet it seems to me that 2)-5) are on different ontological levels when it comes to how 'false' they are
My question is: Is there a formal way of classifying these falsehoods and has this been treated by any notable philosophers?