I recall stumbling upon a linguistic feature more common to native American languages called grammatical evidentals, where certain statements required some sort of marker which indicates how the information is known to the speaker: whether by direct experience (I saw the rain), or hearsay (I was told it's raining), etc.

I have considered on occasion that this would be useful, as a great deal of internet arguments stem from the fact that English allows for the construction of sentences which state subjective experience as absolute truth.