The popular phrase "I'm just saying" has been around long enough for most people to have heard it, but not long enough for it to be well-documented as to where it originated. I heard a great stand up comic bit about it in the 1980's by Paul Reiser. There are several blog sites that muse over its origin and solicit theories:
It turns out that the most common definition of the phrase exhibits a logical paradox from Philosophy. The book "this sentence is false" is a collection of philosophical paradoxes, and it describes Moore's Paradox (as developed by
G.E. Moore). I summarize it as follows:
Normally, everything that can be said about the world can be said by anyone. I can say the moon is made of green cheese, and you can say it. The state of the world described by me can equally be described by you with no logical paradox...EXCEPT... I can say that the moon is made of green cheese, and I can say that you do not believe that the moon is made of green cheese, but YOU can not say the same thing. I.E. you can not say that X is true and at the same time say that you do not believe that X is true. Note that you are not saying that you could be wrong in your belief, you are be saying that you believe both that X is, and is not, true at the same time. A logical contradiction.
However, whenever you use the phrase "I'm just saying!", you are in effect performing Moore's paradox.
