difference between self-contradicting and self-contradictory

Do you mean mutually contradictory or just contradictory?

A self-contradictory argument contradicts itself.

Two or more arguments which contradict each other are said to be mutually contradictory.

thanks contrex.
i think you are right. it should be "this argument is self-contradictory".
but under what condition do we use "self-contradicting"? how is it
different from "self-contradictory"?
thanks a lot!

They mean the same. They are interchangeable. Use either as you wish.

"self-contradictory statement" is easier to say than "self-contradicting statement."

I would use " . . . tory" as an adjective before a noun.

and the " . . .ing" as a noun, as in "That is self-contradicting."

thanks contrex and SULLYFISH66.
and yes, SULLYFISH66, i somehow felt the same way -- at least i thought that there might be some difference under these two conditions (that's why i listed those two phrases as examples in my original post ).
thanks!

Wouldn't that be a verb, "That is self-contradicting", rather than a noun ?

1. You are attempting to revive a conversation that is five and a half years old.

2. "Self-contradicting" is not a verb; it is an adjective.