for one is an idiomatic expression, used mainly in the form of " I, for one" meaning:
that you think your opinion or action is right, even if others do not:
- The rest of you may disagree, but I, for one, think we should go ahead with the plan. (Cambridge Dictionary)
Its usage appears to date back to the second half of the 18th century, the following example is from
... they are such that I, for one, shall not believe any lawyer capable of advising such proceedings.
My question is about the usage of for, how it became idiomatic in the expression "I, for one". The meaning could be conveyed saying, "I, as one", or "I, being one" for instance, so how did the expression form? is it the short of an archaic originally longer expression? What's the meaning of for in "for one"?