"as far as" vs. "so far as" vs. "in so far as"

Question

Are these sentences the same?

As far as I know, he's going to Chicago.
So far as I know, he's going to Chicago.
In so far as I know, he's going to Chicago.

I think that they are the same in meaning but differ in formality. I think the first one is formal, the second one is informal, and the third one is very formal.

So far as I know is slightly marked, as formal, in US English. Therefore less common in speech. Insofar as (with variable spacing) is a technical legal term. Don't use it if you aren't a lawyer. — John Lawler, Jan 29 '13 at 19:47
@JohnLawler why is insofar as specifically legal? It is archaic I grant you, but exclusively legal? Could you provide some references for that? — terdon, Jan 29 '13 at 19:52
As far as popular registers*, archaic = legal; any distinction would be important only to a lawyer or an historian. — John Lawler, Jan 29 '13 at 21:23

score 3 · Answer 1 · edited Apr 13 '17 at 12:38

As far as I know, he’s going to Chicago.

So far as I know, he’s going to Chicago.

These are identical in meaning and register. They differ only by dialect or individual speaker preference. According to Google Ngrams, they are approximately equal in popularity:

In so far as I know, he’s going to Chicago.

This is a less popular variant, which to my ear sounds slightly more formal simply because it’s wordier. In American English the spelling is insofar, meaning “to such an extent”.

score 0 · Answer 2 · answered Jan 29 '13 at 21:05

0

The first one is the most common usage in casual and even semi-formal speech/writing.

answered Jan 29 '13 at 21:05

amanda witt

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"as far as" vs. "so far as" vs. "in so far as"

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