But who does the job of judging? In this case, it is not Obama, the subject of the main clause. Grammatically, 'judged' is better. But my teacher said that since too many people use 'judging' now, it is deemed as correct English, and the grammarian has regarded it as a preposition so that it can be used regardless of what the subject is in the main clause.
Judging from what he did, I think he is a nice person.(I do the job of judging.)
Judging from what he did, Obama is a nice person. (It could mean Obama does the job of judging, which is probably not meant by the person who says that.)
***** NOT A TEACHER *****
Hello, LiuJing.
(1) Yes, I believe that your teacher is correct:
Nowadays some of those so-called dangling participles
(such as "judging" ) are, indeed, considered "prepositions."
(2) By the way, I found the Style Guide of The Times newspaper
(London) online. As you know every important newspaper has a guide,
which is a book that tells its reporters how to write correctly.
(a) The Times is very strict. Here are its three examples:
Good > TO JUDGE from the film, the country is in a mess.
Good > JUDGING by the film, WE can conclude that the country is in a mess.
Bad> JUDGING by the film, the country is in a mess.
(The Times did NOT use the words "good" and "bad." That's only my idea.)
(a) As you can see, The Times does not like the last example because
it is dangling. That is, there is no noun for "judging." Of course, the
"country" is not judging. But the second sentence is "good" English.
And the infinitive in the first sentence is also fine. I believe, however,
that many people would easily accept the third sentence and just call
it a preposition. Nevertheless, if you wish to do university-level writing,
you might consider following the advice of The Times, which -- as you
know -- used to be the most powerful newspaper in the world.
***** Thank you *****
P. S. I have just checked my copy of A Dictionary of Modern American Usage (Mr. Bryan A. Garner), which many writers use. He agrees that participles such as "judging" are "acceptable danglers" that comment on the following information.
His example:
CONSIDERING how hated [I have deleted the man's name] was, it is incredible that another owner would want him as a head coach.
In other words, "Considering how hated Mr. X was" is a comment on
"It is incredible that another owner would want him as a head coach."