It can be used intransitively.
Have a look at the example sentences in the link below.
You'll also find plenty of instances of "ponder" + "over" in the Corpus of Contemporary American English as well as in the British National Corpus.
I disagree. I think that dictionaries and corpora list examples of natural usage of a word/phrase. That such usage may or may not not make sense to some of us is an entirely different matter.Dictionaries are generally interested in giving evidence of usage, whether the usage makes sense or not.
This descriptive approach is even more apparent with corpora, (from which most dictionaries take their examples) which will show all kinds of erroneous language use, regardless of how egregious.
There may or may not be a reason, but the fact is such usage exists and is common enough!My argument is that if
- to ponder the meaning of life
- to ponder over the meaning of life
express the same thought, then why the grammatical difference?
I think that dictionaries and corpora list examples of natural usage of a word/phrase.
the fact is such usage exists and is common enough!
perhaps "over" is used for some kind of emphasis here - in the same vein as "mull something over" or "go over something"; with the preposition "over" intimating that you scan/examine that thing thoroughly.