How to join two phrases sharing a common ending
One of my professors asked me if I would be working on an assignment alone or in a group. I responded by saying:
I was looking at the assignment and I feel that I am capable of, and therefore would benefit more from, doing it on my own.
The second comma feels a little out of place, yet I think it is necessary because it denotes the point at which two threads join together:
I am capable of doing it on my own.
and
I would benefit more from doing it on my own.
If I were speaking, it feels natural to pause at that point, but the comma still seems odd. Am I structuring this sentence properly or is there a better way?
Solution 1:
I've always found this a tricky question with no entirely satisfactory answer. There are two principles working at cross-purposes here:
On the one hand, a phrase or clause enclosed in commas is 'bracketed out' of the sentence, just not so strongly withdrawn as it would be if enclosed in parentheses or dashes. It's a parenthesis, a side-comment, not integral to the core sense. And this punctuation is consistent with how we speak the structure: come to a pause, lower the voice for the parenthesis, pause and resume at the original tone.
On the other hand, the syntax demands that the two parallel pieces (A-capable of and B-...would benefit more from) be clearly distinguished, and the beginning of the C-piece that concludes both be clearly marked. In speech, we do this by coming to a pause at the end of A ... continuing B at the same level, but with the final cadence springing from a higher pitch than the corresponding final stress in A ... and then pausing before resuming with C spoken at that elevated pitch. And the only satisfactory typographic device we have for making that structure clear is what looks like a parenthesis—bracketing with commas or dashes or parentheses.
When I'm uncertain of my audience's syntactical sophistication, or my B-piece is unusually long, I parenthesize (usually with commas) and put a typographic emphasis (italics or underscore or boldface) on the stressed word or phrase that terminates B.
... I feel that I am capable of, and therefore would benefit more from, doing it on my own.
In very formal writing I just bracket with commas and take it on trust that anybody who's reading the piece will be sophisticated enough to follow what I'm doing.
But that's just one writer's solution, not a 'rule'.
ADD:
And if you're not wedded to your structure, you're probably better off with rewriting, as Bill Franke says.
Solution 2:
The first thing to do with this sentence, if you plan on writing it, is eliminate the superfluous language: I was looking at the assignment and. This adds nothing of value, because how would you know that you were capable of doing it alone had you not looked at it? That fact is easily inferable.
Then all you have to say is: I feel that I'll benefit more from doing it on my own. The implication that you think you're capable of doing it on your own is included in that statement.
If you want to emphasize your self-confidence, you can say: Because I'm sure that I can do it, I feel that I'll benefit more from doing it on my own.
These aren't the only or necessarily the best sentences, but they're more to the point than the example sentence, and they're not presumptuous or boastful. The one that starts with "because" is slightly verbose, but sometimes verbosity is acceptable and even necessary.