It seems that "e.g." is always followed by a comma but "i.e." is not. Why is that?
The distinction probably emerges from their different meanings in Latin, which grants them different usages in writing.
E.g. (exempli gratia in Latin, meaning “for example”) should be generally followed by a list of examples. Thus, adhering to proper English style usually requires commas to follow e.g. to delimit the beginning of that list.
I.e. (id est in Latin, meaning “that is”) is used to recapture the meaning of an antecedent clause by rephrasing. Typically, it is only followed by a clause describing a singular entity, and so does not require a comma.
Grammar Girl did some research and determined that five out of six style guides lean toward using a comma after both i.e. and e.g. Here's the gist of the table she shared on her site:
- Chicago Manual of Style: A comma is usually used
- Blue Book of Grammar and Punctuation: Commas are preferable/optional
- The Columbia Guide to Standard American English: Editors require a comma
- The Guide to Grammar and Writing: The commas make good sense
- Lynch Guide to Grammar: Should be followed by a comma
- Fowler's Modern English Usage: Commas do not usually follow i.e. (No comment on e.g.)
She also gives an excellent rundown on when to use each of these abbreviations. She suggests that you think of i.e. as meaning "in other words" and e.g. as meaning "for example." I recommend reading her entire article.
Addition: My daughter just reminded me of an excellent and entertaining explanation of usage for i.e. and e.g. from The Oatmeal. This one I can't summarize. You must view it in all its glory.
I was drawn to this question by edits that I made on other SE sites, constantly being re-edited and commas being added after an "e.g." that I had added, without the comma. After the umpeenth time, I decided to check whether I was wrong, and had been making the same mistake for 40 odd years. I was quite sure that the use of a comma was incorrect and had not really seen it used before.
I liked @Kristina's answer, but still ever doubtful, I decided to follow the links provided in the answer. It turns out to be a linguistic cultural difference between American English and British English. In American English the additional comma appears to be quite prevalent, whereas in British English it is very rarely seen/used.
I've also been told that the commas are used less frequently in Britain, and the only style guide I found that advised against commas was Fowler's Modern English Usage, which has its roots in British English.
So, in short, I am happy to say that, as a Brit, I am not wrong in my refusal to add the comma, but then again, neither are the subsequent editors of the text. It just depends upon which flavour of English one uses natively. ;-)
However, ironically, after "for example" I add a comma.
In addition, for completeness, I would not use a comma after "i.e.", although I would after "that is to say".
It is not true that i.e. is never followed by a comma, nor that e.g. is always followed by a comma. You could also write sentences like the following.
Similar dynamics that resulted in the development of new local art forms have been documented elsewhere (e.g. Chibnik 2008).
My walking boots are synthetic, i.e., not leather or suede.
I am late to the party, but among all the excellent citations given in support of using or not using a comma after i.e. and e.g., let me also mention what New Hart's Rules (2005) from Oxford University mentions in the chapter Punctuation>Comma>Other uses (4.3.8):
Depending on the structure of the sentence as a whole, a comma may or may not be used after namely and for example:
The theoretical owners of the firm, namely the shareholders ...
We categorized them into three groups—namely, urban, rural, or mixed
A comma is generally required after that is. To avoid double punctuation, do not use a comma after i.e. and e.g.
I am going to go with Oxford’s recommendation of not using a comma after either i.e. or e.g. purely for aesthetic reasons.
According to Fowler's "Modern English Usage", as quoted in Daily Writing Tips, “whether a comma follows [e.g.] or not is indifferent, or rather is decided by the punctuation-pitch of the writer of the passage.” He says nothing of “i.e.”, but I go by the same idea.
A comma signals a slight pause. If I speak what I write, would I pause there?
I think it’s clear that e.g. has to have full stops/periods. As for using a comma after it, that should only be done in some rare cases, as in the sentence “e.g., i.e., and other abbreviations of Latin forms are often a source of confusion for English learners.” In other cases, I can see no logical reason for it to be used except a puzzling convention followed by some writers. As for convention, style guides typically don’t recommend this. Why not follow logic rather than convention, or if you follow convention, follow all major style guides, which use e.g.? I recently wrote a blog post on this issue at http://www.makeyourenglishwork.com/2012/05/17/eg-or-e-g/ if you’re interested.
I think we will usually use a comma. We can confirm the same by substituting the abbreviation with original word, i.e., with "For example" and "That is" in this case. E.g.:
I like you, that is, I think I like you.
Although I am not sure what will be case if the sentence ends with e.g. or i.e.
- I think I will die soon. I did not do anything in my life. But still it might not be a complete waste, i.e. (e.g.)...
- I think I will die soon. I did not do anything in my life. But still it might not be a complete waste, i.e. (e.g.),..
The first one seems correct to me.