It’s a long tip today. Lots of information. I’ve had a couple of people ask me about using commas, so I’ve done some research and put together this post for you.
It seems to me that there are three different schools of thought on commas. These arise from historical comma usage. The thing is commas are ruled by two things – convention and rules.
- The ‘we don’t need them’ school of thought
- The ‘use them everywhere possible’ school of thought
- The ‘modern English’ school of thought
The first group feels commas are a waste of time and ink. People in this group don’t believe that they perform a useful function at all. They suggest we no longer need to bother with what they regard as an ‘antiquated’ piece of punctuation that serves no purpose. These people omit commas even when the ‘rule’ states that a comma must be used.
The second group use commas everywhere. They fling them around and put them in, even in places where they are not needed. Even in places where they are wrong.
The third group use commas:
- Where the rules say they need them
- At other times in places where the addition of commas makes their writing easier to understand
There are not many absolute rules about commas, you will be relieved to hear. I will only discuss the main ones here – those that you are most likely to need.
Use commas to separate items on a list.
I visited Paris, Rome, Milan and Prague last summer. In this sentence some people would include a comma after Milan, and that’s okay. There’s no hard and fast rule about commas before conjunctions, although usually in UK and Australian English you would not put one there in a simple list. The exception is when the item following the word ‘and’ is a long expression. For example, ‘The team members were discussing the next quarter’s strategy, the training plan, and the proposed compensation and benefits changes.‘ The Chicago Manual of Style (2010) ‘strongly recommends’ using a comma before ‘and’ in lists because ‘it prevents ambiguity’.
These are a little like a list.
The report was well-researched, professionally written, concise, clear and thorough.
When words are put into a sentence that interrupt the flow
Sometimes we use words in the middle of a sentence that might normally be found at the beginning.
The word ‘however’ is a common culprit here. ‘My boss, however, did not agree.’
This also applies when we provide more information about something or someone within a sentence. ‘David Flynn, the deputy sales manager, did not agree with the proposal.’
With direct speech
The boss said, ‘It’s going to take far too long to complete the project if we do it like that.’
When subordinate clauses begin the sentence
If you are ever in Prague, give me a call and we’ll meet up.
(Without a comma this would be, ‘Give me a call if you are ever in Prague and we’ll meet up.’)
Before the non-restrictive relative pronoun ‘which’
This rule is as much about when to use ‘which’ and when to use ‘that’ as it is about commas. The rule is that we use a comma before the non-restrictive relative pronoun ‘which’. I can hear you asking, ‘What on earth is a non-restrictive relative pronoun?’
I’ll try and make this clear with examples. A non-restrictive relative pronoun introduces a clause that is not essential the meaning of a sentence. I am going to borrow my examples from The Elements of Style by Strunk and White (p. 59) because I think their example is very clear.
The lawn mower that is broken is in the garage. (Restrictive)
The lawn mower, which is broken, is in the garage. (Non-restrictive)
The first sentence tells us which lawnmower we are talking about. The restrictive clause defines.
On the other hand the second sentence tells us a fact about the only lawnmower in question. The non-restrictive clause only describes. And it is this one that uses a comma.
What about when the rules don’t apply?
My rule of thumb for using commas at other times is to read the sentence carefully watching out for two things.
- Are there places where you would naturally pause when reading a long sentence? If so, often a comma will help your reader. Particularly in long sentences.
- Is the meaning clear if you don’t include a comma? Lynne Truss includes some excellent examples in her wonderful book Eats, Shoots & Leaves.
Incorrect comma usage
Correct comma usage
|Leonora walked on her head, a little higher than usual.||Leonora walked on, her head a little higher than usual|
|The driver managed to escape from the vehicle before it sank and swam to the river-bank.||The driver managed to escape from the vehicle before it sank, and swam to the river-bank.|
In another example that Truss gives the sentence could be perfectly correct, but add commas and the sentence has a very different meaning.
‘The convict said the judge is mad.’ Or is it, ‘The convict, said the judge, is mad.’
So carefully read what you have written and think about whether commas will help people understand your meaning.
If you want to delve more into the delights of comma placement, Michael Swan’s Practical English Usage, provides good advice and examples. Mark Tredinnick devotes some 15 pages to its use in The Little Green Grammar Book. He too provides excellent examples and clear explanations.