The mathematical word plus has added various functions to its set since entering English from Latin in the 16th century. It can be a noun (statistical ability is a plus), a preposition (one week plus a day or two), an adjective (it’s plus 30° outside), and a conjunction (cycling’s a great way to stay fit, plus it’s good for you).
The last of these, used at the start of a sentence or independent clause and often followed by a comma, may also be described as an adverb (Plus, I wasn’t sure if you’d be there); authorities differ on the categorisation. The usage is controversial, receiving “considerable adverse comment” (MWDEU) and causing “widespread ripples of dismay among purists” (Robert Burchfield).
This plus has been around since the 1950s–60s, appearing mainly in speech and informal writing. The OED labels it colloquial, which is enough to make many people think there’s something wrong with it. According to the American Heritage Dictionary (5th ed.), however:
The use of plus introducing an independent clause has long been considered infelicitous, if not wrong. But a clear majority of the Usage Panel accepts it. In our 2009 survey, 67 percent accepted the example He has a lot of personal charm. Plus, he knows what he’s doing.
The AHD Usage Panel is not known for being lax about such things. Similarly, the Columbia Guide to Standard American English (1993) finds that conjunctive plus, though limited mainly to conversation and other informal contexts, is standard; as a sentence adverb it’s informal and conversational only.
A search for sentence-initial plus on the Corpus of Contemporary American English returned this graph, which shows both how its distribution is weighted towards the less formal registers of speech and magazines, and also that its occurrence has increased noticeably even over the last couple of decades (click to enlarge):
As a relatively new usage, conjunctive plus is bound to attract negative attention. The excellent Copyediting.com newsletter of Oct.–Nov. 2013 (requires subscription) has a useful article by Mark Farrell on editors’ attitudes to it: “Additional Conjunction Creates Division Among Editors”. Many of my tribe, it turns out, are set against it.
One editor said she “[didn’t] like the idea” of using plus at the start of a sentence because it was “confusing” (because less recognised). Another had never heard anyone say it, but associated it with “poorly written text”. A third said sentence-initial plus would “sound like a non-sentence”. Others were less disparaging and dismissive.
Farrell had emailed me for reaction, and in his conclusion agreed with my let’s-wait-and-see take on it. Here’s the relevant section from his article:
Stan Carey, an editor from Galway, Ireland, sees the increased appearance of plus at the beginning of a sentence as a sign of the language’s vitality. “I think it’s fine in casual contexts, but it tends to be avoided in more formal prose. Given that some people still object to sentence-initial and, it’s not surprising that a similar use of plus – a much more recent development – attracts criticism. It’s too new to be accepted at all levels, but as a grammatical innovation it signifies a language in good health.” Carey has written more about the subject at the Macmillan Dictionary Blog.
Why does this matter?
Editors’ work is mostly invisible to the public; like sports referees, we’re noticed more when we do a bad job. One aspect of editing is keeping formal written registers free of colloquialisms. So you don’t tend to see intensive literally in formal texts unless the word itself is being discussed or it’s used ironically or in quoted speech. But that doesn’t mean this use of literally is “wrong”. It’s just not appropriate in those contexts.
Plus, the proscriptive mindset gets extended beyond its natural limits. Many people, not just editors, conflate formal with normal (it’s anything but) and censure informal usages in informal domains. Not only is this a waste of time, it also betrays a value judgement without basis in linguistic fact. That formal varieties of English are intrinsically superior is a misconception best disowned.
Collectively editors help regulate standard English – itself a variegated and ever-shifting group of dialects – but we often disagree about what should be regulated and why. The that/which rule, for instance, survives largely through the work of editors who consider it important (I think the rule is unnecessary and counterproductive).
Using plus to open a sentence or independent clause is common and becoming more so. It may feel too casual for elevated writing, and that’s fine: if you’re editing and you think you should keep it out, do. But bear in mind that its status may change – this often happens – plus there’s nothing actually wrong with it.