Some resources on the internet and elsewhere treat while, whilst, and whereas as coordinating conjunctions in some situations at least, like when they introduce adverb clause of contrast. Examples:
Her brother is messy, while she is organized.
A fool expresses his annoyance to an insult immediately, whereas a wise person ignores the insult.
A reason given for considering them as coordinating conjunction (or coordinator) is that they can be replaced by coordinating conjunction but. (If you replace while and whereas in the above sentences with but, meaning will remain the same.)
This post argues that while, whilst, and whereas are not coordinating conjunctions (or coordinators).
A word has to fulfil six criteria to be considered a true coordinator. (The analysis under six criteria has been covered later in the post.) If it fulfils less, it can still be considered a coordinator, but the more it fulfils, the stronger is its claim at being a coordinator.
Of the seven commonly recognized coordinators (For, And, Nor, But, Or, Yet, and So – also called FANBOYS), only and and or fulfil all six, earning the right to be called true coordinators. On the other extreme is for, which fulfils only three. For that reason, some grammar books in fact consider for a subordinator. You may read this analysis in the post Are FANBOYS truly coordinating conjunctions?
To know if while, whilst, and whereas are coordinators or not, we’ve applied the six criteria to them, getting only two fulfilments. The result – worse than three clocked by for and equal to two clocked by most subordinators – leads to a safe conclusion that the three are not coordinators. Successful replacement by but under certain conditions doesn’t make them coordinators.
Here are the six criteria applied to while and whereas, with only first and third resulting in fulfilment. (Each criterion has been mentioned as heading.) Since whilst functions the same way as while, it has not been included in the analysis below.
1. A coordinator is positionally fixed in front of its clause.
While and whereas satisfy this condition of being a coordinator:
While she is organized, her brother is messy.
She is while organized, her brother is messy. [Incorrect: while can’t occupy any other but the front position.]
A fool expresses his annoyance to an insult immediately, whereas a wise person ignores the insult.
A fool expresses his annoyance to an insult immediately, a wise person whereas ignores the insult. [Incorrect]
2. The clause beginning with a coordinator can’t be shifted in front of the previous clause.
The clause beginning with while or whereas can come in front or back, implying the two don’t satisfy this condition of being a coordinator:
My sister prefers watching movies, while I enjoy reading novels.
While I enjoy reading novels, my sister prefers watching movies. [Since the clause can be shifted to the front, while doesn’t fulfil the condition of being a coordinator.]
The newer version is more affordable and efficient, whereas the older model was more expensive.
Whereas the older model was more expensive, the newer version is more affordable and efficient.
If we replace while and whereas with a coordinator such as but, flexibility in moving the clause around won’t work:
She wanted to go to the concert, but the tickets were sold out.
But the tickets were sold out, she wanted to go to the concert. [Incorrect]
3. A coordinator cannot precede another coordinator.
While and whereas satisfy the condition of not allowing a coordinator immediately before them. In other words, they satisfy the condition of being a coordinator:
His friends were out enjoying the weekend, and while he studied for the exam. [Incorrect. Since a coordinator (and) can’t precede while, while satisfies this condition.]
She enjoys the cold and snow, and whereas most people prefer warm weather. [Incorrect]
4. A coordinator can join units other than clauses.
While and whereas don’t satisfy this condition of being a coordinator. They can’t join words or phrases or predicates, like and or but can as shown in these sentences:
They bought coffee and donuts from the café. [and can join two noun phrases, but while and whereas can’t.]
I tried my best but couldn’t solve the problem.
She studied all night yet felt unprepared for the exam.
5. A coordinator can join dependent clauses.
While and whereas don’t satisfy this condition of being a coordinator. They simply can’t join two dependent clauses, like and, or, or but can as shown in these sentences:
They visited the museum that houses ancient artifacts and that offers guided tours. [and can join two dependent clauses, but while and whereas can’t.]
You can go if you finish your homework or if your parents give you permission.
6. A coordinator can join more than two independent clauses.
The two don’t satisfy this condition of being a coordinator, like and or or can as shown in these sentences:
You can stay home, or you can go to the park, or you can visit a friend.
He went to the store, and he bought some groceries, and he prepared dinner.
