What is the part of the speech of “But” in this sentence?

Question

But the reasonableness of this command to obey parents is clear and easily understood by children, even when quite young. 

(The word “But” is a start of the sentence according to the sentence above, so that is why I capitalized it. “Reasonableness” is a noun, so should it be preposition or conjunction? Because “but” could be preposition or conjunction...) For me, I think it is a preposition...

Answer 1

Aaron makes a very good point that this sentence, to make total sense, should have more context -- sentence that precedes it to make that "but" necessary. You need something, some point, to make a "but" to follow it.

We see coordinating conjunctions like "but" beginning sentences all the time in English, especially in more informal contextsm which is most of English. You may encounter teachers and disciplines where it's not encouraged to begin sentences with coordinating junctions (FANBOYS = for, and, nor, but, or, yet, so). In this above example, you might swap out "On the other hand," for "but" and that wiould make the sentence more academic writing-fiendly.

"But" is a preposition, but rarely, and it's meaning is "except for": "everything but the kitchen sink."

Answer 2

Hello Carmilla,

This is an excellent question. You are right to note the awkward placement of "but" at the beginning of the sentence, since "good grammar" usually dictates that complete sentences should avoid conjunctions like "but" or "and" at the start. I also get your confusion with how "but" fits in with "the reasonableness," which is, as you point out, a noun. For this situation, even though we don't have a previous sentence to go off of, it can be assumed that the topic of this sentence is related to some sort of previous one, or the word "but" at the beginning would be completely redundant. Now, keep in mind that prepositions are words that show location - in, out, on - while conjunctions are words that join phrases or clauses. Think FANButOYS. So, with this, think about what function the word "but" is performing most in this sentence, assuming that a previous sentence before this one existed. I hope this has been helpful. Have a nice day!

-Aaron W.

Answer 3

The word ’but’ can, also, be used as a noun and adjective. In this case the sentence begins with a noun phrase - (But the reasonableness of this command), to obey parents, (is)clear and easily understood by children, even when quite young. 

And ’is’ is the verb.

Answer 4

In this sentence, but is used as a conjunction. Typically we use but as a conjunction to separate two ideas, two clauses in a sentence like this: I like chocolate, but my brother likes vanilla. OR I wanted to sign the contract. But my husband wanted to read the fine print first.

But can be used as a preposition to mean except, apart from. It is used to introduce the only thing or person that the main part of the sentence does not include. It is often used after words like everyone, nobody, anything, anywhere, all, no, none, any and every. For example, "He eats nothing but ice cream." (He eats nothing apart from/except ice cream).