When "Just because," is not a satisfactory answer.

Why can't a prepostional phrase be a subject complement? A question I have been trying to answer for months.
This is from A Student's Introduction to English Grammar, which is an abridged version of The Cambridge Grammar of the English Language. I am paraphrasing as the language is quite technical.

Prepositional phrases cannot be subject complements (a predicate adjective or predicate nominative). It does not matter if they are adjectival or adverbial. A complement must be licensed by the verb, meaning the complement can only occur with a certain type of verb that allows it. For a subject complement, this type of verb is a linking verb.

Here are some examples:

She is pretty. You cannot substitute a transitive or intransitive verb here: She ran pretty (Vi), She enjoyed (Vt) pretty. Neither work here. Pretty is a complement in this sentence, because you must have a linking verb in order for the sentence to be grammatical.

The book is about birds. You can substitute an intransitive: The book teaches about birds.

Jesus was about His Father's business. Jesus was learning about His Father's business.

She is from Nebraska. She comes from Nebraska. She walks from Nebraska.

She is in the woods. She sits in the woods. She walks in the woods.

She is in a hurry. She came in a hurry. She left in a hurry.

A word or phrase is only a subject complement if it requires a linking verb. If you can substitute any other type of verb, it loses its status as a complement.

Can weigh be a linking verb?

Here's the sentence: The roast weighs four pounds.

Is the word weigh a linking verb?

First, let's consider the other option:

Weighs is an intransitive verb and four pounds is an adverb telling how much to roast weighs.

When a verb is modified by an adverb, it describes the action being done by the subject. Since the roast is not doing any action,  four pounds cannot be adverbial. If there were action here, then the verb would be transitive and not intransitive since it is followed by a noun. That is, four pounds would become the direct object. If this is confusing, consider this sentence: The butcher weighs the roast. Here, weighs is a transitive verb and roast is the direct object.

So, yes, in this sentence, weighs is best classified as a linking verb. Four pounds is an attribute of the roast. It is a four pound roast.

The End Is Here

"The end is here."

could just as easily read...

"Here is the end."

One of the criteria of a predicate noun is that you can replace the subject with the predicate noun and it still makes sense. But, what are the other criteria? Here cannot take an article, like most nouns, so there is one strike against it already.

In the sentence“here is the end” one could argue that “here” is an expletive, not the subject, (like “there is the end”—you would diagram it with "there" above “the end | is”). The focus, when “be” is followed by an adverb, like now, here or soon is the existence of the end, much like I am using it here: It is inevitable that the end will be, it’s just a matter of when it will be. Here, I will concede that "is" could be an intransitive verb modified by an adverb.

However, this is not the same focus in a sentence like: The girl is in the kitchen. The question being answered is not whether or not she exists.

Here is what I woke up thinking about:

I painted the chair in the corner – If “in the corner” is adverbial, then it means that I sat in the corner and painted the chair. If it is adjectival, then it means that I painted the chair that is in the corner.

In the relative clause – that is in the corner – there is no question in my mind about what “in the corner” modifies, it is telling which chair by telling where the chair is. If you diagrammed it, you would make a dotted line from “that” to “chair”. If you replaced the pronoun with its antecedent, you would have: The chair is in the corner. (I have a math brain—it would be nice if I could plug in numbers to prove my point).

Like math, in grammar, it does not matter if you have 2 apples or 2 oranges it's still 2. Semantics do not determine grammatical function—meaning it is not fair to say “She is in the kitchen” really means “she is doing something in the kitchen” therefore “in the kitchen” is adverbial.

Think about common mistakes people make with linking verbs: I felt badly about the situation. They want to use the adverbial form of “bad” because it tells how they felt. (I am thinking of the time Donald Trump scathed Cyndi Lauper on national television for saying “I feel bad”. He argued that it should be “badly” and he is highly educated.)

{I am leaving the rest of my post here because I am blogging to document my learning process. But since I do not want to lead anyone astray with my former ignorance, here is a link to more accurate information: http://livefullyawake.blogspot.com/2011/11/when-just-because-is-not-satisfactory.html}

Why do we ask “How are you?” but have to answer with “what are you?”

Why would we let words that describe how I feel, look or seem be adjectives, but not words that tell where or when something IS? And why when there is a choice, why do we choose an adjective every time? Or if there is an adjectival equivalent, we can substitute it?

South Dakota and Montana are beside each other – They are adjacent or adjacently?

New York is in the north – New York is northern.

Makes You Think

I considered creating a new blog to feed my obsession with English grammar, but I realized that to think about these things deeply is to live fully away, so I will just post it here and put a grammar tag on it.

Before you read this post in entirety, consider how you would classify this sentence: The performance and the party are at the same time.
How would you classify "at the same time?"

I have been obsessed with whether or not a prepositional phrase of time or place is adjectival or adverbial when following "to be". Consider this:
If you were going to substitute a word for “at the same time” would you use simultaneous (an adjective) or simultaneously (an adverb)?

If "at the same time" can describe the compound subject in this sentence, is it a big leap from this to classifying "Tuesday" as adjectival in this sentence: The performance is Tuesday.

The options we have for the verb here are 1. it is a linking verb or 2. it is an intransitive verb.

If Tuesday is adverbial, then the verb cannot be a linking verb.

If "is" is not linking "performance" to "Tuesday", then what is it doing in this sentence? To say, "The performance is", is just to say "there is a performance". The purpose of this sentence is to say something more about the performance.

I anticipate that many will reply that what the sentence really means is: The performance and the party will happen at the same time. Here, "at the same time" modifies will happen, making it an adverb.  But, this is not a semantic question, but a grammatical one. And who talks like that anyway?

I am not married to this idea that all prepositional phrases following "be" are adjectival, but we have a serious courtship going on.

I could be missing something obvious which I have done before, so I appreciate your thoughts.