I have this sentence:
the president thought that sally is a sandwich.
It's supposed to be grammatically correct. But isn't that mean that this sentence is also grammatically correct:
sally is a sandwich
Can you say that in English?
president is a tool (same structure)
Sally is a sandwich.
Correct grammar. Subject "Sally", verb "is", complement "a sandwich". Sally is a name and must have a capital letter.
The president is a tool.
Correct grammar. "President" (in this sense) needs a determiner, such as "the". "The" is the first word of a sentence and the first word of a sentence must have a capital letter.
And so "The president thought that Sally is a sandwich." is correct grammar. The word "that" is a conjunction, and it forms the "think that..." pattern for reported thought. Sally is a name and must have a capital letter.
Advice: Don't use meaningless sentences like "Sally is a sandwich". Instead use: "Sally is a woman" or "The President is a woman." Language is about communication and the meaning of a sentence can guide the grammar, just as grammar gives a sentence meaning; so meaningless sentences like "Sally is a sandwich" can confuse you. Here it is confusing because sandwiches don't have names like "Sally".
If these examples came from a book, and they contain "sally" without capital letters, then the book should be discarded. It contains mistakes in basic English spelling and is probably useless for learning English. There is a rare word "sally", it means to make a sudden counterattack from a besieged fortress, it would be ungrammatical here.
I do not view punctuation and capitalization as technically part of grammar because they do not even exist in the spoken language. They are conventions of formal writing specified in style guides. According to those conventions, the spelling “sally” is an error if it is intended as a proper name. However, I believe that, if “sally” is intended as a proper name, then
The president thinks sally is a sandwich
is grammatical because it follows the same structure as
The president thinks sally is a senator
which second sentence, if spoken aloud, would be considered grammatical by anyone familiar with English grammar. Indeed, the “sandwich” sentence would not raise an eyebrow in certain contexts, e.g.,
The president has become psychotic and is so far around the bend that now thinks Sally, who has been his wife for thirty-six years, is a sandwich.Sally’s bite marks have needed medical treatment.
If “sally” is not intended as a proper name, the indicated sentence is not grammatical.
Of course, not everyone agrees that capitalization and punctuation are just conventions of formal writing and thus not technically part of grammar. In that case, spelling the proper name “Sally” as “sally” is a gross violation of English grammar.
Grammatical examples that, absent context, assert nonsense are bad examples because it is hard to separate content from form. Nevertheless, grammar is about form rather than content.
The A thinks that X is a P
is a grammatical form.
All this proves is the rather obvious truth that one can speak nonsense grammatically and sense non-grammatically. Grammar and sense are different realms.
When we interpret a sentence, we do so in terms of the meanings of the word in order to understand the sentence as a whole.
So why don't we parse this as "The president thought: that sally is a sandwich." In which "that" functions as a determiner for the common noun "sally". That is, with a little punctuation, a grammatically correct expression.
The reason is that there is a categorical difference between the concrete "sandwich" and the abstract "sally". A sally is sudden attack from a besieged position. It is categorically different from a bread-and-filling snack.
So it is practically and pragmatically impossible to parse "that" as a determiner.
Therefore "that" must be a conjunction, and part of the common "think that" formation
And furthermore "sally" must be a misspelling of "Sally".
The possibility of different parsing depending on the meanings of the sentence is illustrated by the pair:
Time flies like an arrow.
Fruit flies like a banana.
Apparently the same structure, but in the first "flies" is a verb and "like" is a preposition. In the second "flies" is a noun and "like" is a verb. And there is no ambiguity!
In just the same way
the president thinks that sally is a sandwich
Must be interpreted in one way: That is a conjunction, sally is a name and the capitalisation is wrong.
To add to what James K is saying, this particular sentence is ungrammatical; it should actually be:
The president thought Sally was a sandwich.
Alternatively,
The president thinks Sally is a sandwich.
Basically, the grammatical tense used should be consistent throughout the sentence.
And yes, these sentences are grammatical, even though they make no sense. Being meaningful is a quality that is separate from being grammatical; a sentence need only follow the rules of the language to be grammatical.
There’s a famous book by Oliver Sacks: “The man who believed his wife was a hat”. The author is a psychologist who has treated many extreme cases of psychosis. And yes, the man in question did indeed believe his wife was a hat. Grammatically perfectly fine.
