What is an appositive and how should it be punctuated?

Question

An appositive is a noun that immediately follows another noun in order to clarify it. An appositive usually follows the noun it explains or identifies, but it may also precede it. Restrictive appositives (essential to the sentence) are not set off with commas while nonrestrictive appositives are set off with commas.

1st Question:
How do you determine which is the appositive? Is this something that the writer decides, or is this dictated by the sentence structure?

For example, consider the following sentence in which the appositive comes before.

A bold innovator, Wassily Kandinsky is known for his colorful abstract paintings.

Then, consider the next sentence in which the appositive comes after.

Our pediatrician, André Wilson, was born in California.

Both sentences are very similar. Why does the appositive comes first in one but last in the other?

2nd Question:
If an appositive can come before the noun, how would commas be treated if we add a few words to the beginning of the sentence? Let's look at the first sentence in the previous example.

I went to the museum because a bold innovator, Wassily Kandinsky is known for his colorful abstract paintings.

If Wassily Kandinsky is the subject and "a bold innovator" is the appositive, shouldn't it be surrounded with commas? Wouldn't the correct sentence be:

I went to the museum because, a bold innovator, Wassily Kandinsky is known for his colorful abstract paintings.

But, this looks strange. What do we do?

Original Issue

By the way, I am asking this question because I had trouble figuring out the following sentence. It stumped me.

I use the upper left key, the ` key to open and close Chrome.

If the appositive is "the upper left key", then it's non-restrictive and commas are necessary. So, wouldn't you have to write it like this?

I use, the upper left key, the ` key to open and close Chrome.

But, if the appositive is "the ` key", then it's restrictive and commas are unnecessary. So, it should be written like this:

I use the upper left key the ` key to open and close Chrome.

But, it would seem that the best way to write this sentence like this, but it doesn't seem to conform to the rules of grammar.

I use the upper left key, the ` key to open and close Chrome.

In this case, the appositive is "the ` key" and it's restrictive. Yet, I put a comma after "left key".

Very confusing...

Answer 1

You have asked two questions, which isn't strictly allowed here. However, I'm going to reframe your question because I don't think all of your examples are actually examples of apposition and I think that if you understand it better you may answer your own questions.

Apposition is, as you explained, two consecutive nouns or noun phrases that identify the same subject but in different ways. They can help clarify the identity of the subject to someone who may not recognise them.

Your example of "our paediatrician, André Wilson" is a good one. You could be speaking to one person who knows your paediatrician and does not need his name to identify him. Or you could have named him first and then had to qualify his identity by adding his relationship to you, as your paediatrician. In other words, you could write this either way:

• André Wilson, our paediatrician, is a nice man.
• Our paediatrician, André Wilson, is a nice man.

Your example sentence that begins "A bold innovator, Wassily Kandinsky" is not an example of apposition. The statement "a bold innovator" certainly tells us a little about the person, but it is entirely parenthetical and does not identify him. In the previous example, you don't have to use either apposition for the sentence to make some sense and the subject to be identifiable to at least some people. But this would not make sense without the noun:

A bold innovator is known for his colorful abstract paintings.

Nobody has even identified by this statement.

To someone who has never heard of Wassily Kandinsky, the information that follows - that he is known for abstract paintings - tells us more about him yet still does not identify him. Lots of people are abstract painters and lots of people could be described as bold innovators.

If it were written as...

Wassily Kandinsky, the abstract artist known for The Blue Rider, was a bold innovator.

... then this would be apposition, as both statements identify the artist to a reasonable degree.