"Is he" versus "Isn't he" as Question Tags [duplicate]

Solution 1:

As a general rule of thumb, positive clauses tend to take negative question tags, and negative clauses tend to take positive tags.

Note, however, the use of the term clauses. The negative polarity of a clause can be caused by other negative words apart from not. For example, these words with negative meanings will all give a sentence negative polarity:

• few, little, seldom, never, rarely

Because of this, clauses using these items will tend to take positive tags:

• Few people have ever actually finished it, have they?
• There's little chance of that ever happening, is there?
• Whales seldom attack humans, do they?
• You've never actually read the book, have you?
• Elephants rarely forget a face, do they?

Notice as well that negative clauses attract what are known as Negative Polarity Items. These are words (that often have positive meanings) which tend to occur in negative clauses (and often occur in questions and conditional antecedents). Here are a few of these items:

• any, ever, yet, at all

We can see from the following data that clauses with seldom pattern like clauses with not:

• *He has any time. (ungrammatical)
• He seldom has any time.
• He does not have any time.

and:

• *He has ever been on time. (ungrammatical)
• He has seldom ever been on time.
• He has not ever been on time.

also:

• *Whenever I ask him to hand the work in, he has finished it yet. (ungrammatical)
• Whenever I ask him to hand the work in, he has seldom finished it yet.
• Whenever I ask him to hand the work in, he has not finished it yet.

and lastly:

• *She goes to work at all. (ungrammatical)
• She seldom goes to work at all.
• She doesn't go to work at all.

We can see then that the reason that the original poster's example has a positive question tag, is that the main clause is negative because of the presence of the word seldom.

Solution 2:

Not necessarily. Check out this sentence:

He has never gone to England, has he?

In tag questions, the second sentence opposes the whole meaning of the first one, not just the grammar.