Double Edged Answer

It's just a simple question. Give a simple answer! Not always that easy...

Sometimes situations aren't simple. That's where the Double Edged Answer comes into play. Alice asks Bob what she expects is a simple question with a binary yes or no answer. The problem is that the answer to her question can be yes and no at the same time without either answer being factually inaccurate. Rather than just give her the simple and incomplete answer, Bob prefaces a longer explanation with some variation on "yes and no" to let her know his response has to deal with the nuances of the situation at hand.

There are multiple situations in which this trope can be played.

There was a point in time where the answer was yes, but the situation is rapidly coming to the point of being no.
Technically yes, but no.
The situation is not nearly simple enough to be explained in yes or no format.

Not to be confused with No Except Yes, or "No" Means "Yes". Compare and contrast Mathematician's Answer.

Examples of Double Edged Answer include:

Film

Flash Gordon. Emperor Ming offers to give Earth to Flash to rule.

Flash: You'd call off the attack? [snip] Everyone would be saved?
Ming: Yes, and no. After the earthquakes and tidal waves, they won't be the same human beings. They'll be more tractable. Easier for you to rule, in the name of Ming.

From Iron Man:

Soldier: Is it true that you went twelve-for-twelve with last year's Maxim cover models?
Tony Stark: That is an excellent question. Yes and no. March and I had a scheduling conflict but fortunately the Christmas cover was twins.

From both the book and film version of Harry Potter and the Philosopher's Stone about the Mirror of Erised.

Harry: It shows us what we want... whatever we want.
Dumbledore: Yes... And no. It shows us nothing more or less than the deepest and most desperate desire of our hearts.

In The Road to El Dorado, Tulio and Miguel manage to sneak off Cortez's ship with enough food to get back to Spain, with the unexpected event of Altivo jumping off the ship in chase of an apple. After saving themselves, the horse, and the boat, Altivo eats all of their food within seconds.

Tulio: Did any of the provisions make it?
Miguel: (Looks and sees Altivo eating) Well, yes and no...

Literature

In the Lucy Valentine novel "Absolutely, Positively", we have this exchange, stemming from Lucy's mother and grandmother encouraging her to move in with her boyfriend; and Lucy's fear that the family curse will break them up if they do move in together:

Sean: What?
Lucy: Nothing.
Sean: You sure it's nothing, Lucy?
Lucy: No. Yes. No.

The Lord of the Rings:

Gildor was silent for a moment. "I do not like this news," he said at last. "That Gandalf should be late does not bode well. But it is said: Do not meddle in the affairs of Wizards, for they are subtle and quick to anger. The choice is yours: to go or wait."
"And it is also said," answered Frodo: "Go not to the Elves for counsel, for they will say both no and yes."
"Is it indeed?" laughed Gildor. "Elves seldom give unguarded advice, for advice is a dangerous gift, even from the wise to the wise, and all courses may run ill...."

Live Action TV

Was one of the catch phrases in Yes Minister.

Theater

In Evita, the song "Rainbow Tour" ends with them agreeing that Evita's tour of Italy, France, and England was a success "...we had a few doubts, but the answer is yes. And no. and yes. and no."

Western Animation

Avatar: The Last Airbender: Toph tries to explain how her feet got burned: she surprised and startled Zuko in the middle of the night and he reflexively flung fire at her before he realized it was one of the Gaang. He was immediately contrite and apologetic, but Toph, in pain, bailed. She doesn't say "yes and no" precisely.

Toph: Well, he did and he didn't..

Kick Buttowski has "Kickin' Genes" in which Honey Buttowski is asked by her son if the daredevil jumpsuit he found belongs to her. She says "No. Yes! No!" before finally admitting she used to be speedboating daredevil Honey Splash, but hadn't done a stunt since an injury years ago.
Kung Fu Panda Legends of Awesomeness: "Ghost of Oogway" - Shifu stumbles into a Yes/No answer when Po asks whether Shifu wonders that Oogway would speak to someone like Po. Clearly Shifu still harbors a bit of his dubiosity about Po from the original film, despite his master's choice to name Po Dragon Warrior.
The Simpsons, "Hurricane Neddy". When Ned Flanders asks Reverend Lovejoy if God is testing him, Lovejoy answers, "Short answer, yes with an if; long answer, no with a but."
Thundercats 2011: "Into The Astral Plane", the answer to the location of the MacGuffin generates one:

Panthro: Is it in the village or not?
Tygra: It is and it isn't.

Web Comics

This strip of Schlock Mercenary.
In Sequential Art, a psychotic AI gasses all personnel in a government facility. As Art, Pip, and Scarlet are sneaking in, Pip uses a small mirror to see around a corner.

Art: Well? Any security guards?
Pip: Uh, yes and no.

In this Questionable Content page, Faye gives one because she's flustered and has issues about getting close to people.

Real Life

German Language has a word for this: "jein" (starts with "ya", rhymes with "nine"), a portmanteau of "ja" (yes) and "nein" (no).
In the same style, Swedish has "nja", portmanteau of "nej" (no) and ja (yes).
Afrikaans also has a word that can be used in this situation: Jawelnofine.
Allegedly, Columbia philosophy professor (and legendary smartass) Sidney Morgenbresser was once asked by one of his students if he agreed with Chairman Mao's proposition that a statement could be both true and false at the same time. He replied, "Well, I do and I don't."
Utilized in the following joke:

A: Will you check and see if the turn signal is working?
B: Yes. No. Yes. No. Yes. No.