I know that most close-up card magic involves the classic “force” - that is, getting your mark to select the card you want him to select.
What if your mark doesn’t fall for it? Are you screwed?
You don’t have to be screwed, just have a back up trick to switch to, and a bad joke to segue from the abandoned gag to the next.
Patter is everything. If you shovel enough poo poo you can do a whole set with only two repeating gags.
One of my favorite routines that a friend used to perform involved demonstrating a bunch of forces before the trick began. He’d go, “pick a card, didja get the four of diamonds?” I know because I forced you to pick it like this. Then he’d show how the force worked, then do the same thing again with another force, several times, making them pick the four of diamonds.
Then, now that he’d educated the victim on various card forces, he’d spread the cards on a table facedown and tell them to pick any card, with the magician not touching anything. (What the victim didn’t realize is he had just switched the deck for one with all four-of-diamonds! Ha!)
Fascinating. From the OP title, I thought it would be about the Jedi Force and the Jedi Mind Trick. 
I may have seen a stage magician do this. Well, unless he was planning all along to just do that joke right then? Which is, I guess, pretty much the whole point.
Anyway, he does the “pick a card” bit, and the audience card-picker isn’t playful or enthusiastic; if anything, he’s got an Oh-I’m-Gonna-Spot-Your-Trick face on. And the magician, all patter and flourishes, soon holds up a card and scrutinizes it like mad while the stony-faced guy (a) can of course only see the back of it, and (b) is asked, after he’s been picturing it, what his card was. “Six of hearts,” he says.
“Six of hearts? Six of hearts! Now, tell me if you see – The Six Of Hearts!”
It’s a trick card, with fifty-two little ‘card’ images on it.
Penn & Teller’s force card for years was 3 of clubs. They would go out of their way to show “unique” methods of revealing the denouement. Once–ick–it was on Teller’s eyeballs (fancy rubber cornea coatings).
A few things:
I wouldn’t say “most” card tricks use a force. It’s certainly a powerful tool, but so is careful card control without a force. And, of course, good presentation for any trick is what matters most.
There are also a lot of different techniques for forcing a card, and most of them are foolproof. The “classic force” is certainly strong in that it gives a clear impression of a free choice by the spectator, but other forces that aren’t subject to chance can be just as strong, especially when they make sense in the context of the trick. (Some are a bit hammy or unnatural, but you don’t have to use those!)
When using a classic force, yes, one needs an alternative path for the trick in case it doesn’t go to plan. In an extended set, you just keep the intended trick on hold while you do some other prestidigitation in the meantime.
<Waves hand> “This is the card you’re looking for.”
“This is not the card I’m looking for.”
“No, I said this is the card you’re looking for.”
“This is not the card I’m looking for.”
I remember some years back, there was a thread on this board asking “How does the pick-a-card-any-card trick work?”. Amusing, to think that someone thought that was only one trick.
I saw a variant of this at The Magic Castle in Los Angeles, once:
Magician* pulled some random gorgeous girl out of the front row and ran through the usual who are you, what do you do, patter. She had a heavy accent but said she was a student at UCLA. The magician handed her a huge book, told her to open to any page and he would recite the first line at the top. She flipped the book open, paged forward a bit, and said, “Okay.” The magician turned his back, raised a hand dramatically and said, “What light in yonder window breaks?”
Then he turned around and the young lady shook her head and read aloud, “I bear a charmed life, which must not yield to one of woman born.”
“What?!” he asked, “Are you sure you’ve read that right?”
“Yes.” she nodded, “I told you I’m a student. I’m an English Major specializing in Shakespeare – in fact this is the same book as my textbook. This passage is my favorite; I chose my major because I love Shakespeare’s MacBeth.”
By this time, we in the audience were either holding our breaths while waiting to see how the performer would resolve the unplanned mess, or openly snickering because we knew he had been outgunned.
“Oh! Well…good for you!” he clapped and smiled graciously, “Thank you so very much for participating tonight!” and he took the book from her and she returned to her seat. The audience cheered and applauded – I suspect more for her than for the magician in that instance. Then the magician simply moved on to his next trick. What else could he do?
–G!
*A year earlier I had seen the same guy perform the same trick successfully with a different random (yet gorgeous) girl from the front row.
Was it “what light in yonder window breaks” a year earlier?
Yes. It’s What light in yonder window breaks? every time.
The engineering is that the book is subtly mangled to make it fall open to the right page and the magician starts the trick with something like “Think of your favorite Shakespeare play and open the book to a random page.” Romeo and Juliet is the most popular of Shakespeare’s works, even non-fans know that particular play, and “What light…” is one of the most recognizable lines. The average mark would be likely to give at least noncommittal agreement that it’s his/her favorite of The Bard’s works. It might even be the only piece of Shakespeare he/she knows.
But, a year earlier, the magician spent more time chatting with the audience member, partly to crack jokes and partly to prep the trick, “Do you like to read?” and “Do you know who Shakespeare was?” During the trick that failed, he was having trouble understanding her (she had a pretty thick Ukranian accent) and had her repeating her personal info a couple times. I think he cut the prep questions to regain time. I think he should have at least asked what she was studying at UCLA.
—G!