Imagine a police lineup where ten witnesses are asked to identify a bank robber they glimpsed fleeing the crime scene.
If six of them pick out the same person, there's a good chance that's the real culprit, and if all ten make the same choice, you might think the case is rock solid, but you'd be wrong.
For most of us, this sounds pretty strange.
After all, much of our society relies on majority vote and consensus, whether it's politics, business, or entertainment.
So it's natural to think that more consensus is a good thing.
And up until a certain point, it usually is.
But sometimes, the closer you start to get to total agreement, the less reliable the result becomes.
This is called the paradox of unanimity.
The key to understanding this apparent paradox is in considering the overall level of uncertainty involved in the type of situation you're dealing with.
If we asked witnesses to identify the apple in this lineup, for example, we shouldn't be surprised by a unanimous verdict.
But in cases where we have reason to expect some natural variance, we should also expect varied distribution.
If you toss a coin one hundred times, you would expect to get heads somewhere around 50% of the time.
But if your results started to approach 100% heads, you'd suspect that something was wrong, not with your individual flips, but with the coin itself.
Of course, suspect identifications aren't as random as coin tosses, but they're not as clear cut as telling apples from bananas, either.
In fact, a 1994 study found that up to 48% of witnesses tend to pick the wrong person out of a lineup, even when many are confident in their choice.
Memory based on short glimpses can be unreliable, and we often overestimate our own accuracy.
Knowing all this, a unanimous identification starts to seem less like certain guilt, and more like a systemic error, or bias in the lineup.
And systemic errors don't just appear in matters of human judgement.
From 1993-2008, the same female DNA was found in multiple crime scenes around Europe, incriminating an elusive killer dubbed the Phantom of Heilbronn.
But the DNA evidence was so consistent precisely because it was wrong.
It turned out that the cotton swabs used to collect the DNA samples had all been accidentally contaminated by a woman working in the swab factory.
In other cases, systematic errors arise through deliberate fraud, like the presidential referendum held by Saddam Hussein in 2002, which claimed a turnout of 100% of voters with all 100% supposedly voting in favor of another seven-year term.
When you look at it this way, the paradox of unanimity isn't actually all that paradoxical.
Unanimous agreement is still theoretically ideal, especially in cases when you'd expect very low odds of variability and uncertainty, but in practice, achieving it in situations where perfect agreement is highly unlikely should tell us that there's probably some hidden factor affecting the system.
Although we may strive for harmony and consensus, in many situations, error and disagreement should be naturally expected.
And if a perfect result seems too good to be true, it probably is.
I'm Jessi, and this is my suitcase.
But before I show you what I've got inside, I'm going to make a very public confession, and that is, I'm outfit-obsessed.
I love finding, wearing, and more recently, photographing and blogging a different, colorful, crazy outfit for every single occasion.
But I don't buy anything new.
I get all my clothes secondhand from flea markets and thrift stores.
Aww, thank you.
Secondhand shopping allows me to reduce the impact my wardrobe has on the environment and on my wallet.
I get to meet all kinds of great people; my dollars usually go to a good cause; I look pretty unique; and it makes shopping like my own personal treasure hunt.
I mean, what am I going to find today?
Is it going to be my size?
Will I like the color?
Will it be under $20?
If all the answers are yes, I feel as though I've won.
I want to get back to my suitcase and tell you what I packed for this exciting week housetimothy@example.com.
I mean, what does somebody with all these outfits bring with her?
So I'm going to show you exactly what I brought.
I brought seven pairs of underpants and that's it.
Exactly one week's worth of undies is all I put in my suitcase.
I was betting that I'd be able to find everything else I could possible want to wear once I got here to Palm Springs.
And since you don't know me as the woman walking around TED in her underwear -- (Laughter) that means I found a few things.
And I'd really love to show you my week's worth of outfits right now.
Does that sound good?
(Applause) So as I do this, I'm also going to tell you a few of the life lessons that, believe it or not, I have picked up in these adventures wearing nothing new.
So let's start with Sunday.
I call this "Shiny Tiger."
You do not have to spend a lot of money to look great.
You can almost always look phenomenal for under $50.
This whole outfit, including the jacket, cost me $55, and it was the most expensive thing that I wore the entire week.
Monday: Color is powerful.
It is almost physiologically impossible to be in a bad mood when you're wearing bright red pants.
(Laughter) If you are happy, you are going to attract other happy people to you.
Tuesday: Fitting in is way overrated.
I've spent a whole lot of my life trying to be myself and at the same time fit in.
Just be who you are.
If you are surrounding yourself with the right people, they will not only get it, they will appreciate it.
Wednesday: Embrace your inner child.
Sometimes people tell me that I look like I'm playing dress-up, or that I remind them of their seven-year-old.
I like to smile and say, "Thank you."
Thursday: Confidence is key.
If you think you look good in something, you almost certainly do.
And if you don't think you look good in something, you're also probably right.
I grew up with a mom who taught me this day-in and day-out.
But it wasn't until I turned 30 that I really got what this meant.
And I'm going to break it down for you for just a second.
If you believe you're a beautiful person inside and out, there is no look that you can't pull off.
So there is no excuse for any of us here in this audience.
We should be able to rock anything we want to rock.
Thank you.
(Applause) Friday: A universal truth -- five words for you: Gold sequins go with everything.
And finally, Saturday: Developing your own unique personal style is a really great way to tell the world something about you without having to say a word.
It's been proven to me time and time again as people have walked up to me this week simply because of what I'm wearing, and we've had great conversations.
So obviously this is not all going to fit back in my tiny suitcase.
So before I go home to Brooklyn, I'm going to donate everything back.
Because the lesson I'm trying to learn myself this week is that it's okay to let go.
I don't need to get emotionally attached to these things because around the corner, there is always going to be another crazy, colorful, shiny outfit just waiting for me, if I put a little love in my heart and look.
Thank you very much.
(Applause) Thank you.
(Applause)