A superstition is a belief that is not based on logic or reason. Superstitions often promise to protect someone from harm or in some way affect the future. For example, opening an umbrella in a house is said to lead to bad luck, finding a four leaf clover would bring good luck, and wearing a special gemstone or crystal would ward off evil. These superstitions have no logical basis, yet they are still followed by millions.
People believe in superstitions because they want to believe in them. It's easy enough for believers to find coincidental connections and label them as proof, or to simply say that their superstitious beliefs defy explanation. Interestingly, a belief in superstitions can actually appear to affect a person's "luck," though what it really affects is a person's outlook.
The human mind is powerful, and events that are based on a person's performance can be influenced by that person's outlook or beliefs. This is commonly known as a placebo effect.
When a superstitious person breaks a mirror (which is supposed to bring seven years of bad luck) he may actually perform poorly on a test, forget his lines during a play, or miss an easy layup during a basketball game. Conversely, carrying a rabbit's foot may give the same person the confidence to do well in all of those areas (if he actually has the necessary skills).
This is why superstitions are so prevalent among athletes, actors, and students. Some athletes may decide that they have to perform a certain ritual, like turning in three circles before leaving the locker room or wearing a certain pair of lucky socks. Thespians often do not wish each other good luck before a play, as that is supposed to have the opposite effect. Instead, they tell each other to "break a leg," and they never say the name of the Scottish Play unless they are on stage performing it.
Superstitions have arisen in nearly every culture, yet some superstitions have opposite meanings in different countries. In the United States, both black cats and the number 13 are unlucky. Yet black cats are lucky in Britain and the number 13 is lucky in Italy. Does a black cat's luck change when it makes a trip across the pond? And what happens if a black cat crosses in front of both a Brit and American who are walking on the same street?
Though superstitions have some interesting background stories and can have a placebo affect on those who believe in them, they all seem to come back to a matter of control. People want to have control over the events in their lives. They will believe in many strange ideas to gain even an illusory sense of control. Yet, if control is so important, why do some people seem to prefer superstitious beliefs over scientific fact?
At the most basic level, some people associate the term "belief" with positive concepts like emotional sensitivity, artistry, inspiration, magic or faith, but attach negative connotations to "facts," such as being dry, boring or unimaginative. Beliefs are uplifting; facts are grounding. That alone can be enough to make some people shy from staid facts and embrace more magical beliefs.
Superstitious beliefs may also be seen as more accessible than scientific facts. To be confirmed, scientific facts must be objective, verified observations. They must stand up to investigation with consistent results. Superstitions, on the other hand, defy logic and simply require belief. People can "just know" they are "true," instead of being bothered with proving them to others.
Superstitious people often say, "I don't know how it works, it just does." And, when it comes to performance, maybe superstitions do work--in a way. A basketball player might score more points when wearing his lucky socks, but give those same socks to a kid off the street who doesn't have the baller's skills or dedicated training regime, and he'd still be riding the bench.