Superstitious belief, by definition, have no scientific basis.
Science requires that ideas are tested in a way that is
repeatable and falsifiable. Falsifiable means that
there must be a way that the test shows that a stated belief is
not true, while most superstitions rely on metaphysical
entities or powers that are so vague they can not be
Here are some examples of superstitions, and where they may have
Breaking a mirror is seen as seven years of bad luck from a
Back in the medieval times mirrors were very expensive. And if
you broke one, it was reguarly someone important, such as the lord
of the kingdom of the king or a high-ranking nobleman. And if you
broke it, it was common that if they were un-forgiving, they would
put you in jail, possibly for seven years.
Walking under a ladder is seen as bad luck
Typically a ladder means someone at the top of the ladder and
that person can easily drop things - onto your head. So it really
is a bad idea to walk under one.
Never sweep the floor at night or you'll sweep sorrow into your
You may not be able to see where you're sweeping and fall and
Chase away any owls outside your window; they are a harbinger
They may erode your windowsill by pecking on it, and when you
lean on it, it may break and you may fall.
Never start or buy anything on a Friday.
Since Friday is the last business day, you or your order will
probably not be active on the weekend.
Cut your hair on a full moon and it will grow back faster.
Well, if you cut your hair at a barber's shop, and you can see
the moon, the barber will probably bee in a hurry to leave and so
will give you a shorter haircut.
Crickets in your home are good luck (not in my home and
definitely not for the nasty crickets!)
They tell the temperature.
Killing a spider is bad luck.
In addition to reducing local disease-carrying insects, spiders
provide humans with other medical benefits. Spider venom is used in
neurological research and may prevent permanent brain damage in
stroke victims. The silk produced by spiders is used in many
optical devices including laboratory instruments.
Ivy growing on a house protects the inhabitants from witchcraft
Evil may mistake it for poison ivy and stay away.
Friday the 13th is unlucky
The Templars were all arrested (and most were tortured and
executed) one Friday the 13th!
Actors believe that using real money as a prop is bad luck.
This is probably rooted in the fact that leaving real money on
stage or in your costume means that there is a good chance that the
prop will disappear before the next performance.
Opening an umbrella in the house is bad luck.
Like walking under a ladder, this is just a hazard; you could
hit someone or break something.
Bad luck comes in threes.
This is sometimes expressed in notable deaths occurring in
threes. In fact, this is a well-known psychological bias known as
"confirmation effect"; when two events occur, people naturally
anticipate a third (two things don't form a pattern, but three do).
When the expectation is satisfied, it "proves" the adage. Of
course, if it is not, then the pattern is not recognized.