Before discussing superstition we first have to distinguish between the irrational and commonsense. For example, it is commonsense not to walk under a ladder, it is irrational to fear the number 13. Putting an umbrella up in a house is considered unlucky and I suggest the likelihood of knocking something over or poking someone in the eye, makes it so. So let's just deal with the 'irrational'.
Do superstitions work? Yes they do, but only if you believe they will and even then not all the time. They work like a placebo, the power of the mind to generate positive (and negative) energy can produce very unscientific results. People who go on about a positive mental attitude do have a point. Positive things are more likely to happen when your outlook is positive. The same applies to pessimists. Project a negative energy and negative things are more likely to occur.
Being somewhat pragmatic, I am neither an optimist nor a pessimist. I know how it works ergo it doesn't, again like a placebo. If you know it's a placebo it simply won't work. This is where I sometimes have a problem with inspirational people on social media. In my mind they live in a fantasy but conversely if they can help people in a dark place, then who am I to burst the bubble. The problem is the way they tell you to avoid negative people. If you are in a fragile state I would agree but in terms of society as a whole, avoiding negativity changes nothing. It just shelters the vulnerable from harsh realities.
Back to superstition before the rambling takes me completely off course. Today is Friday 13th and the Friggatriskaidekaphobes are out in force....... or more likely still in bed hiding from the world. I joke it is the perfect day for me to buy lottery tickets which sounds a little superstitious. The way I see it, there will be so many people generating a negative energy today, thinking they have a diminished chance of winning, it leaves the door open for people like me who know superstition is crap.
So where does this most common(?) irrational superstition come from? There are a number (13? Ha ha) of proposals, some more ridiculous than others. The ones proven to be nonsense I have omitted, although it is an area of interest, 12 is a significant number in many ways so it naturally follows 13 would share some of this. When people try to rationalise the irrational, things get a little silly.
One of the most well-known hypotheses stems from Judas Iscariot and the Last Supper. Judas being the 13th at the table and the betrayer of Christ. Judas was also cited as the source of throwing salt over your left shoulder for luck. He was supposed to have knocked the salt over and Satan was over his left shoulder. It is apparently a gesture to throw salt in the eyes of the Devil. Yeah ok, we can get rid of that one.
There is an account of Hammurabi but this has been shown to be apocryphal and the only other source is from Norse mythology. Loki was apparently the 13th guest to arrive at the funeral of Baldur whose death he was accountable for. So you see there is nothing really concrete as to why 13, or Friday 13th, is particularly unlucky. In that case it is necessary to look at events that occurred on this date.
The Knights Templar were rounded up and arrested on Friday 13th October 1307 but Dan Brown had more to do with suggesting this as a catalyst. It wasn't considered unlucky at the time. Nothing much else springs to mind but the 'phobia' was in evidence and widespread from at least the 19th century. Perhaps the biggest single event that cast a shadow over 13 stemmed from the most scientific people, NASA.
Apollo 13 was launched on April 11, 1970 at 13:13:00 CST and suffered an oxygen tank explosion on April 13th. It returned to Earth four days later with no casualties but such a momentous event at a time when there was worldwide coverage, no doubt cemented certain beliefs of misfortune.
So there you have it folks, if you have Friggatriskaidekaphobia you belong to the group of silly superstitious rather than cautious superstitious.