The only superstitions i believe in are spirits. Our ancestors, who were very smart people might I add, feared the unknown and I believe they did so to good reason.
Also it's important to recognize that just because something isn't explainable by science or violates some scientific laws does not mean it is non-existent.
Really believing in ghosts is a matter of personal preferences. Personally, I've had several superstitious encounters when I was young which I look back to now and realize that they weren't related to ghosts and such. However, some other encounters I have no explanations for. Also I have seen real practitioners of magic. Not the card trick magicians, real magicians. For example, a friend of mine's mother's friend went to a magician to ask the magician to make a couple divorce. All the lady told the magician was their names. For a small fee and a few disturbing rituals, the couples were divorced 2 weeks later. Coincidence? Possibly.