The oppisite of a superstition, a substition is the belief in something that is utterly true. Coined by Terry Pratchett in 'Making Money'.
When my mother told me not to pick at my scab or it wouldn't heal, I saw immediately that she was very substicious (believing greatly in a substition).
If being superstitious is believing in things that aren't true, being substitious is believing in things that are true, but that very few people believe to be true.
There are many substitions, which include "It'll get better if you don't pick at it," "Sometimes things just happen," and "There are a lot of things in the world that you don't know about."
Terry Pratchett describes 71-Hour Ahmed as substitious, which "places him in a minority amongst humans."
— Taken from the page everything2.com/title/substition, explaining substition according to Terry Pratchett, who originated the term in the Discworld novel Jingo.