Every [[options|option]] has some [[Probability of success|chances to succeed]]. Every option is constructed from a cascade of events, and every event has some probability to happen. It may depend on the known probabilities of an event to happen (for instance we may assume that our chances of winning the lottery have a probability of 1 to a million), or the level of corroboration (the number of times we tested the theory). The more we corroborated the theory we may have more confidence we can predict her chance to occur (from an epistemological perspective we do not have any way to predict the future, bet let’s leave this for now). Consequently, when an option has many steps (events that should occur in order for her to succeed), or/and when the events are not well tested, the probability of success falldrops.