Probexism is the ism which states that the likelihood an observer will experience a given present is proportional to the likelihood and quantity of the pasts and futures that lead to and from it. This ism is dependent on the truth of multipathism.

Another, perhaps simpler way of stating this, excluding the observer from the definition, is as follows: if an event has many distinct likely causes and/or many distinct likely results then it is more likely to occur.

This is an explanation for increasing entropy. A regular, flat, high-entropy system has more pasts and futures than a low-entropy system.

Maybe also an explanation for gravity (see probagravism) or the other forces.