5 This fact is sometimes described as a lack of commutativity on the part of the addition function. But the mathematical construct of addition cannot have the property of commutativity in some contexts and lack it in others. Addition is defined to be commutative. But when the addition construct is interpreted as describing growth, (5 + 3) and (3 + 5) refer to two different growth processes. The difference between the two cases resides in the real world, not in the mathematical construct.