RE: Economic Concepts #3 - Substitutes vs. Complements

Thanks @paradigms.lost. It is important to understand the use of complements and substitutes for many reasons.

I understand what you mean by substitutability and 'zero-sumness'. For perfect substitutes it is either one or the other. In many cases the lines are a little blurred. Perfect substitutes are unusual. Most substitutes offer similarities which are sufficient to act as functional replacements.