Why are weaknesses strengths and strengths weaknesses?

Answer 1

What constitutes a strength or a weakness is subject to criteria (i.e.) you have to hold some standard to determine it). Nothing is purely free, so every action has some sort of cost, or consequence. When people assess a 'strength', there is inevitably some cost to it (so, subject to the criteria, the benefit is the 'strength' and the cost is the 'weakness'). Since people primarily do actions to benefit themselves, everything has a strength and a weakness. By depending on a certain strength, you are exposed to the cost and risk of using it. By being weak, you are not dependent on the source of strength and thus its costs.