What is it to be disabled? Where does the term "disability" come from?
People are a mixture of thrownness (Heidegger’s description of the state in which we exist), self-determination and circumstances sometimes outside of our control. Within this mix, no person alone can be described as being disabled; they are just being themselves. The term “disabled” arises only when people are compared to each other (including your past self compared to your present self).
Physical and mental disability is considered a lack of ability only because another person happens to have that ability. We live in a wonderfully complex world full of individuals with unique skills and abilities. If disability arises from an act of comparing, then everyone is potentially disabled depending on whom they are compared to. For example, the athlete Usain Bolt is disabled compared to the swimmer Michael Phelps because he physically can’t swim as well as Phelps (and Phelps is disabled when compared to Bolt).
Whether it is Parkinson’s disease, an inability to run 100 metres in under 10 seconds or millions of other reasons, everyone can be considered disabled. Therefore, the division between able and disabled people, which the word “disability” signifies, is a false division. Disability is always a relative term. For example, we all have the "disability" of only seeing light in the visual spectrum but since we can't be compared to someone who can see more of the spectrum its not considered a disability.