Definitions (like axioms) are not right or wrong. They are just choices. For a group of people speak the same language, they must use similar meanings for similar words. But natural language is not like mathematics. Meanings vary from person to person, and even from discussion to discussion.
When someone gives a definition they are not invalidating someone else's definition, or invalidating their opinion - they are simply defining the use of a word or phrase with the current discussion or context.
Anyone who is arguing over the 'correctness' of a definition is stupid - as it is a pointless exercise. Some definitions may be overly complicated. Some may be contrary to common use. Some may be not very useful. But they not wrong - they just are.
To clarify ones thoughts, it is sometimes helpful to to apply Occam's Razor to definitions, and use the simplest definition which is appropriate. Sometimes this includes things which are counter-intuitive. Sometimes this gives insights we would not otherwise have gained.
In arguments, many people play the redefinition game (definition hijacking) - choosing to quietly redefine terms in the middle of an argument, to help support their own conclusions.
People also choose to play the sloppy-quantification game. For instance someone might claim that 14.3 percent of people suffer mild depression, but when pressed, admit that there is no actual definition of mild depression. In this case their figure is irrelevant.
The definitions used in this work are not the only definitions which could be used. Others works may use different definitions, and may arrive at different conclusions, and neither might be wrong. The definitions in this work are the simplest definitions which seem to fit examples which most people agree on. Some of the definitions may seem cynical, but only for phrases where no objective definitions are available, and which have been used emotionally in arguments to try to draw an objective conclusion.