How we change what others think, feel, believe and do
Authority vs Expertize
Imagine you are a lawyer in a courtroom. You bring in a witness on tobacco ash and have a choice between two introductory statements:
'Mr Holmes is an expert on tobacco ash'
'Mr Holmes is an authority on tobacco ash'
Both statements mean the same thing, that Mr Holmes knows all about tobacco ash. Which one should you use? Does it make any difference?
Expertize is mastery over a subject. It implies achieving a high level of skill or knowledge such that others may consider us expert. In other words our level of knowledge and/or skill in some subject is high.
Calling someone an expert hence means their statements in their area of expertize are likely to be true. We hence believe experts because they know more than us and we assume they know pretty much everything in their area of expertise. Asserting expertize says 'I know better than you, so believe what I say'.
Authority is a vested position of superiority. A person in authority has been given that authority, usually by an even higher authority. Managers, for example, have authority. However this authority is not universal. Their authority is over their subjects. The nature of authority is that the person can issue commands and their subordinates must do as they are told. If they do not, they may well be punished.
However, there is another meaning of 'authority', as indicated in the 'Holmes' example above. As well as 'having authority' (or being 'in authority') we can make it a noun, saying a person is 'an authority'. This effectively means a person is an expert, with sufficient knowledge to be able to pronounce on various matters.
Sometimes people have both expertize and authority, such as when doctors prescribe a cure. Sometimes, however, expertize and authority do not correlate. It is not uncommon for those in authority to assume expertize. They pronounce on various topics, even though they are not experts. People agree with them and accept what they say, not because they accept the person in authority as an expert, but because the person has the ability to punish any disagreement. This can lead to significant problems where a manager disagrees with experts who are also subordinates.
When a word can have multiple meanings, the sense in which we use each variant is defined by its context. Sometimes this is clear from the syntax of the statements, such as when we say 'in authority' or 'an authority' to differentiate the meaning of the words. Sometimes the meaning is based more on surrounding sentences or even the physical situation, for example in court, it is clear that the witness is not a formal superior to anyone there.
Unconsciously, when a word has multiple meanings, we have to consider all possible meaning in order to select the one that best suits the situation. When we have selected the best meaning, the other meanings still hang around and may subtly influence our thoughts. This can happen with 'expert' and 'authority'. Returning to our 'Holmes' example, declaring him an expert effectively says 'He is likely to be right', while using the word 'authority' brings in the implication that he must not be challenged. The lawyer may hence choose the appropriate word depending on whether the intention is to challenge Holmes' expertize (use 'expert') or to for the jury to never question Holmes' statements (use 'authority').
The bottom line: craft your persuasive speech with an understanding of how alternative meanings of words still have an influence on how people think, decide and behave.