Are there different ways to tune an instrument?
How did the note A get it's pitch determined?
Who determined what pitches are used?
How would you tune a Guitar, or Ukelele?
In the middle of the 18th century the practice of temperament changed dramatically. There was a traditional way composers tuned for centuries that didn't allow for them to use all the keys equally. The effort to change how instruments were tuned led to our modern style today. To achieve this, instruments were actually detuned slightly. We are all very used to this out of tune sound and it doesn't bother us now. It infuriated traditional composers then.
Is everything relative? Is truth relative? Who says what the right tuning is?