Science:

– Why X?
– Interesting question? Why do you think X?
– No clue…
– Let’s figure it out… how about if we added Y?
– I added Y once, it didn’t go so well.
– Let’s add Y anyway and see if that is a pattern.
– Your funeral… but sure, let’s wear protective gowns and keep a safe distance and I’m game…

Religion:

– Why X?
– Because God said so!

Celsius:

“The scale is based on 0°C for the freezing point of water and 100°C for the boiling point of water at 1 atm pressure.” /Wikipedia

Fahrenheit:

“The lower defining point, 0°F, was established as the temperature of a solution of brine made from equal parts of ice and salt. Further limits were established as the melting point of ice (32°F) and his best estimate of the average human body temperature (96°F, about 2.6°F less than the modern value due to a later redefinition of the scale). The scale is now usually defined by two fixed points: the temperature at which water freezes into ice is defined as 32°F, and the boiling point of water is defined to be 212°F, a 180°F separation, as defined at sea level and standard atmospheric pressure.” /Wikipedia