An old joke, expanded unreasonably!
An optimist says a glass is half full, and thus decides to enjoy the provided bounty by drinking the rest of it.
A pessimist says the glass is half empty, and drinks the rest before it disappears too.
The engineer says the glass is double the necessary capacity, and drinks the water whilst pondering whether it would be easier to get a smaller glass or to resize the current one appropriately.
The scientist remarks that it would have taken (x) hours for the water, assuming the glass started full, to evaporate to such a level, given the current humidity and temperature. At this stage, the scientist then is sufficiently thirsty that they drink the water.
A programmer looks at the glass, ponders it for a while, drinks the water and then refills the glass to see if it happens again.
A cynic, meanwhile, demands to know who drank half their water, launches an investigation, and is thus the only one to survive after all that arsenic got dumped in the water supply.