If a scientist were faced with such a question he or she would begin taking accurate measurements of the water in the glass. If these measurements determined that the water line was exactly in the middle of the glass and the volume of water was exactly half of what the glass could hold, the scientist would say that both answers were technically correct and were communicating the same thing.
But we all know that the two reactions to the same glass of water (half full or half empty) could not be further apart and dissimilar, regardless of the physical measurements.
This is why science stays away from values and subjectivity. Science is baffled by the phenomena of subjective, person-level experience (human consciousness).
Scientifically speaking, the glass of water should be experienced the exact same way by all observers. Science cannot take into account a deeper, psycho-spiritual reality of people having different states of minds and outlooks. So science is left in the rearview mirror when it comes to the things which are most important and intimate to our selfhood. To take the scientific position concerning this glass of water would make the human psyche lifeless.
However, all true religion addresses this innermost realm of the human spirit. We need a new religion that offers the deepest answers for proper living for the entire human race (consciousness is lame without conscience).
This new religious/spiritual movement has already begun to spread throughout the planet Earth!