There is something called the third eye or the eye of intuition. We can perceive truth and scientific matters through these means as well. It's how saints are able to tell the future and explain things they have never done research on.
However if you are looking for physical evidence. If one...
Fossils indicate the growth and evolution of consciousness from primal and instinctual animals to more intelligent and civilized beings that live now. It indicates that we are heading towards higher and more spiritual ages.
I'm glad you admitted to that. Spiritual and self experimentation through meditation techniques is a form of scientific experimentation. Especially kundalini meditation if done properly.
I'm just saying regular modern day scientists will never know what Saints know if they don't experiment...
Of course there is always going to be a few bad apples or a few immoral men on a good side of a war. It is an individual thing but there are some wars that are fought for righteous reasons. Such as defending the world from Nazi's and Al Quaida.
Science is not a good source when it comes to spiritual matters or discussions. Reason being is science is thousands of years behind what true saints have discovered.
According to my beliefs all beings have an afterlife. Humans are more precious than animals in the karmic law because of their spiritual chakras and thousand petaled lotus in the brain. These are what allow for God Realization meanwhile animals cannot.
I did answer the question! Example Al Quaida knows they are wrong when they are killing POWs on a camera. Sure there may be some that are so brain washed they don't know what is right anymore but I'm sure for the most part they do know that what they are doing is wrong.
The less humane people...
There is a meaning to life, it is to help yourself and others to become more spiritual. At the same time to enjoy the infinitude of God's outward manifestations. If you leave the earth more spiritual then when you entered and have helped others to be more happy and closer to God then you have...
Look into your heart. You can tell if it's righteous or not. If it is not derived from selfish motives or out of injustice then it is righteous. If it is for a better future and protects people's freedom of life and or helps others to live peacefully then it is righteous.