CompassionI believe that all humans are born with an inherent compassion, for both animals and other people, which is usually partly removed through conditioning by human culture.
Compassion and Violence
Most humans have difficulty with performing violence on other humans or creatures; most people are quite gentle.
For most humans to be able to perform violence on another living being,
they must objectify that being to become a thing; they must separate
themselves from the being and place themselves above him or her to
be able to treat the being as an object.
In the same way, animals are not referred to as pig or cow; they are referred to as pork or beef. When an animal's flesh is named the same as an animal, such as turkey or chicken, people resort to making jokes about the animal to resolve their uncomfortableness about eating the animal, as is evident around most Thanksgiving day dinner tables.
It is not at all a surprise that animals are treated without concern for their pain when used in animal research, when one considers how they are treated when killed and eaten for food.
Sometimes, people say they don't hate other races, but simply insist that the other race is different in some way. This difference places one race above the other, allowing people to exploit and use them. For example, blacks in South Africa are commonly thought of as stupid and as thieves, so that there is no hesitation by the whites to exploit them as domestic servants, and to do other injustices.
Circle of Compassion
Everyone has a "circle of compassion." One cares deeply about everyone within this circle. Some people limit their circle just to their immediate family; some include the family animals. The animals living with a family tend to be called "pets" to separate them from other types of human-controlled animals, for which there is less compassion.
Some people do not have any compassion, but some people manage to care about almost everyone, even the insects they might breathe in or step on.
Everything outside of the circle is not emotionally important to the individual. Someone might care about their own pets and the pets in the shelter, but would not care about the animals used in research. Someone might care about the animals killed for meat, and be vegetarian, but not care about the cows killed in the process of milk production. Someone might care about everything but the soil animals crushed as one walks across the grass or killed as pests in organic agriculture.
There are reasons for these definitions of the circles; they vary from person to person. One is cognitive dissonance; another is ignorance of what can actually feel pain; another is basic selfishness. A main reason is pure despair; you may feel you cannot possibly worry about every living animal and avoid harming them. Avoiding harm to life as much as possible is worth it, because you will know you've done your best.
The best example of this: trapping spiders and carrying them outside to be set free, instead of killing them.