What is aggression
An aggression is a behaviour that is intended to cause humiliation, pain and harm between same species or across species. It is a behaviour by a member (one or more) of a group to with the intention of increasing their dominant position with respect to other members of the group.
Aggression can be of multiple types like physical, verbal or mental.
Difference between Aggression and Assertion
Aggression and assertion can be very easily mistaken for each other, so it is very important to understand the difference between them. Aggression basically means that I am the one who is right, and if you don't agree with me then you are wrong. There is no compromise and no common ground. Assertion means that I am right and you are also right, so we should come forward and work towards a common ground. An example of aggressive philosophy would be Lions hunting other animals of jungle, or human poaching animals in jungle to make money by doing business over their body parts.
Another example of aggressive philosophy would be foreign countries making their colonies in other poorer and harmless countries to expand their kingdom, or a teacher/principle oppressing a student who questions too much. It is quite common to see people trying to dominate and bully those who are not quite upfront and weak, not just in school and college, but also in corporate workplaces, thus making life a living hell for those who are at the receiving end. If you are working in an organization, it is quite common to see managers making their subordinates work overtime without any compensation by harassing them on job security terms.
It is easy to conclude that we find people with aggressive philosophy all around us. If you meet such people, you would know that a win-win situation is not possible with them, because they will only care about their comfort, not about others.