Aggression in human society is a highly complex phenomenon and covers a wide range of behaviour. It should be distinguished from aggressiveness. Aggressive behaviour can be considered to have a positive aspect in that it affords the natural drive to gain mastery over the external world, thus underlying the necessary attainment of individual independence and most of the greatest human achievements. It ordinarily fits the pattern of normal adjustment, while aggression tends towards maladjustment and abnormality, with behaviour that is essentially destruction oriented.

In a psychological sense, aggression refers to any manifestation of a self-assertive disposition. There is still considerable dispute as to whether it is simply a response to adverse external circumstances. It is nevertheless becoming increasingly apparent that particular styles of aggression relate to particular social contexts and roles and are thus culturally patterned.

In a political sense, aggression refers to any manifestation of an expansive policy; in a military sense to an unprovoked military attack; and in a legal sense to the use of armed force by a government in violation of an obligation under international law or treaty. In the last sense, the term has appeared in numerous treaties and official declarations since World War I, including the League of Nations Covenant and the United Nations Charter. In 1933, the signatories of the Convention for the Definition of Aggression agreed to define the aggressor in an international conflict as that state which is the first to commit any of the following actions: (a) declaration of war upon another state; (b) invasion by its armed forces, with or without a declaration of war, of the territory of another state; (c) attack by its land, naval, or air forces, with or without a declaration of war, on the territory, vessels, or aircraft of another state; (d) naval blockade of coasts or ports of another state; (e) provision of support to armed bands formed on its territory which have invaded the territory of another state, or refusal, notwithstanding the request of the invaded state, to take on its own territory all the measures in its power to deprive those bands of all assistance or protection. Furthermore, it was stipulated that no political, military, economic, or other considerations could serve as an excuse or justification for such acts of aggression.

There is still no answer to many scientific questions and there exists an uncertain degree of knowledge with regard to major disciplines. The physical and behavioural sciences such as psychology and economics, which are so frequently looked to for certitude, do not always come up with clear cut answers; and unsubstantiated theories often disguise a lack of knowledge.

While one category of ignorance applies to what is not known, another category applies to the inability to assemble all the facts needed. For example, although there may be considerable understanding of the effects of single policies on single objectives, where multiple and sometimes conflicting effects and objectives of programmes and policies exist the processes for evaluating all these may be too complex, so that decisions are made in ignorance of all the relevant data.

Another type of ignorance allows for the knowledge to exist and also the capability and means to acquire it, but the will to do so is not present. Unwillingness to look at the facts constitutes intellectual bias. An emotional bias has the same effect, such as identification with a particular set of interests whether they are national, political, economic, ideological or religious. In the latter case, a tenet of Roman Catholic theology, for example, describes those who will never embrace Christianity due to their heredity, upbringing or environment, as 'invincibly ignorant', which aptly describes the 'closed' mind in any situation.

Central areas, especially in the major cities of the west, are those parts of urban settlements where the concentration of the entire range of economic, financial, political and cultural activities is the greatest and the most complex. Traditionally they have been the scenes of co-existing housing, artisanal industries, business and many other economic and socio-cultural functions, in which they acted as clearing-houses for the exchange of goods, ideas and knowledge. This co-existence is now threatened. Although industries which in the past caused disruption and damage to the environment are gradually moving out, living and working in central areas can still be a traumatic experience. This is particularly true of the city centres in many industrialized countries, which exhibit environmental degradation. The numerous and highly competitive activities entailing land use overwhelm the limited space and create a situation of overcrowding, functional incompatibility and cultural degradation. Inner city areas have a high level of commercial specialization, a large number of offices and a sizeable daytime population. At the same time, city centres generally remain a sort of ghetto for a permanent, low-income population living in run-down housing and enjoying little in the way of public services and civic amenities. The concentration of the service industries inevitably entails the replacement of traditional housing and shops by office blocks, the provision of basic utilities at the expense of civic amenities and the provision of major access roads which eat up urban space. The ensuing over-concentration of traffic has the inevitable consequences of air pollution, visual obstruction by masses of vehicles and a disproportionate consumption of central spaces for transport needs. Structures of historic origin are often unable to meet modern requirements and, notwithstanding their value, frequently face demolition. Some of the future-oriented activities hitherto dominating central areas tend to abandon the stifled centre and look for more favourable locations. It also uproots the rightful inhabitants , who, finding themselves jobless in the city centres, gradually move to the outskirts and thus hasten the decay of the inner city areas while greatly increasing the demand for utilities in the new locations.

The social disparities existing in central urban areas have a cumulative effect; underemployment and unemployment increase the inequalities and mean that the already under-privileged fall still further behind. Inter-related negative factors begin to operate and they often lead to alienation and violence with, as a consequence, the exodus of those who can afford to leave and their replacement by new arrivals fascinated by the big city. Decaying buildings with no settled occupants become haunts of crime, drug use, violence and fear. As businesses, good schools, and educated people leave, city centre's have the poor, uneducated, undesirable minorities and sick. Housing deteriorates. Schools become less capable of educating as violence increases, funds decrease and the best staff leave. Teachers see themselves as baby sitters or policemen. Social services deteriorate; medical services become more centralized into public hospitals and private practices move to better neighbourhoods; unemployment and welfare agencies become part of the means of oppression; and police services shift emphasis from prevention to restricting crime to defined geographical areas. Private housing becomes substandard as returns on investment drop below zero. Arson for the sake of insurance claims is the most profitable way of recovering investments from property. Residents see no need to maintain rental property as any improvement will not be paid for by the owner and is likely to attract criminals. Public housing is often the location of high rates of crime: women are raped in elevators and drugs pushed in hallways. Access to the political processes becomes more difficult until indifference sets in for the voting population and corruption and cynicism become mechanisms for survival for politicians. The private sector invests less and less. Jobs move further and further away. Transportation is by old junk cars for those who can afford them, luxury automobiles for the criminal and increasingly bad public services for the poor. Shopping for necessities means either paying higher prices for lower quality goods or travelling to distant and frequently alien centres. Criminal investments increase with gambling, prostitution and drugs. The self image of residents and employers becomes either one of a victim of circumstance or one of an outlaw. The absence of controls governing land use is unfortunate in the city centres of many market-economy countries where, in most cases, the incremental value of land flowing from community growth is not made available to the community to finance its further development, but is largely accrued to land speculators.