First, to most psychologists, a need is as a psychological feature that arouses an organism to action toward a goal and the reason for the action, giving purpose and direction to behavior.
The most widely known academic model of needs was proposed by psychologist Abraham Maslow. In his theory, he proposed that people have a hierarchy of psychological needs, which range from security to self-actualization. However, while this model is intuitively appealing, it has been difficult to operationalize it experimentally. It was further developed by Clayton Alderfer.
One of the problems with a psychological theory of needs is that conceptions of "need" may vary radically between different cultures or different parts of the same society. One person's view of need may easily be seen as paternalistic by another.
The second view of need is represented by the work by political economy professor Ian Gough. He has published on the subject of human needs in the context of social assistance provided by the welfare state With medical ethics professor Len Doyal , he also published The Theory of Human Need.
Their view goes beyond the emphasis on psychology: it might be said that an individual's needs are representative of the costs of being human within society. A person who does not have his or her sexual needs fulfilled -- i.e., a "needy" person -- will function poorly in society.
In the view of Gough and Doyal, each person has an objective interest in avoiding serious harm that prevents the endeavor to attain his or her vision of what's good, no matter what that is exactly. This attempt requires the ability to participate in the societal setting in which an individual lives. More specifically, each of needs to have both physical health and personal autonomy. The latter refers to the capacity to make informed choices about what should be done and how to implement that. This requires mental health, cognitive skills, and chances to participate in society's activities and collective decision-making.
How are such needs satisfied? Doyal and Gough point to eleven broad categories of "intermediate needs" that define how the need for physical health and personal autonomy are fulfilled:
How are the details of needs satisfaction determined? The authors point to rational identification of needs using the most up-to-date scientific knowledge; the use of the actual experience of individuals in their everyday lives; and democratic decision-making. The satisfaction of human needs cannot be imposed "from above."
This theory should be compared to the capability approach developed by Amartya Sen and Martha Nussbaum. Those with more internal "assets" (education, sanity, physical strength, etc.) have more capabilities and are more able to escape or avoid poverty. Those with more capabilities fulfill more of their needs.
In his 1844 Paris Manuscripts, Karl Marx famously defined human beings as "creatures of need" or "needy creatures" who experienced suffering in the process of learning and working to meet their needs These needs were both physical needs as well as moral, emotional and intellectual needs. According to Marx, human development is characterised by the fact that in the process of meeting their needs, humans develop new needs, implying that at least to some extent they make and remake their own nature. This idea is discussed in more detail by the Hungarian philosopher Ágnes Heller in A Theory of Need in Marx (London: Allison and Busby, 1976). Political economy professor Michael Lebowitz has developed the Marxian interpretation of needs further in two editions of his book Beyond Capital.
Professor György Márkus systematized Marx's ideas about needs as follows: human beings are different from animals because their vital activity, work, is mediated to the satisfaction of needs (an animal who manufactures tools to produce other tools or his/her satisfactors), which makes human being a universal natural being capable to turn the whole nature into the subject of his/her needs and his/her activity, and develops his/her needs and abilities (essential human forces) and develops himself/herself (a historical-universal being). Work generates the breach of the animal subject (needs)-object fusion, thus generating the possibility of human conscience and self-conscience, which tend to universality (the universal conscious being). Human being's conditions as a social being are given by work (but not only by work) (it is not possible to live a human being without a relationship to others): work is social because human beings work for each other with means and abilities produced by prior generations (a universal social being). Human beings are also free entities able to accomplish, during their lifetime, the objective possibilities generated by social evolution, on the basis of their conscious decision. Freedom should be understood both in a negative (freedom to decide and to establish relationships) and a positive sense (dominion over natural forces and development of human creativity, of the essential human forces. To sum up, the essential interrelated traits of human beings are: a) work is their vital activity; b) human beings are conscious beings; c) human beings are social beings; d) human beings tend to universality, which manifests in the three previous traits and make human beings natural-historical-universal, social-universal and universal conscious entities, and e) human beings are free.
In his texts about what he calls "moral economics," professor Julio Boltvinik Kalinka asserts that the ideas exposed by David Wiggins about needs are correct but insufficient: needs are of a normative nature but they are also factual. These "gross ethical concepts" (as stated by Hilary Putnam) should also include an evaluation: Ross Fitzgerald's critics to Maslow's ideas reject the concept of objective human needs and use instead the concept of preferences. They assume, just like many other logical positivists, that values cannot be rational and assert, therefore, that the definition of poverty threshold, a task charged with values, is an arbitrary action of researchers, an assumption which implies a narrow view of poverty.
Marshall Rosenberg's model of Compassionate Communication, also known as Nonviolent Communication (NVC) makes the distinction between universal human needs (what sustains and motivates human life) and specific strategies used to meet these needs. In contrast to Maslow, Rosenberg's model does not place needs in a hierarchy. In this model, feelings are seen as indicators of when human needs are met or unmet. One of the intended outcomes of Rosenberg's model is to support humans in developing an awareness of what life-sustaining needs are arising within them and others moment by moment so that they may more effectively and compassionately find strategies to meet their own needs as well as contribute to meeting the needs of others.
People also talk about the needs of a community or organization. Such needs might include demand for a particular type of business, for a certain government program or entity, or for individuals with particular skills. This is an example of metonymy in language and presents with the logical problem of reification.