Reciprocity (social and political philosophy) in the context of "Lex talionis"

Credit (from Latin verb credit, meaning "one believes") is the trust which allows one party to provide money or resources to another party wherein the second party does not reimburse the first party immediately (thereby generating a debt), but promises either to repay or return those resources (or other materials of equal value) at a later date. The resources provided by the first party can be either property, fulfillment of promises, or performances. In other words, credit is a method of making reciprocity formal, legally enforceable, and extensible to a large group of unrelated people.

The resources provided may be financial (e.g. granting a loan), or they may consist of goods or services (e.g. consumer credit). Credit encompasses any form of deferred payment. Credit is extended by a creditor, also known as a lender, to a debtor, also known as a borrower.

Social justice is justice in relation to the distribution of wealth, opportunities, and privileges within a society where individuals' rights are recognized and protected. In Western and Asian cultures, the concept of social justice has often referred to the process of ensuring that individuals fulfill their societal roles and receive their due from society. In the current movements for social justice, the emphasis has been on the breaking of barriers for social mobility, the creation of safety nets, and economic justice. Social justice assigns rights and duties in the institutions of society, which enables people to receive the basic benefits and burdens of cooperation. The relevant institutions often include taxation, social insurance, public health, public school, public services, labor law and regulation of markets, to ensure distribution of wealth, and equal opportunity.

Modernist interpretations that relate justice to a reciprocal relationship to society are mediated by differences in cultural traditions, some of which emphasize the individual responsibility toward society and others the equilibrium between access to power and its responsible use. Hence, social justice is invoked today while reinterpreting historical figures such as Bartolomé de las Casas, in philosophical debates about differences among human beings, in efforts for gender, ethnic, and social equality, for advocating justice for migrants, prisoners, the environment, and the physically and developmentally disabled.

The norm of reciprocity requires that people repay in kind what others have done for them. It can be understood as the expectation that people will respond to each other by returning benefits for benefits, and with either indifference or hostility to harms. The social norm of reciprocity may take different forms in different areas of social life, or in different societies. This is distinct from related ideas such as gratitude, the Golden Rule, or mutual goodwill. See reciprocity (social and political philosophy) for an analysis of the concepts involved.

The norm of reciprocity mirrors the concept of reciprocal altruism in evolutionary biology. However, evolutionary theory and therefore sociobiology was not well-received by mainstream psychologists. This led to reciprocal altruism being studied instead under a new social-psychological concept: the norm of reciprocity. Reciprocal altruism has been applied to various species, including humans, while mainstream psychologists use the norm of reciprocity only to explain humans.