An obligation is a requirement to take some course of action, whether legal or moral. There are also obligations in other normative contexts, such as obligations of etiquette, social obligations, and possibly
in terms of politics, where obligations are requirements which must be fulfilled. These are generally legal obligations, which can incur a penalty for unfulfilment, although certain people are obliged to carry out certain actions for other reasons as well, whether as a tradition or for social reasons. Obligations vary from person to person: for example, a person holding a political office will generally have far more obligations than an average adult citizen, who themselves will have more obligations than a child. Obligations are generally granted in return for an increase in an individual’s rights or power.
Common obligations of citizens include a requirement to participate as a juror if called upon and to pay taxes, which is seen as being in return for the right to participate in the electoral process and receive financial and physical protection from the state. Another example, though not a common law obligation, is the US Constitutional requirement to participate in a census every ten years, which, like many legal obligations, often incurs a fine if not fulfilled.
The term obligate can also be used in a biological context, in reference to species which must occupy a certain niche or behave in a certain way in order to survive. In biology, the opposite of obligate is facultative
, meaning that a species is able to behave in a certain way and may do so under certain circumstances, but that it can also survive without having to behave this way. For example, species of salamanders in the family Proteidae
are obligate paedomorphs
, whereas species belonging to the Ambystomatidae
are facultative paedomorphs