The function can be explained as the result or consequence of people’s action. These consequences can be either latent function or manifest function in any social institution. The distinction is explained by Robert K. Merton in his book, Social Theory and Social Structure, in 1949.
Latent functions are those functions which are unintended or unrecognized consequences of any social pattern. They are present but are not immediately obvious. On the other hand, the intended, conscious, or deliberate functions of the social policies or action which are created for the benefit of the society are called manifest functions. Manifest functions are generally expected from the institutions to be fulfilled. For example, hospitals are expected to provide better healthcare to the people or treat the patients going through any kinds of diseases, or those who met with an accident, etc. Similarly, an example of latent function can be that in a hospital the doctors while treating a patient suffering from a certain kind of incurable disease somehow saves the patient, thus, discovering a new method of treating that particular disease. This distinction between the latent function and the manifest function is the reason sociologists tend to study beyond the reasons the individuals, institutions, etc normally offer for their actions. They tend to search for the social consequences that lead to the various practices of society.
In case of manifest functions, the actor is aware of the consequences of his action while in the latent functions, the actor is not aware of his actions. For instance, if a rule is made, the manifest function will be the intended function for the fulfillment of which the rule is made. On the contrary, the unintended function is the latent function, e.g. if the rule is made in order to maintain peace, but it harms the public, that harm will be the latent function. Manifest functions are beneficial in nature, whereas, latent functions can harm as well as benefit society. Latent functions therefore have the tendency to turn into dysfunctions. However, this is not always the case. Dysfunctions are the latent functions which harm the society, create social disorder and conflict. Latent functions often go unnoticed, unless they are dysfunctions or functions resulting in negative outcomes. It is not unnatural for manifest functions to be dysfunctional at times; in many cases, it is already known that policy or action might lead to some kind of a negative consequence. But, it is the latent dysfunctions which are of greater concern because being unknown and unpredictable, they tend to bear more harm to the society which is often irreparable.
Talcott Parsons was more interested in understanding the manifest functions of social behavior, whereas according to Merton latent functions enhance the understanding about the society. Latent functions can at times support the manifest functions, e.g. a school that not only provides education but also serve the healthcare needs of poor children studying there. They might at times undermine the manifest functions. For example, the bureaucratic institution’s main task is to complement the work of the government and help it function efficiently. If its complex structure makes decision making even slower, then the latent function is viewed as undermining the manifest functions. However, in many instances, latent function might be irrelevant to the manifest functions.