Psychology's status as a science is a frequent subject of debate. A common criticism of the field holds that psychology has not been around long enough to develop a paradigm, or an established system of ideas accepted by most professionals in the community, and thus lacks one of the essential characteristics of a science. Moreover, psychology's expansive roots in other fields, including non-scientific disciplines such as philosophy, make it harder to categorize than traditional sciences such as biology or chemistry. But certain characteristics of psychology, especially its influence from established sciences and its reliance on the scientific method, are often cited as examples of why psychology should indeed be considered a science.

Roots in Established Sciences

Psychology as the scientific study of animal and human behavior is only about 125 years old, according to the American Psychology Association. But much of its core subject matter is influenced by more established sciences, particularly biology and sociology. According to the American Psychology Association, psychology combines biology's interest in the function and structure of human organisms with sociology's focus on how groups function in society. Like these fields, psychologists rely on observable phenomena to make conclusions.

The Scientific Method

A central feature of any science is its reliance on the scientific method: using observation, experimentation and analysis to support theories in a process that can be independently verified by others. Like other sciences, psychology relies on data to reach conclusions about human and animal responses to situations and stimuli. A weakness to this argument is that, unlike hard sciences that can observe measurable phenomena, much of what psychologists study is unmeasurable. A physicist, for example, can study how much moving objects stretch by measuring the length of an object while it is at rest and while it is moving, according to the textbook "Complete Psychology." Psychologists' response to this criticism, the textbook says, is that unobservable factors have observable consequences--experiments can measure human extroversion, for example, by measuring the extent to which they behave in an extroverted way.

Descriptiveness

Sciences aim to be descriptive. They try to explain theories using observation of an event or a series of events. Psychology does this through case studies, surveys, observation of people and animals in nature, interviews and psychological tests. Such research is designed to collect adequate samples of data from which psychologists can make conclusions.

Falsifiability

Sciences consider a good theory one that can be proven false through experimentation. This characteristic, called falsifiability, is a common measure of whether a discipline can be considered a science. Psychoanalysis, a field that is often confused with psychology, is considered unfalsifiable and therefore unscientific. Freud's theory that the mind consists of the ego, superego and the id, for example, cannot be tested. Scientific psychology, on the other hand, relies on theories derived through research. It attempts to create experiments that measure social phenomena against a control, mimicking the type of laboratory research conducted in more established scientific disciplines.

Objectivity

Traditional views of science state that in order to be considered a science, a discipline must be objective, a characteristic that is ensured through careful observation and experimentation. Arguments in favor of considering psychology a science maintain that psychology does this by maintaining a focus on research. Yet unlike traditional scientists, psychologists are also susceptible to personal biases that can influence an experiment. Likewise, psychology experiments are much more influenced by external factors, such as influence from participants themselves or changing social constructs over time, that make them harder to replicate than other sciences. Psychologists, like sociologists, attempt to control such influences in the way they structure their experiments, asking questions in an order designed to disguise the purpose of the study, for example.