One of the main arguing points against Psychology being classed as a science is that it does not have a unified approach. For example, Biology has the common descent theory as it's unified standard. All Biological theories revolve around this theory, that all life has evolved from it's predecessors. It is argued that Psychology does not have a theory like this, therefore it cannot be a science. However, perhaps the field has something else to unify the approaches?
Early Psychologists attempted to unify different theories and fields using structuralism. Structuralism was revolutionary as it was the first method of thought to seperate Psychology from Biology, and religions. It attempted to seperate the mind from the body, and seperated the mind into different components, and 'brain processes using subjective measures (Titcher, 1910). Structuralism used a method called introspection to obtain an insight into the human mind. However, the theory was criticised by many, as the data was subjective and obtained by an unreliable method (introspection was a mainly self-report scheme of research). Because of this, the findings could not be reliably applied to other people (e.g an entire population), and could not be applied to real world issues. For this reason, this unifying theory was considered unscientific.
From the criticism of structuralism came the unifying theory of functionalism. This theory, which forms the basis of modern Psychology, attempted to connect the mind to the body and analyse mind functioning by analysing how the mind works. It uses mental operations instead of elements of the mind, focusing on the purpose of behaviours, and uses emprical, objective evidence to peform assessments of the mind. This theory led to developments of different approaches to Psychology, for example the Biological and Humanistic approaches. Researchers realised that the field of Psychology was too broad to be contained under one unbrella term, and branched out. However, whilst the different fields sometimes conflict and offer vastly different approaches, they all use the same theory of functionalism; using emprical evidence and being objective with the research and their findings. Because of this, it could be argued that Psychology has a unified theory, and is therefore scientific.
