Theoretical Approaches: There are several theoretical approaches that have been developed by different personality theorists that focus on explaining the uniqueness of individuals. These theories have particularly been developed in the field of personality psychology that includes some popular thinkers or theorists like Sigmund Freud. Since these theories provide different approaches to understanding personality, they have been classified into different categories based on their focus and the psychologists who developed them. Some of the most common categories of personality theories include biological, behavioral, psychodynamic, trait, and humanistic and existential theories. In addition, some of the most common theoretical approaches in the personality psychology field include dispositional, learning, psychodynamic, and humanistic and existential theories or approaches.

Dispositional Theories:

The development of dispositional theories can be attributed to the work of Gordon Allport who stressed on the distinctiveness of the individual unlike any other personality theorist. Allport focused on an individual's uniqueness because of his belief that describing people based on their general traits denies them of their unique individuality (Feist & Feist, 2009, p.375). During this period, Allport refuted the trait and factor theories that seemingly lessened individual behaviors to common traits. The emphasis on an individual's uniqueness was referred to as morphogenic science, which was considerably different from nomothetic techniques used by many psychologists of theorists.

Dispositional theories are based on several assumptions including the fact that every individual has steady and long-lasting dispositions to exhibit some emotions, behaviors, and attitudes. The individual dispositions usually appear in different situations, which is the reason for people's predictable action in different settings. In addition, every individual has varying set of dispositions that contribute to a unique pattern. Generally, there are two main kinds of dispositional theories i.e. type theories and trait theories. Type theories classify people to different categories of personality based on their temperament. In contrast, trait theories are based on the assumption that people have different traits that can be regarded as ongoing characteristics that these people possess in varying amounts. These theories have contributed to development of objective personality tests that have become central to personality assessment.

Humanistic and Existential Theories:

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Humanistic and existential theories were developed based on the foundations established by Abraham Maslow and Carl Rogers (Woodward, n.d.). However, these approaches have developed to become much wider and more complex that the foundational approach established by these theorists. The main focus of these theories is valuing the basic goodness in individuals and the human potential. While the humanistic approach emphasizes basic goodness and respect for individuals, the existential approach is based on understanding and accepting a person's own existence and responsibility.
Similar to other personality theories, the humanistic and existential theories are based on several assumptions and beliefs. Some of these assumptions include the fact that an individual possesses and inherent worth by merely being human, personal growth and understanding the main goal of life, and the present is the most significant element of the individual. Based on the works of Maslow and Rogers, humanistic and existential theories embrace a holistic approach to human existence and psychological health. This is through determination of self-actualization, values, personal experience and responsibility, spirituality, meaning, and human potential.

Similarities between the Theories:

The dispositional theories and humanistic/existential theories have some similarities despite of being designed by different theorists and focusing on different aspects of an individual's personality. One of the most significant similarities between the two theoretical approaches is that they share some basic assumptions with regards to their explanation of personality. An example of the basic assumptions underlying the two theories is a more philosophical and less scientific approach. For example, Allport's theory adopts a more philosophical rather than scientific approach just like the theory of Rollo May.

The second similarity between the two theories is that they have been developed through refuting certain approached provided by other theorists and theories. The humanistic and existential theories emerged as refutation of the deterministic and mechanistic thinking or approach provided by cognitive-behavioral and psychoanalytic theories. As a result, these theories believe that people are more than machines, which implies that they deserve dignity and respect for all aspects of their being (Woodward, n.d.). Similarly, dispositional theories were developed as objection to the trait…