The Thomas Theorem

Perception & Consequence

The Thomas Theorem

Photo by Brendan Church on Unsplash

The Thomas Theorem states that, “If a person perceives a situation as real, it is real in its consequences.” This thinking dictates that behavior is dependent on the subjective interpretation of reality rather than objective reality. More importantly, behavior is shaped in a manner that creates consequences and results based on the subjective belief. There are many examples of this Theorem, but perhaps one of the glaring examples of this theorem can be seen in the concept self-efficacy. Self-efficacy is defined as the perception of an individual’s ability to resist or change a particular behavior. Self-efficacy refers to a person’s belief in their own competence to perform in a certain manner and/or attain certain sets of goals. Often self-efficacy is applicable to any event or circumstance that requires an act of will power. Whether a person is determined to get straight A’s in school or to quit smoking, a level of belief in one’s own ability to achieve these goals is necessary for the attempt to be made. If a person does not believe he or she can get straight A’s, then they might not see the point in even trying. Self-efficacy is a determining factor for how people feel, think, motivate themselves and behave. In this way, it certainly affects a person’s goals because it affects the person’s behavior and ability to motivates the person to reach those goals. If a person believes that he or she can make it through the necessary effort or challenge to successfully achieve their goal, they are more likely to do so. Self-efficacy has a cause and effect relationship to which is rooted in the Thomas Theorem. It should be noted that self-efficacy is impacted by more than just belief. Self-efficacy is also intrinsically linked to self-perception, self-esteem, and self-concept.

If you are happy with yourself, odds are high that you will be happy with your life. And compared to those with a poor self-image, people with a positive self-view are likely to enjoy more initiative, more persistence in the face of obstacles, more effective stress coping, and more positive social relationships (Baumgardner & Crothers, 2009).

One of the strongest examples of this can be seen in the ability of people to quit smoking. Despite the fact that nicotine is a highly addictive substance, individuals are able to quit smoking with greater success when they believe that they can quit smoking. In studies of smokers, the research clearly shows that self-efficacy increases the success of individuals quitting smoking as much as 30–40% (Carey and Carey, 1993).

Self-efficacy is an example of the Thomas Theorem in action because individuals who believe that they can quit smoking are able to do so because they shape their behavior to conform with this belief. For example, when a person believes that he or she can quit smoking then they are more likely to act in ways that conform with the belief such as avoiding activities that may increase the desire to quit smoking such as drinking (Carey and Carey, 1993).

This self-efficacy ties in with social construction of reality because individual behaviors are also impacted by a person’s backgrounds and beliefs. Within the context of quitting smoking this can be seen as a factor that increases or diminishes the perception of the a situation. This can be understood in an example of a person who was raised to believe that determination is a key factor in achieving a goal. If a person is taught from an early age that having determination is the necessary component of achievement, then this person will be more likely to achieve their goal.

Social construction impacts the behavior of a person, because if the person was raised to believe that he or she has little control over any given situation, then he or she will be less likely to achieve their goal. Within this framework, the Thomas Theorem impacts the manner in which people behave based on belief, but this is impacted further by social construction. This is sometimes referred to as self-fulfilling prophecies which is rooted in both the Thomas Theorem and in social construction of reality.

Self-fulfilling prophecies occur when a person believes that a particular outcome will come true and then it does due to their own behaviors. This problem occurs due to the combination of the Thomas Theorem and the social construction of reality. This can be seen in situations such as discrimination in which some groups are oppressed due to beliefs that are not founded in reality. According to Schaefer (2012), a self-fulfilling prophecy can occur when individuals believe a person or group has a specific characteristic; then, the individual begins to exhibit that description that they are perceived to possess. For example, self-fulfilling prophecies surface when majority group members perceives subordinate group members as lacking skills needed for advancement to higher skilled positions that keep the subordinate group in lower paying jobs (Schaefer, 2012).

The Thomas Theorem and social construction of reality are both forces that can create positive and negative outcomes for individuals. While these concepts are important, the actual impact of these ideas are debatable. There are definitely impacts related to these ideas but the extent to which these concepts impact behavior is debatable. The idea that believing in an idea can make it a reality has merit, but this also practical and realistic limits to this concept. Simply, believing that you will become rich does not guarantee this outcome. However, it may increase your odds.


Baumgardner, S. R., & Crothers, M. K. (2009). Positive psychology. Upper Saddle River, NJ: Prentice Hall.

Carey, K., & Carey, M. (1993). Changes in self-efficacy resulting from unaided attempts to quit smoking. Psychology of Addictive Behaviors, 7(4), 219–224.

Schaefer, R. (2012). Racial and ethnic groups (13th ed.). Upper Saddle River, NJ: Pearson Prentice Hall.


Vincent Triola. Mon, Feb 08, 2021. The Thomas Theorem Retrieved from