Reclaiming Psychological Type: A Systemic Functional Model Bridging MBTI and Trait Theory

The influential 1989 reinterpretation of the Myers-Briggs Type Indicator (MBTI) by Costa and McCrae reframed the instrument within the Five-Factor Model (FFM), advancing the claim that MBTI preferences are best understood as linear traits corresponding to four FFM dimensions. This trait-based account has shaped the dominant scientific consensus for decades, largely displacing the MBTI’s roots in Jung’s model of psychological functions. This paper offers a critical re-evaluation of that reinterpretation, demonstrating through subsequent empirical data—especially Furnham et al. (2003)—that key predictions of the 1989 model, including the “Unity hypothesis,” are not supported. Methodological oversights, such as the neglect of multivariate typological interactions, further weaken the trait-only account.In response, the paper introduces the Systemic Functional (SF) Model—a polarity-based framework grounded in Jungian theory and modern typological scholarship. It interprets MBTI preferences not as isolated traits, but as indicators of an underlying systemic configuration of interacting psychological functions arranged in a coherent hierarchy. Drawing on published correlational data, the paper shows that the SF Model predicts a distinct, theoretically ordered pattern of FFM Conscientiousness across all 16 types, offering a more nuanced and empirically supported account than the simpler FFM reinterpretation.The SF Model directly addresses the criteria proposed by Costa and McCrae for typological validity—demonstrating qualitative differences, functional hierarchy, and systemic interaction effects. It thereby challenges the assumption that trait-based models are inherently superior, instead proposing a theoretically grounded, falsifiable, and integrative approach. By bridging trait theory (FFM), type indicators (MBTI), and dynamic functional structure (Jungian psychology), the SF Model invites a broader scientific dialogue and lays the foundation for renewed empirical engagement with the inner structure of the psyche.