Abstract
Qualitative psychology and cultural psychology are new beginnings for the discipline of psychology. These new
beginnings also require a new methodology to fit the open systemic nature of phenomena. The trajectory equifinality
model (TEM) is a new methodology for depicting the diversity of the course of human life. The concept of
equifinality originated in the general system model of von Bertalanffy, and it means that the same final state may be
reached from different initial conditions and in different ways. It is a general property of open systems. In the
minimal case, the dynamics of the open systems entail the notion of individual trajectories that may diverge (at
bifurcation points) or converge (at equifinality points). Therefore, the TEM maps the individual histories of particular
systems onto the wider general system of possible trajectories that arrive at the equifinality point. After reviewing the
historical and philosophical background of the TEM, important concepts such as the equifinality point (EFP),
trajectory, bifurcation point, irreversible time, polarized EFP, and obligatory passage point (OPP) are explained.
Then, three studies applying this methodology are presented so that new researchers can understand and practice this
new methodology. Finally, the implications and limitations of the TEM are discussed. It is noted that all
psychological research necessarily needs to analyze processes of psychological kind (rather than time-free essences
that psychologists posit to "exist", like "intelligence", "personality" etc.), and TEM is a first step towards providing a
workable alternative to existing statistical orthodoxy.
