I've got a question regarding Peterson's fascination with Jung for those who are more familiar with that particular subject, but why is it that people like Peterson are drawn to Jungian thinking, and why was it discarded in modern Psychology? I know it's been relegated more towards being useful in terms of literary tools and what not, but what exactly about it isn't applicable in the field itself? Is it because it's hard to prove?
I've had something akin to more than a passing interest in Psychology itself, and Jungian thinking was one of those things that really puzzled me and I've always wanted to know more about it.
A lot of that was due to trends in the English speaking world that impacted the structure of higher education. Like every other discipline, Psychology isn't monolithic and is fragmented into various branches and sub-fields that are often independent of each other and geographic considerations are also important: the study of psychology in central Europe can look very different from the study of Psychology in China.
In the context of the United States/Canada/Britain/Australia, in the mid-20th century there was a shift towards a kind of "positivism" in the soft/social sciences that placed a heavy emphasis on research being easily quantifiable through some kind of metric that can be tracked. Grand theories of human behavior that are more akin to a literary theory or philosophical hermeneutic don't lend themselves to that kind of research and because one's ability to obtain grant money was and is still critical for funding one's research, pitching your ideas framed in a way that appears "data driven" becomes of paramount importance. Other fields like Political Science, Economics, and Sociology were similarly affected.
To make matters worse, for those who got into psychology for clinical work soon found themselves contending with insurance companies and government agencies who were very picky about how and when they are going to reimburse practitioners for their services. So therapies that can be superficially quantified for a billing statement become preferred. Case in point, Cognitive Behavioral Therapy becomes the go to therapeutic strategy because you can structure a 10 session block around patients/clients completing worksheets and journal entries that can easily be translated into a chart to measure "progress" that can then be billed discretely.
In the end you discover that a lot of psychologists end up having a strong affinity towards a particular thinker like Freud, Jung, Adler, or God help us Jacques Lacan which then informs projects that are geared towards metrics. Peterson had a thing for Jung that greatly informed him on a meta-level, but he earned his tenure through his work on assessing personality.