I'm curious as to our resident expert's thoughts on the Meyer's Briggs personality type categorizations... is there really any substance to them? The whole thing smacks of pseudoscience to me.
The Meyer's Briggs is not accepted as valid within Psychology itself. Its harshest critics are Psychologists.
Its invalidity doesn't reflect on Psychology as pseudo-science any more than Nurses advocating the efficacy of prayer (happens alot) reflects on biology as a pseudo-science. Meyers-Briggs is basically pop-psych made popular in the corporate world by charlatan "consultants" profiting off of the corporations with lots of $ to blow and lots of motivation to get any competitive edge they can.
A great deal of what happens in hospitals is pseudo-science, but that is also a reflection of why profit motive corrupts any and all science, not an indictment of biology.
Its important to keep in mind that "Psychology" is a broad category that includes basic lab research about human cognition and behavior to clinical practice where an individual is treated for a specific diagnosis, to a group of people who have no particular problems just being given advice to improve themselves in some vague way. The training for these careers have as little in common with each other as does the training to be a genetic scientist versus a pediatrician or a certified gym trainer.
Most psychological researchers are not supportive of much of what is done under the banner of clinical practice. And most clinical practitioners are critical of pop-psych, corporate consultants, etc.. That said, it is legit to hold the APA accountable for its near total failure to enforce any standards of practice by the people that it grants a licence to. Basically, they just need to get through the training hoops, and the get it, and it rarely revoked no matter how unscientific their clinical methods are. Part of the issue is that bad therapy rarely kills your clients or harms them in any provable way. So, malpractice suits are rare, unlike in medicine.
That said, the Meyers-Briggs is not as completely random and baseless as astrology and horoscopes. The planets positions when your are born have zero possible impact on the type of person you are. In contrast, the type of person that your are does have some impact on how you answer various questions about what is most important to you, your preferences, your basic worldview, how you act in various situations, etc..
For example, one Meyers Briggs question is: Do you trust reason rather than feelings? It not a perfect question and its vague, but ask me that everyday and I will always say "Yes". Ask some other people and they will say "No". Odds are high that people's answers to that predict their religiosity, whether they believe in all sorts of paranormal notions, and whether they accept the consensus scientific view on many issues from evolution to vaccines. Some of the questions really suck, but some probably do reflect meaningful and stable differences between people. The real problem arises when they take a bunch of questions like that on totally different things that happen to be correlated, and then try to extract some specific underlying personality dimension as the underlying cause of all the responses. Imagine a car that has quick acceleration, handles corners well, and is compact, and has sleek lines to it. Those are all important qualities. We might slap a label on it of "sporty", but the car has no property of "sporty" and "sportiness" doesn't actually explain its actions related to those qualities. That's a decent analogy for how to think of personality "types".