So I'm a big fan of MBTI and have taken multiple tests. My friend and I are both psych majors but she's at berkeley and I'm not. She likes to go off on what BS the Myers Briggs is and how it's not founded in real scientific evidence. Generally this makes me feel shitty and not want to bring it up, so I was just wondering what your thoughts are?
Well, I'm not a psychologist and have never studied it in any formal sense, so please take my thoughts with a grain of salt, as usual.
I believe MBTI is a useful, if broadly misunderstood and overestimated, tool to help one understand how other people think. It is simply a crude way to categorize by personality. It isn't even close to perfect, and like all the "soft" sciences, I have a very hard time putting too much faith into any one system or theory. I mean, look at Freud- he was taken very seriously in his day, but now, he's viewed as a crackpot who projected himself on literally everyone around him. The human mind is just so nebulous, so diverse and adaptable, so impacted by culture and age and experiences, it is very difficult to think that it could be so easily generalized by something like MBTI.
I think the best way to look at MBTI (and Socionics, if that's your cup of tea) is as if it were an early taxonomic key- for me, anyway, but I was in evolutionary biology. Back in the day, all living things were sort of lumped together, with one or more "scientific names" if they were even known to natural philosophers. Eventually, a gentleman named Linnaeus came along and put together a way to organize these species so that they would be given one name, and could be organized with like species. It was Linnaeus who put together the basic system we keep today, with kingdoms, classes, orders, genera, and species.
Now, the thing is, because taxonomy was so poorly structured before this, and because Linnaeus didn't have the benefit of hundreds of years of research and advanced technology, he ended up grouping things visually. Therefore, fungi were put in the plant kingdom. All reptiles and various fish (rays, sharks, lampreys, sturgeon, anglerfish, and ratfish) were classified as amphibians. Spiders and crustaceans were named as Insects. All vaguely wormish things were grouped together in kingdom Vermes: earthworms, leeches, slugs, etc. And then there was the Mineral Kingdom, which was rightly trashed very soon after conception.
What I'm getting at is this. Linnaeus made enormous leaps and bounds in trying to organize something entirely too large and unknown for any one person to know everything about. He also made enormous mistakes. His taxonomy was massively incomplete. And yet, it organized huge collections of data into something usable and understandable... and that's more or less was MBTI does.
I think it would be dangerous to put too much stock in MBTI, especially in the long run, because that would be like continuing to argue today that anglerfish and bearded dragons are amphibians. But it has given us a way to broadly categorize personalities, the way Linnaeus broadly categorized living things. It is imperfect, yes, and there are millions of unspoken "species" within each "kingdom" of personality type. Within the "kingdom" of INTJ, two INTJs could be as similar in personality as a sponge and a peacock are in relatedness. There is incredible, generally ignored, diversity in each personality type, because like all the different species of each kingdom, we are all built by different environments and adapted for different behavior.
So, do I implicitly believe every little thing about MBTI? Not at all. Do I think it's complete garbage? No. It is not perfect or complete, but it is useful, as it makes something incomprehensible by the average person into something that can be understood. But it is very, very important not to treat it as the end all, be all, especially with so many people like me out there, untrained in psychology but talking about it to a surprisingly broad audience. It makes me very uncomfortable to assert anything about MBTI as fact or truth because of all of this, but many people don't have the same qualms, and that's how we end up with people discovering they're INTJs and ending up in my ask box feeling alone and confused because they don't fit the descriptions everybody has written about us.
I hope I've answered your question to satisfaction.