Let's switch topics for a while.
But the discipline is very poorly defined and it allows unscrupulous individuals (such as practising psychologists) to say almost anything about anybody, and as long as it is plausible not many people will question it. — RepThatMerch22
Well, unscrupulous individuals do lots of bad things in every field, from warehouse management to the priesthood. Why would psychology be any different?
But let's pass over that, just right now.
As a discipline, psychology grew out of philosophy. A lot of philosophical concerns issues we now classify as psychological. An example of this are discussions about consciousness, and whether one can experience having experiences. What about dreams? Will? emotions? All this stuff is fair game in philosophy. Do you think philosophers handle it so much better?
There are several sub-fields in psychology that philosophy didn't develop:
Abnormal Psychology. ...
Biological Psychology. ...
Child Psychology. ...
Clinical Psychology. ...
Cognitive Psychology. ...
Comparative Psychology. ...
Community Psychology. ...
Counseling Psychology...
I trained in counseling psychology at the masters level, so I have a small vested interest in psychology as a field--that was 45 years ago. Was it a creditable program? Some of it was, some of it wasn't. The program trained high school counselors. One of the first readings in the program was about the various people in a high school from whom a troubled student would seek out help. Counselors were last on the list, janitors were first. I should have taken a cue from that and moved on, but I didn't.
The best classes in the program dealt with personality theory and group psychology (IMHO). True enough, there are widely discordant theories of personalities, but there are themes that are common to all of them, like the importance of childhood experiences and learning. We know more about the genetic influences on personality, intelligence, and behavior now than we did in 1971. We know much more about brains structure, thanks to PET scans, MRIs, fMRIs, CT scans, portable EEGs, and so on.
Despite the individual uniqueness people display, people are really quite similar. Not that everyone is alike, but rather, people are consistently similar in the kinds of things they do, and the kinds of thoughts they have. That is why we can understand each other. We are members of the same species, and like other species, we tend to behave similarly among ourselves.
There are a lot of things we don't know about human behavior, like... how do people develop sexual fetishes? Why do some people experience alienation, anomie, and isolation, while their peers (similar backgrounds, similar experiences, similar influences) do not? What are the short, medium, and long term effects of technology like smartphones, Facebook, or twitter?
Tell us more about your objections to psychology as a field.