For the most part I see only advantages attached to the science of psychology. In learning how the mind works, I think it helps us to better understand other people. I believe an understanding of this science helps us to better understand ourselves, as well as how we can best fit into the world in a positive way.
The human mind can be a wonderful or a terrible thing: I find it interesting to see it from all sides. It's a fascinating study, and it sometimes can shed a light of understanding with people who are seriously unwell, like Hitler, Ted Bundy, etc. It can also, however, uplift us when we learn about great minds like Stephen Hawking, Albert Einstein, Mother Teresa: people who see the world through a different lens, whether it's about intelligence or enduring sacrifice for the good of others.
The only disadvantage I can see is using psychology to excuse criminal behavior because of some kind of psychological problem or psychosis. I don't have a problem with "guilty by reason of insanity," as long as that person is institutionalized. It is not a "get out of jail free card."
I agree that some knowledge of psychology is important for several reasons, including most of those stated above. One aspect that has not been mentioned is that the great psychological theories are constantly alluded to in writing and conversation, so a lack of knowledge of these prevents one from communicating fully with others. Another aspect that I believe is important is that psychology helps us to understand great works of art and literature.
I should also say, though, that I believe that psychological theories are quite imperfect, our feeble attempt to impose various constructs on the messiness of human thought and behavior. We should all have knowledge of them, but also realize that they are constructs and not try to place people in boxes that they will inevitably pop out of.
A medical research acquaintance of mine once made the observation that "Most psychology students would be happy to understand themselves." That being said, psychology helps us not only understand ourselves better, but it enables us to have a better affinity for others. That being said, yes theory is just theory, but the study of psychology has enabled us to come to better understanding of the human psyche and what motivates it. This has helped lead to improved treatment for things such as behavior modification and habit reversal.
For teachers, a basic understanding of human psychology is essential, I think. As an undergraduate earning a degree in secondary education, I was required to take General Psych, Adolescent Psych, and Educational Psych--9 hours. I found the studies so interesting, I chose to take Abnormal Psych, which was fascinating.
Reading about human behavior is informative, but observing, studying, and interacting with it in the classroom year after year is even more instructional. I have known excellent teachers who understood the psychology of their students and interacted with them very effectively, without thinking in the language of psychology. Often they seemed to act out of very strong, intuitive interpersonal intelligence, as opposed to any formal study. The most effective methods of instruction and classroom management are grounded in sound principles of psychology, so it is important to learn and understand them, one way or another.
As an aside, developing some psychological insight can make analyzing literature even more interesting. Was Macbeth a sociopath? Was Hamlet a narcissist? Was Gatsby delusional? Were Hemingway's code heroes masters of repression? Such questions are not significant to any discussion of literature, but it can be interesting to examine literary characters in terms of what we know about human psychology and behavior.
I agree with others in that any study of psychology perhaps gives us an arrogances and helps us forget the limits of our knowledge. What we understand about the human brain and our motivation for committing certain acts is at best only partial, and theories are precisely that--just theories. Perhaps it is fortunate that science has not completely penetrated the human brain so that we become completely understandable. Long may our inner mystery be perpetuated!
I think psychology has greatly benefited the area of behavior modification. Though our study of it may yet be primitive, we have moved from a society of "sanitariums" and "asylums" to one of "rehab facilities" and "therapy programs." I really enjoy the study of psychology and behavior therapy, and sincerely believe that there are many behavioral and psychological issues that can be resolved without the use of medication.
Like others have stated, one of the disadvantages to psychological behavior therapy is that it isn't always effective and it is difficult to land on what works for each individual.
I love the whole idea of psychology to understand not only ourselves, but others. I am addicted to the criminal shows which try to solve crimes by profiling and studying the psychology of those who commit crimes either by choice or through mental illness of some kind. The brain is fascinating! However, as mentioned above, this science is subjective. Until we know more definitively, most of what we know differs from one expert to the next.
The field of Psychology is very necessary. I think the biggest concern I have is that it seems to be more subjective than the other sciences. I have worked with students that have been diagnosed with disabilities by one Psychologist and then go to another and receive a totally different one.
It seems that, in some ways, our knowledge and application of psychology is still very primitive. The movement towards insurance parity between mental and physical illnesses was, after all, very recent. But when we look back in history to how people with mental illnesses were treated in the United States in the 18th and 19th centuries, its easy to realize how far we have indeed come.
None of the advances in the understanding or treatment of mental illnesses would have been possible without psychological research.
Still, we have a long way to go, and there are mental illnesses and conditions which we still don't even understand, much less treat.
Excellent answer above. I think a major advantage of psychology is that it provides insight, possible causes, possible treatments, etc into delicate matters of the human mind.
Though it is not a medical science, it is so necessary in that the medical community definitely pays attention to and recognizes such illnesses as clinical depression, bipolar disorder, schizophrenia, Autism, ADHD, post traumatic stress disorder and so on and so forth.
Imagine if these illness, which do generally have a biological explanation, were continuously dismissed and the people who suffer were left without any treatment, including medication.
As for disadvantages, my undergrad degree is in Psychology so I think it's a wonderful discipline, but just as any other field, there needs to be a broader range of studies, more reliable studies, less bias, and more people studied (as in more minorities). But I would say that's a disadvantage for any field of Science.
I think the major advantage is that it helps us understand other people and ourselves. It gives us some insight into what makes us act the way we do.
I think the major disadvantage is that it can make us think we know more than we do. A psychological theory can sound good and that makes us think it must be true. We change our ways to conform to that theory (this happens in education a lot). But we don't always know that the theory is true because psychology can't be a hard science that can actually prove its theories.
So I think we get too confident in psychology at times and let its ideas determine how we do things even though those ideas may or may not be accurate.
Naive psychology pieces of knowledge are not precise andnot systematized, since they are not rigorously verified. Naive psychological practice is also more an art than a science. This kind of psychology has not progressed much over the centuries.
Today, given the existence of scientific psychology, there are many branches of applied psychology (medical, school etc.) that use exact procedures and methods. But still a professional psychologist can use his psychological knowledge, gained through personal experience. Naive psychology is proved to be very necessary in any psychological practice. That is why a future psychologist, or even only one future teacher should read, besides the books concerning science of psychology, novels of great writers, which are an important source of profound reflections on human behavior.