> If you're trying to say psychology is not an exact science I agree.
It's not a science at all. Sciences make observations, then craft generalizing theories to explain the observations, then test the theories in unrelated contexts, then discard those theories that fail. This is certainly not how psychology works. In psychology, it's commonplace to see a therapy for a disease whose existence hasn't yet been established, or that was brought into being by a secret vote rather than a microscope (as was true during the DSM-5 editorial process).
Am I exaggerating the requirements for real science? Let's perform a thought experiment to see. Let's say we can have science without theories, only with observations, as in modern psychology. Here goes ...
Let's say I'm a doctor and I've created a revolutionary cure for the common cold. My cure is to shake a dried gourd over the cold sufferer until he gets better. The cure might take a week, but it always works. My method is repeatable and perfectly reliable, and I've published my cure in a refereed scientific journal (there are now any number of phony refereed scientific journals). And, because (in this thought experiment) science can get along without defining theories, I'm under no obligation to try to explain my cure, or consider alternative explanations for my breakthrough — I only have to describe it, just like a psychologist.
Because I've cured the common cold, and because I've met all the requirements that psychology recognizes for science, I deserve a Nobel Prize. Yes or no?
Ask yourself what's wrong with this picture, and notice that the same thing is wrong with psychology — all description, no explanation, no established principles on which different psychologists agree, no effort to build consensus, and no unifying theories.
> You can't use psychology to make exact predictions of how people will behave however the more you learn about psychology the better you get at figuring out people and make a educated guess what motivates them.
Only if you're suffering from a bad case of confirmation bias. You need to understand that psychology is undergoing a major upheaval eight now, mostly because of improvements in neuroscience that suggest neuroscience will eventually replace psychology, in the same way that astronomy replaced astrology in the 17th century.