As Doc John and others have mentioned, medicine is a combination of science and art. Doing medicine does NOT equate to doing science, but relying on science, much as engineers do. Doctor is a high professional technician of the body as engineer is of grand humanmade structures. Since these applied sciences are part not they are not wholly sciences, ie I don't consider them sciences, though they rely on some scientific techniques. They rarely if ever focus on the fundamental nature and relationships of things, and thus are not essentially science. And psychiatry is a branch of medicine, so all this applies to psychiatry in spades. Considering it would be difficult to objectively define any fundamental natures of the human mind, it only makes sense it's not essentially a science.