Are psychology and psychotherapy sciences?

In one word, YES. In my broad concept of science , there is absolutely no reason not to. They are social sciences, as they deal with people. And they differ in that psychotherapy or counselling are applied science, not basic science, with psychology playing the role of basic science.

There is also the 'discipline' of counselling psychology, which I wouldn't distinguish from the scientific side of psychotherapy and counselling.

"Not a science"

These are some arguments often fielded against the scientific status of psychotherapy and psychology:

• when studying human beings you cannot talk about science, as what you study is influenced by the studying process
• you cannot use quantitative methods in psychology
• you cannot or should not experiment with people
• everything to do with people involves meaning and interpretation, and is really hermeneutics, which isn't science
• doing science or using scientific methods objectifies your subject of study. You cannot or should not do this with people.
• some practitioners, some practices, some methods, some studies, and some articles are so deficient that they put the scientific status of the whole subjects into question
• mistakes have been made in the past, and beliefs or theories held earlier have had to be abandoned [this last one is plain ridiculous; that this has happened is far more a suggestion of scisntific status than the opposite]

To me all these objections involve mistaken or artificially and unnecessarily reduced views of what science is. Of course you can decide to make words mean what you want to, personally and idiosyncratically, but I don't see any good reason to move so far away from general usage and practice.

Applied science

Experiments and quantitative methods, whilst they definitely can be used in the psy sciences, are not necessary for science to take place. And there are enough other activities such as medicine, epidemiology, and engineering, that most definitely deserve to be qualified as (applied) sciences.

Take-away

Considering psychology and psychotherapy as scientific endeavours implies an appeal to their practitioners to set high(er) standards to themselves. This is a good thing. To be systematic, to learn from others, to share the knowledge you have acquired, to believe in knowledge and practices to be sufficiently general that we can have standards of training and of proficiency, all seem to be related to the status of psy sciences as science. And this is a 'good thing'.