If it is Psychology you want to discuss, then I think rather than start with ethics it would make sense to say what Psychology is. Here is a start:

https://www.bbc.co.uk/science/humanbody/mind/articles/psychology/what_is_psychology.shtml

So is the basic premise here that psychology is not an empirical science? Because if it is, it seems to me that this is just the problem of induction.

Of course generalisations are not impossible. But they may have different degrees of validity, which depend on context, including context of purpose.

Anyway, it's a frustratingly vague OP. Please say more about what you're trying to get at specifically.

So is the basic premise here that psychology is not an empirical science? Because if it is, it seems to me that this is just the problem of induction. — Echarmion

That's pretty much the issue here. I don't think anything I said amounts to much more @Baden.

Of course generalisations are not impossible. But they may have different degrees of validity, which depend on context, including context of purpose. — Baden

I don't even know how to address this. What allows one to determine that the same methodology of psychology can be determined one or more individuals?

@Wallows

Psychology is a social science, but the same basic principles of deduction and induction apply as do to science in general:

"... inductive and deductive reasoning go hand in hand in theory and model building. Induction occurs when we observe a fact and ask, “Why is this happening?” In answering this question, we advance one or more tentative explanations (hypotheses). We then use deduction to narrow down the tentative explanations to the most plausible explanation based on logic and reasonable premises (based on our understanding of the phenomenon under study). Researchers must be able to move back and forth between inductive and deductive reasoning if they are to post extensions or modifications to a given model or theory, or built better ones, which are the essence of scientific research."

Principles of Social Science Research

You tend to find a significantly higher amount of qualitative vs. quantitative methodology though than in the hard sciences.

https://www.simplypsychology.org/qualitative-quantitative.html

Can a psychologist generalize findings towards a larger group of people and achieve a normative stance?

If generalizations are impossible due to the intrinsic relativism of individuals, then what can be said about the field of psychology as a whole? — Wallows

A psychologist can do as he likes. It's up to the rest of us to winnow out the chaff.

But I'd say, in the main, an observational science. Of course one can ask "why" of observed phenomenon. But psychology has an atrocious track record in making appropriately neutral observations and interpreting them.

Why "in the main"? Because there are psychologists who do science.

It's akin to history. The science of history primarily lies in methods of uncovering what (actually) happened, as closely as possible. Historian's get into trouble when they theorize about history, or try to give an account of history.

And it's not so much about any intrinsic relativism; rather it's about the difficulty in merely accurately recording what happened, and then arguing back from that as consequence, to causes.

(..)all matters of human psychology essentially boil down to ethics. — Wallows

Why is this so?

Can a psychologist generalize findings towards a larger group of people and achieve a normative stance? — Wallows

It is probably best to treat each case individually.

I think mental states do present a problem in terms objectifying them and evaluating them. But mental health might be assessed base on how a person feels or functions. There is nothing preventing large groups of people having similar mental states I would imagine.

I think this OP boils down to something personal.

What is the real issue, Wallows ?

No matter what Wittgenstein says on the matter, not all human psychology boils down to ethics.
How does having psychotic symptoms or schizophrenia boil down to ethics.
If I have misunderstood the point being made, I look forward to clarification.

From the link I provided earlier which describes all the various branches of psychology, where clinical psychology is the first of ten :

Clinical psychologists, unlike psychiatrists, do not have a medical background, and for this reason they do not diagnose illnesses or prescribe medication. Instead, they try to understand people's difficulties in the context of their background, life events and the sense that they have made of their experiences.

On this basis, they work with clients and teams to develop psychological formulations for people in distress. A formulation is a concise summary of why a person has developed their difficulties, and draws on psychological theory and evidence. For example, a formulation may show that a client's low mood may be a response to having a critical or dominating parent, or to a period of unresolved grief following a major bereavement.

The formulation provides an agreed starting point for the psychologist and the client...

That's what general statistical psychology does it provides those who know it with a normative set of values, values concerning groups of people. The psychologist is prone to 1) biases from statistics as well as 2) biases from his own sense of regularity and commonality among his patients. The effective psychologist will make due note of his own normative stances and stand back from than when viewing individual patients, attempting to have a non-bias knowledge of who they think they are talking to. However, it may be helpful at times to categorize or generalize patients. Knowing when to and when not to is a learned skill.