> "There are many assumptions in the article and in your comment. "

I'm confused. As I read the post, it contains the bits "The most important step comes next, where you try to find out what ketamine is actually doing, since, again, there's no happiness dial in the brain. ... This step is crucial, because it allows you to find out which effect of ketamine is providing the benefit, because there are many."

While the possibility you take as 'assumed' is the jumping off point for the hypothesis, it is explicitly a testable hypothesis for which the necessary test to (in)validate the original assumption is explicitly defined.

So what exactly is the problem?