Often, I find arguments where people are assumed to be rational

Bias

Often the desirable outcome of an action or 'strategy' is taken to have been the goal that the actor deliberately attempted to attain.

Diamond in a box:

Suppose you're faced with a choice between two boxes, A and B. One and only one of the boxes contains a diamond. You guess that the box which contains the diamond is box A. It turns out that the diamond is in box B. Your decision will be to take box A. I now apply the term volition to describe the sense in which you may be said to want box B, even though your guess leads you to pick box A.

Let's say that Fred wants a diamond, and Fred asks me to give him box A. I know that Fred wants a diamond, and I know that the diamond is in box B, and I want to be helpful. I could advise Fred to ask for box B instead; open up the boxes and let Fred look inside; hand box B to Fred; destroy box A with a flamethrower; quietly take the diamond out of box B and put it into box A; or let Fred make his own mistakes, to teach Fred care in choosing future boxes.

But I do not simply say: "Well, Fred chose box A, and he got box A, so I fail to see why there is a problem." There are several ways of stating my perceived problem:

Fred was disappointed on opening box A, and would have been happier on opening box B.

It is possible to predict that if Fred chooses box A, Fred will look back and wish he had chosen box B instead; while if Fred chooses box B, Fred will be satisfied with his choice.

Fred wanted "the box containing the diamond", not "box A", and chose box A only because he guessed that box A contained the diamond.

If Fred had known the correct answer to the question of simple fact, "Which box contains the diamond?", Fred would have chosen box B.

Hence my intuitive sense that giving Fred box A, as he literally requested, is not actually helping Fred.

If you find a genie bottle that gives you three wishes, it's probably a good idea to seal the genie bottle in a locked safety box under your bed, unless the genie pays attention to your volition, not just your decision.

--CEV

it appears to me that human beings are emotional, situationally defined social animals, much more than they are rational actors

You imply that there is a standard of rationality people are deviating from. Yes?