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This Goodreads discussion suggests that this is The Mind Traders, by Joan Carol Hunter Holly.
The original poster mentioned a book very similar to that described in this question:
- I read this book in 1975 or so; it featured a society in which people
with telepathic powers were ranked by how many others they could
dominate with their minds - some people were ranked as "threes" who
could only dominate 3 others, while the top of the line were "nines"
(I think). The main character was low-ranked, but learned (of course)
that he was in fact far more powerful than he thought. I was reading a
lot of Andre' Norton at the time - so this could be her. Any ideas?
Another user remembered what was apparently the same book;
- Okay, this is just weird. I thought about this very book today while I
was at work and am frustrated that I cannot recall the title. I
remember that the whole thing takes place on an alien world where
humanoids have varying powers and can control a certain number of
others to perform duties. A human investigator goes there looking for
missing humans. I hope someone recalls the title. I'm going to search
for this myself.
The second user later identifies The Mind Traders as the right title:
The Mind Traders by Joan Hunter Holly! Found it by being stubborn with
Google search.
So, I guess you can call this one "solved?", if this IS the one you were remembering.
The first user later decides that this is the book that they were looking for.
A description of this book:
A place of crawling spiders and poisonous snakes where nightmares came
true.. that was "The Black" where men were punished for challenging
minds more powerful than their own. The detective from Earth feared
The Black more than any torture his own planet could conceive. But he
had to uncover the sinister plot that threatened Earth and all its
people.
So it is certainly set on a planet other than Earth.
An Amazon review says something similar:
A human detective hunts a murderer on a planet with telepathic
natives.
I obtained a print copy of The Mind Traders, and it seems to match both the book in quote #2 and perhaps the one described in this question, but not the book described in quote #1 (i.e. the main character was not low-ranked, but rather from Earth, and thus lacks powers altogether).
Set on a planet other than Earth.
Yes. It is set on Riga:
"Missing persons. Does this ring a bell—a flurry of missing persons six months ago that ran on for a few months than stopped abruptly?"
"All right," Morgan said, "so what about them."
"They now number twenty thousand!"
Morgan let his breath out and stared at Flabert.
"Missing with no trace," Flabert continued. "Vanished completely from Earth."
"Oh." The line of talk clicked into shape in Morgan's mind. "And you think they have literally vanished from Earth. To Riga.
Our hero has no ability to control others
Yes. As an ordinary Earth human, he has no powers of mind control.
Brute strength was Earth's only possible contribution to this fight, and brute strength he had.
Locals are ranked by how many people they can control
Yes.
Morgan read the symbols, too. There was a woman with Twenty over her heart; there a man with Ten, and there an adolescent with thirty. The numbers only went by tens above the first ten. Below that they spaced by ones so there were Sixes interspersed with Fours, and even a lowly two.
However, the highest rank is Eighty, not Ten, and there are no Nulls.
There is an element of farming and people working in fields where the lowest people, the twos and ones and nulls spend much of their time.
Yes. As mentioned previously, there don't seem to be "nulls," and the scale is a bit different from what you described, but the low-ranked people work in the fields:
"Rather than keep you worrying, I'll get right to my point. As a Ten, you do a great deal of farm work, don't you?"
She nodded, and Jael said nothing.