For the sake of making (we hope) a somewhat humorous illustration of the matter at hand, we offer the following scenario, which shows how tutor and tutee can talk their way to a workable thesis - and, indeed, to a good essay. So sit back, and enjoy this "break" in your training.
Imagine (though it is indeed quite a stretch) that a freshman composition teacher has the audacity to assign a paper on cats (the animals, not the play). The students may write any kind of paper they like - narration, description, compare/contrast, etc. - as long as their essays contain a thesis (that is, that they argue some point) concerning cats. A writer comes to you for help in developing her thesis. You read the assignment, and then you tell the writer that she first must choose the kind of paper she would like to do. She decides to do a narrative because she thinks she has more freedom in the narrative form. Then you ask her what she has to say about cats. "I don't like them," is her reply.
"OK," you say, "that's a start. Why don't you like them?" The writer has lots of reasons: they smell, they're aloof, they shed, they keep you up nights when they're in heat, they're very middle class, they steal food off of the table, they don't get along with dogs (the writer loves dogs), and on, and on. After brainstorming for a while, you tell the writer to choose a few points on which she'd like to focus - preferably those points that she feels strongly about or those which seem unusual. She picks three: cats smell, they steal food, and they are middle class. She offers her thesis: "I don't like cats because they are smelly, thieving, and middle class."
"O.K.," you say, "It's not a very sophisticated thesis but we can use it for now. After all, it defines your stance, it controls your subject, it organizes your argument, and it predicts your strategy - all the things that a thesis ought to do. Now let's consider how to develop the thesis, point by point."
You begin to ask questions about cats and their smell. "What do they smell like?" you say. The writer thinks awhile, and then says, "They smell like dirty gym shorts, like old hamburgers, like my eighth-grade math teacher's breath." The writer laughs, particularly fond of the final simile. Then she adds, "My boyfriend has a cat. A Tom. When he moved into his first apartment, that cat sprayed all over the place, you know, marking his territory. The place stunk so bad that I couldn't even go there for a week. Can you imagine? Your boyfriend gets his first apartment, and you can't even go in the place for a week?"
The writer has sparked your imagination; you think that she can spark her teacher's imagination as well. "Why don't you do your narrative about your boyfriend's cat? You could tell the story - or you could make up a story - about going over there for dinner, hoping for a romantic evening, and being put off by the cat." The writer likes this idea and goes off to write her draft. She returns with the following story about her boyfriend and his cat.
She was hoping for a romantic dinner; he was making her favorite meal. She could smell the T-bone and the apple pie before she even got to his door. But when she opened the door, her appetite was obliterated: the smell of cat spray smelled worse than her eighth-grade math teacher's breath. Of course, because she remained hopeful for a romantic evening, she put on her best face, tried not to grimace, and gave her boyfriend the flowers she'd picked up on the way. They chat; everything is going fine; he goes to the kitchen to check on dinner; she hears his shriek. The cat has stolen all of the food! Upon searching, they find the cat under the sofa, not only with their dinner, but with the writer's wallet, her favorite picture of her mom torn in half, her new leather jacket now full of cat hairs. This cat not only stinks, he's a thief as well. Still, the evening need not be a total waste. They order pizza, have some wine. She and her man talk; their moods improve, and she decides that it might be a nice time to kiss. She pulls the old yawn trick to get her arm around him, and just as she's ready to kiss him the cat jumps into his lap. "Oh, Pookie, Pookie, Pookie," her boyfriend says, giving himself over to the purring cat. "Damn lap cat," the writer says to herself, and leaves it at that. She has written a paper illustrating that cats are smelly, thieving, and middle class. She has fulfilled her thesis.
Now, you like this paper. It's got a great voice, and it's got humor. You feel, however, that the writer should refine the thesis. It has served the writer well in helping her to organize, control, predict, and define her essay; however, she needs now to consider how to choose words and a tone which will hook the reader and reel him in. You explain to the writer that her thesis can be humorous, that she can feel free to be extreme, because a funny, exaggerated thesis would suit this funny, exaggerated paper.
After some doodling and some dialogue, the writer comes up with the following thesis: "All cats should be exterminated because they are the stinking, kleptomaniacal darlings of the bourgeoisie." You laugh; you like it. Moreover, the thesis has given the writer an ending for her essay: she exterminates the cat in her boyfriend's microwave, convinces him to get a goldfish instead, and the two of them live happily ever after. The writer is happy. The tutor is happy. The paper works.
While you will likely not encounter a "cat" assignment at Dartmouth, this sort of experience with writing a thesis is a common one. Even when papers are more sophisticated than this one - even when the subject is Hitler's rise to power, or Freud's treatment of taboo - writers will often write a working thesis, one that guides them through the writing process. Then they will return to the thesis, sometimes several times before their paper is finished, revising it to better fit their paper's increasingly refined argument and tone.