The essay thesis is the point that you are trying to make with your paper. It says to the reader "Here's the conclusion of the paper, now get ready for a bunch of facts to support it." Looking at it from the other direction, a thesis is a way to explain the importance of a bunch of facts.
Often you will just be given a topic. For example a common topic for high school persuasive essays is "Gun Control." It's an important argument that has lots of reasons for and against. Your job is to pick a side and defend it. Don't sit on the fence. Never write an essay that says "I'm for this, but also against it." You might acknowledge the legitimacy of the opponent's arguments, but you need to take a stand. Other times, the essay topic might be more complicated and you will have to tease out your thesis. (See the page on brainstorming for more ideas about gun control).
Some possible theses for a gun control essay could be:
Gun control laws are necessary for public safety;
The right to bear arms overrides any governmental limitation on gun ownership;
Guns have a legitimate use, so therefore it is unconstitutional to restrict their ownership;
Society has changed significantly since the constitution was written, therefore gun control is a necessary thing for government to do.
The thesis should show cause and effect, interpretation, or significance. You can fill in the blank for the following thesis statements:
A theme of (name of work) is (.....).
Important symbols in (name of work) are (...).
A cause of (___) was (_____).
Because of (_____), (_____) happened.
The importance of (_____) was (______).
Your thesis should be clear and direct. A reader once asked me: The sentence below is going to be my opening sentence in my introduction, to an essay on reincarnation. Is it good enough to grip the reader? "Reincarnation is a subject some people either reject, or think plausible." How did I reply? See answer here.
Why do you think Napoleon was able to gain power? Not only was he a shrewd politician, but after the reign of terror, the French people were happy to have a strongman who could take control of the country and give them relative peace. Thesis: The chaos of the Reign of Terror made the French people willing to have a strong leader who could unite the country. This is echoed in the Soviet Union of the 1950s and Stalin's iron grip. Thesis: The chaos of the Second World War made the people of the Soviet Union willing to have a strong leader who could protect the country. Just ask George Bush, whose re-election was virtually guaranteed by the 9-11 attacks. Thesis: The chaos of the 9-11 attacks made Americans desire a strong President who could protect the country. Fill in the blank: (_____) made (_____) happen.
If you can make this kind of statement, then you are half way to a good thesis statement. The next step is whether or not you can find some historical facts to back up your thesis. Was there chaos? Was the leader strong? These are the kinds of things you can show with a little research.
Let's say you were given the following topic for a history essay: "Napoleon and Nelson used innovative tactics in their battle at Waterloo but the ultimate outcome of the battle was inevitable due to cultural influences."
So you know that your thesis should have something to do with the differences between English and French culture. The professor probably prefers English culture to French since the English won the battle, but the thesis is still up to you. Your thesis could be: "The discipline imposed by the English public school system gave Horatio Nelson an advantage over the Jesuit educated Napoleon Bonaparte." Now your essay will consist of research showing:
a) that Nelson was educated in an English public school and;
b) that the teaching methodology in that school was disciplined, and finally;
c) the tactics used by Nelson reflected that discipline.
On the other hand, you might want to support the French and your thesis could be: "Having defeated the English in 1066 at Hastings, the French forces at Waterloo did not feel the need to again demonstrate their superiority and they let Nelson have the day." This might be a little harder to prove, but your research might show
a) the French reaction to victory in Hastings and;
b) how the French incorporated this into their cultural outlook, and;
c) how this outlook affected battle performance in the battle.
The point I'm trying to make is: Even when they give you the topic, they did not necessarily give you the thesis. The thesis is the theory which explains the relationship between the facts in your essay. It's really the evidence that you are thinking about the topic and can be worth up to 40% of your grade.
Often you are left to come up with your own topic. This can be difficult if you don't like the course at all. Try to find an aspect of the course which interests you and use that to point you toward your thesis. Remember, a thesis is just a way of explaining some bunch of facts.
You might do some background reading to try to come up with a thesis, but beware of piling up a lot of facts and then thinking you can infer a thesis from them. Your thesis will give you direction in your research, otherwise you are probably wasting your time.
OK, it's a little high school to write "It is the purpose of this essay to..." What you need to do is lay down some basic facts and arguments which relate to the thesis. Your thesis statement is a bold statement which is not footnoted but would ordinarily require backing up.
Fill in the blank for your thesis statement:
"The reason for..."
"An important implication of..."
"In this context ____ can be seen as..."
Your essay is the back up for the thesis statement. The thesis statement usually comes about 1/10 of the way into the essay. After your thesis statement, you plunge into the body of the essay, lining up your arguments to support your thesis.
Don't lose sight of your thesis statement. You should be able to look at your final essay and see how every paragraph helps to support your thesis. Often you will have more facts available than you can use. Your thesis helps you discriminate between which facts you will find most useful.