2.5 The Importance of Defining a Thesis

Once you have determined a specific focus for the argument, then you need to develop an opinion about that focus. In other words, you need to present an argumentative opinion about the narrowly defined subject matter you have selected.

This point is critical. You cannot base an argument merely on the focus you have defined. You must organize an opinion about that focus, something we can argue about. This opinion is called the thesis, and it is the single most important sentence or series of sentences in the entire argument.

For example, you cannot base an argumentative essay on teenage alcoholism in BC or on Ophelia in Hamlet or on the distribution of drugs in school. You must base the essay on an opinion about one of those. And, in general, the sharper the opinion and the more energetically you express it, the clearer the thesis will be, both to you and to the reader or listener.

The thesis should answer the question: What precisely is the presenter of this argument trying to persuade me to believe? If that is not clear, then the argument's central purpose is fuzzy or missing. So you need to take particular care to conclude the introduction with a precise definition of your thesis.

When you set out to do this, remember what we discussed in the previous section, namely, that certain statements do not make good arguments, because there is nothing we can usefully dispute in them. Make sure your thesis does not fall into this category (a great many students weaken their argument fatally by presenting a very poor thesis).

Notice, for example, that the following statements would make very poor thesis statements, because they are not sufficiently argumentative; they state matters which we can quickly confirm by an appeal to the text or to an existing authority:

1. Acid rain hurts fish.

2. Polonius is Ophelia's father, and when he dies, she goes insane.

3. Teenage drinking is very common in BC.

4. Bob Dylan started writing songs early in the 1960's.

These sentences are useless as thesis statements, because they present nothing we can usefully argue about. If that's all you offer at the end of your introduction, then the reader is going to be very puzzled about why you are striving so hard to argue about something obvious. Notice the difference between the above statements and the following.

1. Acid rain is the single most important threat to our quality of life, and thus we must undertake decisive action against it immediately, no matter what the cost.

2. Polonius's treatment of his daughter reveals clearly just how poisonous the emotional climate of Elsinore really is. His attitude to life is the source of much of the evil in the court.

3. Teenage alcoholism in BC is a vastly overrated problem. If there are difficulties, these have been exaggerated in order to scare us into thinking we are facing a new crisis.

4. Bob Dylan's early lyrics introduced the most significant changes in song writing since the early days of Tin Pan Alley. In one way or another, they have decisively influenced almost every other major song writer in North America ever since.

These statements put something argumentative on the table. We can easily disagree (or be reluctant to be persuaded), and the writer is going to have to work to convince us. Such statements do not simply announce a matter of fact about which we cannot argue significantly.

If you don't set the essay up with a clearly argumentative thesis, then the logic of the argument will be defective, because the reader will not be clear about what you are trying to establish. Please make sure you understand this key point. The failure to establish a good thesis is the single most important logical error in student essays.