You will probably receive, or have received, the following feedback at some point: “Try to narrow your thesis.”
This may seem odd; a thesis isn’t something you can squeeze and shape. Can a thesis be ‘fat’?
The comment is an attempt to explain that you have bitten off more than you can chew.
In the typical 4 to 8 page high school or college argumentative essay, a thesis like “marijuana should be legalized” is way too broad for a successful essay. What can you (or even your professor) say about this topic that hasn’t already been said? So you might abandon the topic, or find a way to narrow it.
For instance, “marijuana in Akron Ohio should be legalized.” With this simple change we have focused the argument and helped make it more argumentative at the same time. Suddenly the question becomes one of local vs. State or Federal power (can a city make such a change?). Your reader is more engaged, because they haven’t seen this one before, and your research and logic can focus to much more specific issues than the original version.