Editor: Below is a insightful user comment on Top 10 English Grammar Myths and Superstitions in Essay Writing which is worth to be republished as a post here.
Whoa! Whoa! Whoa!
Let's make sure we understand this bit on using contractions. There's no rule that says you can't use contractions in essays, but we need to understand something a little deeper.
In language, there is formal and there is informal. Magazines and newspapers are informal, they written as if to hold a conversational tone. Having been an editor in chief for three large newspapers and a contributor to scholarly journals, I can say that I know a bit on this.
Magazines and newspapers use informal writing because not only does his help readers feel a kinship, but it also saves expensive printing space to have shorter words. They live by the motto "short is better than succinct" and therefore contractions are better than formal writing.
Scholarly journals and academic research is formal, meaning that you show a respect to not only the field of study but to those who paved the road in research before you. You wouldn't walk up to the president of United States and greet him with "what's up dude." You would walk up and say "Mr. President."
Essays can be informal and formal. Anyone who tries to claim that there is no need to use formal language in academic or other formal writing is flat out a lazy writer and has no business giving advice on writing any kind of essay. Anyone who knows how to decipher the difference between formal and informal will always write better with a formal voice than someone who doesn't understand the differences and who writes informally.
Make no mistake, Magazines and newspapers are out to save space and time and they are not formal writing in the least degree. Don't be a lazy writer. And don't compare a medium that is designed to be written on a fifth grade level (newspapers) to those that are written for professionals and specialists with terminal degrees.