When you use another writer's intellectual property--language, visuals, or ideas--in your own work without giving proper credit to that person, you commit plagiarism.
Pretty simple, right? And I bet you didn't realize that this description of plagiarism is itself plagiarized: I took it word for word right from Diana Hacker's A Writer's Reference (Bedford/St. Martin's). I did make a few changes. I substituted "writer's" for her "author's," I left out some of her statement, and I added "to that person," but these minor changes in no way get me off the hook. I used Diana Hacker's language and her ideas without giving her credit. I passed them off as mine. I stole them, to put it bluntly, and that constitutes intellectual theft. If I used Hacker's definition in public--in a blog post, a speech, or an essay--and didn't give her credit, I would add fraud to theft.
The first time I ever taught a Shakespeare course at the University of Washington in Seattle, I discovered a wonderful example of plagiarism. I had been preparing to teach this introductory course for some months, but a fair amount has been written on Shakespeare's plays and I was barely keeping one week ahead of my class as I continued to read up on the plays I was teaching. Then the term papers came due. As I started to read a student's paper on The Winter's Tale, I had a sense of deja vu: this was very like something I'd only read a week or so ago. I reached over to the stack of books on my desk and pulled out E.M.W. Tillyard's Shakespeare's Last Plays, turned to the chapter on The Winter's Tale, and there it was: the term paper copied Tillyard word for word, and without any acknowledgment.
I wrote at the end of the paper, "This is an excellent paper, but of course Tillyard is an excellent critic. Because you have plagiarized without any acknowledgment of your source, your grade is F. Please see me if you have any questions."
A young woman promptly came to see me. I have long since forgotten her name; I'll just call her Jane Doe. Jane Doe kept repeating that she just couldn't understand her grade. Finally, in some frustration, I said, "Miss Doe (this took place many years ago, remember), I can't understand why you don't understand. You copied your paper word for word, paragraph for paragraph, from Tillyard's book, Shakespeare's Last Plays, and you never acknowledged him as your source. This is plagiarism, and that is why I am failing your paper."
At this, Miss Jane Doe burst into tears. I silently handed her a box of tissues. Finally she said, "Oh, Professor Cox, I copied this from my sorority's file of term papers. But if I had known it was plagiarized, I never would have copied it!"
We now have the spectacle of the Trump campaign denying that Melania Trump's speech on July 18th was in part plagiarized from the speech given by Michelle Obama in 2008. It is bizarre to have a possible First Lady quoting from the current First Lady (as opposed, say, to Mrs. Hoover), but all anyone has to do is look at the two passages side by side to realize that part of the speech did plagiarize both language and ideas without acknowledgment. Melania Trump reportedly told NBC's Matt Lauer before she gave the speech, "I wrote it. And with as little help as possible." Oh, right. But who wrote the speech is not the issue, it's who plagiarized it. Even more bizarrely, the people running Trump's campaign apparently thought that that she/they could get away with this. These days, all you have to do to identify plagiarism is type a phrase or two into a software program.
Most bizarre of all is the level of dishonesty on display. For the Trump campaign initially to deny that plagiarism ocurred is beyond belief. Paul Manafort, Trump's campaign manager, came up with the statement, "We don't believe there is anything in that speech that doesn't reflect her thinking"--as if thinking and plagiarizing were synonymous. The opposite is more likely: people plagiarize to avoid thinking. And Chris Christie bloviated that ninety-three percent of the spech is completely different--as if plagiarizing only seven percent of the speech made the problem somehow recede into something acceptable. At least Miss Jane Doe acknowledged (albeit comically) that she had copied someone else's work. She ended up passing my course. So far, Donald Trump's campaign managers and staff writers deserve an F for plagiarism.