Yes, you are allowed to steal ideas. That's because you can't copyright an idea. And what I do with an idea might be very different from what you would do.
Now, there are some common sense boundaries. If I tell you I'm going to query a specific editor about an article on an upcoming event, and you quickly fire off an email to the same editor about writing an article on event, that is definitely a no no. And anything that has been published or produced is protected by copyright.
But on less specific things, stealing ideas is allowed. For example, if I read an article on how to raise great kids in a magazine, and I find that I have things to say that weren't said in the article, there's no harm in my writing another article on how to raise great kids using my perspective and my own examples. No, you can't combine three of the first author's points with two of yours. What you write has to be different, has to be uniquely yours. Other wise you're guilty of plagiarism.
So you write a totally different article, but with the same overall focus—how to raise great kids.
Now, what do you do with it? Well, unless raising kids is the primary focus of the magazine, I probably wouldn't send my article to the same magazine where you read the original. At least not for a few months. Why? Because they just published an article on that topic. And they likely won't publish a similar article for at least several months, probably a year.
