I’m going to draw a line between the words like and good. This is a distinction that is significant but often missed by theatre audiences. Using these terms interchangeably, especially when recommending a show to a friend, leads to confusion, wasted money, and most damningly, wasted time as your friend watches a play or movie they otherwise might have skipped.

The difference is this: If you say you like something, you should be referring to your subjective self. You are revealing a glimpse into your life experience and your thoughts about the world; the elements in your life have configured in such a way that the show you just watched has moved you, personally, to like it. Perhaps the story was about a horse and you used to own a horse, or perhaps you love singing (especially coupled with dancing), so almost every musical appeals to you. Whatever the reason, understand that when you use the play as a springboard to talk about what you like, you are pointing at information about you instead of the play.

When saying a play is good, what you should mean is that, discounting your personal affinity for singing horses, the production successfully accomplishes whatever it set out to do. The story works. And when you go on to support your assertion, you should be pointing to facets of the production, not pointing at information about yourself.

At this point, I’d like to be clear that like and good both have their place. Deciding how to frame your talk depends on what you are trying to accomplish. If you and your play-going companion are sharing and learning about one another, talking about what you like is very useful. But if someone asks you if a play is worthy of their once weekly, babysitter-assisted, date night out of the house, they are probably asking for feedback on the play itself—leave your dead childhood horse out of it.

This confusion arises when vanity gets in the way and we fool ourselves into thinking that if we like something then it must be good because, after all, we have taste. Others may not have taste, but we certainly do, and people with taste couldn’t possibly like something that isn’t good. This line of thinking is a trap (obviously just liking something doesn’t make that thing good), but it does raise the question: How do we know if a play is good?

Let’s start at the beginning, with Aristotle. Father of all modern Western theatrical criticism, his ideas have influenced critics and dramaturges the world over, for centuries. In Aristotle’s Poetics he addresses this question of “goodness” by breaking a production into component parts and ranking each part in order of its import to the play as a whole. His list, in value order, is: Plot, Character, Theme, Language, Music, and Spectacle. So, according to Aristotle, if a show focuses on spectacle to the detriment of plot, then objectively speaking it’s not as “good” as it could be.

Let’s look to a recent spectacle-driven film for an example. Transformers: Dark of the Moon is an action film whose main characters are robots that fight one another in many locations... damaging many things. Obviously, cutting-edge special effects are a cornerstone of this film. However, despite its excellent spectacle, the movie was panned. It received an overall score of 36 (out of 100) on Rotten Tomatoes, and the site published this summary of the critical response: “Its special effects—and 3D shots—are undeniably impressive, but they aren’t enough to fill up its loud, bloated running time, or mask its thin, indifferent script.” This is Aristotle in action. Special effects, no matter how impressive, aren’t enough to make something good.

I can hear some readers stirring because they didn’t think Transformers was all that bad. Perhaps you saw it and liked it, maybe even bought it. This brings me back to my main point—liking something doesn’t necessarily mean it’s good. Your ownership of the Transformers DVD is evidence of nothing except that you LIKE a movie.

Now Aristotle goes into further, disputed detail about what separates good plays from bad, but this basic framework has stood the test of time and is often cited by industry professionals attempting to determine whether a piece may be labeled successful. However, there are other qualities to consider. The following comes from my experience working in the new play development department at Arden Theatre Company under award-winning dramaturge Edward Sobel. This is a place where hundreds of unpublished scripts cross your desk; if you use your gut to judge them instead of objective criteria, groundbreaking masterpieces will be ignored.

What I learned at that office is that, in general, good plays begin with a late point of attack. That is, they begin as late into the story’s action as possible. Good plays contain characters with strong needs who face obstacles to those needs—both internal and external. Their language is action-oriented with dialogue that attempts to accomplish a character’s strong objectives. And the language creates a consistent world for the characters to exist in, with each character’s voice being distinctly written.

So, in summary, skilled incorporation of plot, character, theme, language, music, and spectacle (à la Aristotle), plus a late point of attack, strong character objectives, and consistent action-oriented language—these are the objective guidelines the Western world uses to judge the success of a piece. While these are not the only criteria, they are major ones.

And remember, if a production runs afoul of these guidelines, you might still like it. But for the sake of everyone’s money and time, be willing to look beyond your own affinities and talk… about the play.