in my experience, people use both, but in different contexts.
“in the mirror” tends to more often refer to a metaphorical “mirror”, typically when discussing self-reflection
- “I took a look in the mirror and decided to change my ways.”
“in a mirror” tends to refer most often to actual mirrors that exist in reality, not metaphorically
- “I looked into a mirror to fix my eyeliner.”
I’ve seen people use each interchangeably, but i would consider that a common mistake of style and form, not as a common valid usage.
A fair guess, but this isn’t one of those times when a grammatical error becomes normalized through common usage.
There is no grammar rule that separates speaking literally versus metaphorically in this case.
“You have something on your face; go take a look in the mirror” is just as grammatically correct in English as “You need to take a good look in the mirror and change your ways.”
I’ve explained why this is standard usage in English in my comment here.
“You have something on your face; go take a look in the mirror” is just as grammatically correct in English
yes, but only if you’re referring to a specific mirror. so, “go look in the mirror” would be appropriate if you’re also indicating to/pointing at a mirror, or there’s been a specific mirror under discussion already (or if the audience already knew there was only one mirror they could be referring to.)
also, it’s not technically a grammatical error, but one of poor style/form.
edit: also, i’m not a fan of the “using the grammar and spelling of a 3 year-old is valid because language is fluid!” argument. bad grammar and poor style/form are just that. just because doing so may be popular doesn’t magically make it “valid”. to me, that whole argument reeks of, “I’m not wrong for being ignorant, you’re wrong for pointing out my mistake-- so it’s magically not a mistake anymore so I can avoid acknowledging ever being wrong!”
Nope, as I explained in my other comment, it’s standard usage.
In English, we often use the definite article when speaking in general about a specific activity or action that involves a non-specific object. E.g. “go to the bathroom” or “catch the bus”, or “read the newspaper”. It’s not poor form at all.
