Is it rude to trick someone into showing that they lied to you?

[AllTheThings]

Is it rude to get someone admit that they have lied to you by tricking them?

For example, asking them questions about the incident and waiting until they mess up an important detail.

Ex: My grandmother was sent to the hospital after a fall, but my dad suspected that she had put herself there on purpose to get sympathy and hadn't actually fallen by accident. He questioned her about how she had fallen, and caught her in a lie when she couldn't remember whether she was supposed to tell him or the hospital staff that she had hit her head when she fell. (She hadn't hit her head, but wanted to tell my dad that she had so that he would worry more. She didn't tell that to the hospital staff because she didn't want to actually be kept in the hospital).

Being truthful, yet misleading:

Person 1: "So you are the CEO's best friend? Isn't Alex a great guy?"
Person 2: "Yeah, he is! So since I'm such great friend of the CEO, could you do me that favor please?"
Person 1: "Alex is a woman."   
Person 2: 

Or even outright lying to them:

Person 1: "I hate Bob! You hate Bob too, right? Isn't he such a jerk? I wish someone would teach him a lesson!"
Person 2: "Then you'll appreciate this. I just stole all the cookies from the cookie jar and framed Bob!"
Person 1: "Well I'm actually Bob's best friend, so I'll be sure to tell everyone what you just said to me."
Person 2: 

Are any of these approaches to get the truth rude? I'm talking only about things where the lie actually matters and could cause a problem. Not something stupid and none of your business like suspecting that your friend went to the adult store when they actually said they were getting groceries and trying to get them to admit where they really were.

[JenJay]

I think the risk you run with the more aggressive tricks is in getting tangled up in your own deception and becoming part of the problem. I'm a fan of the old "give them enough rope" technique. I'd ask direct questions and then let the person paint themselves into a corner. Getting it down in email is even better. What your grandmother did is also passive-aggressive and I deal with that by ignoring the insinuations and dealing with the facts. I would have said "That's scary, Mom. We need to tell the doctor that you hit your head. I'll go get someone right now..."

[Sharnita]

So you catch them and then what?  What do you do from there? In the scenarios you describe I can't imagine how that would help.

[Zilla]

If they are chronic liars, then yes I might do it once and request they stop lying to you.  But I would also be prepared to walk away, once a liar always a liar.
 

[AllTheThings]

So you catch them and then what?  What do you do from there? In the scenarios you describe I can't imagine how that would help.

In the first scenario, my dad now knew that his mother had lied and did not give her the attention she wanted. Hopefully, this will stop her from trying something like this again.

In the second scenario, you don't get in trouble from your boss by letting someone claiming to be their friend do something (like bypassing other channels and getting them on the phone).

In the third, you can now tell everyone that Bob is innocent and that he was framed.

So they definitely can solve the problem, but I'm wondering if these techniques are rude, as they all involve tricking people.

[AnnaJ]

So you catch them and then what?  What do you do from there? In the scenarios you describe I can't imagine how that would help.

This - I don't understand the purpose of spending the time and energy 'outing' liars.  Would your father not come to the hospital if your grandmother didn't hit her head?  If someone claims they know your boss and they don't, what does it matter? 

People who lie constantly get caught eventually, and this attitude strikes me as massively offensive when someone is not lying.

[AllTheThings]

So you catch them and then what?  What do you do from there? In the scenarios you describe I can't imagine how that would help.

This - I don't understand the purpose of spending the time and energy 'outing' liars.  Would your father not come to the hospital if your grandmother didn't hit her head?  If someone claims they know your boss and they don't, what does it matter? 

People who lie constantly get caught eventually, and this attitude strikes me as massively offensive when someone is not lying.

Outing liars can matter because things can go bad for you if they are not caught. Yes, if my dad had known from the start that his mother had lied he would not have gone to the hospital for her, and told her to deal with everything herself.

If you let your boss's "friend" talk to them on the phone and it turns out they are a salesman, the boss might get angry at you.

I outed a liar once by misleading them. My coworker at a daycare claimed I had left early, leaving a bunch of kids alone. From previous interactions with her, I knew that she hated me because she wanted someone else to get my job. Also, she never came to check on those allegedly left alone children, which led me to believe she had made it up on purpose. So I said to her, "Lot's of people drive beige toyota camrys, are you sure it was me you saw?" She said yes, that she had seen me get into my beige toyota camry and leave early. I responded that it couldn't have been me, as I didn't have a car like that. I said that in front of the boss, who knew that the other woman was a liar in a way that me just protesting my innocence wouldn't have. Maybe it was rude, maybe it wasn't under the circumstances since she made such a serious accusation, but it was certainly effective.

[SamiHami]

I think if someone is lying directly to me, they are the rude one. I wouldn't fault someone for outing a liar.

[Sharnita]

Honestly, a lot of the examples you bring up don't seem all that conclusinve and come off as bullying to me.

Maybe Grandma lied to get sympathy.  If she has a history of doing that then dad might not want to visit her, proof or know.  Bur elderly people get confused.  People who have been injured might not remember the details.  In another thread we discussed the confusion some patients experience in the hospital.  SO Grandma answering your dad's question "wrong" is not conclusive proof of anything IMO. 

If you think somebody is lying about knowing the boss to get access to the workplace then why not just call the boss?  That would provide more definitive information anyway.

[AllTheThings]

Honestly, a lot of the examples you bring up don't seem all that conclusinve and come off as bullying to me.

Maybe Grandma lied to get sympathy.  If she has a history of doing that then dad might not want to visit her, proof or know.  Bur elderly people get confused.  People who have been injured might not remember the details.  In another thread we discussed the confusion some patients experience in the hospital.  SO Grandma answering your dad's question "wrong" is not conclusive proof of anything IMO. 

If you think somebody is lying about knowing the boss to get access to the workplace then why not just call the boss?  That would provide more definitive information anyway.

In my grandma's case this definitely wasn't bullying. She's as sharp as a tack, and I think the only reason why she messed up was because my dad is a lawyer and knows how to do this kind of thing. She admitted that she had made it up to get sympathy. She had done this kind of thing before. The timing of this incident was also extremely suspicious. She also pretends to have dementia, so this has been an ongoing problem. My dad is a nice guy, he wouldn't accuse someone of checking themselves into a hospital on purpose unless he had a very good reason to.

Sometimes you can't just call up the boss, especially in a huge company. This is also the type of place where a bad call getting through could get you in the most trouble.

I could see how these actions might be rude since they involve deception, but I don't really see how any of them involve bullying.

[MrTango]

The Example with your grandma, not necessarily rude.

The other two examples you gave are rude because in both examples, Person 1 is lying.

Even the question "Isn't Alex a great guy" would be a lie if the person asking knows that Alex is a woman, as it is said with intent to deceive.

[AllTheThings]

The Example with your grandma, not necessarily rude.

The other two examples you gave are rude because in both examples, Person 1 is lying.

Even the question "Isn't Alex a great guy" would be a lie if the person asking knows that Alex is a woman, as it is said with intent to deceive.

Technically, not a lie (although there is definitely an attempt to deceive). Yes a reasonable person would assume that Alex is referring to the boss, but Alex could in theory be anyone.

[Sharnita]

The Example with your grandma, not necessarily rude.

The other two examples you gave are rude because in both examples, Person 1 is lying.

Even the question "Isn't Alex a great guy" would be a lie if the person asking knows that Alex is a woman, as it is said with intent to deceive.

They all come off as a bit self congragulatory and ego based to be honest.  Kind of like "Look how cleverly I trapped you"

[Lorelei_Evil]

Agreed.  It's entrapment and mean spirited at that.

[Sootikin]

So you catch them and then what?  What do you do from there? In the scenarios you describe I can't imagine how that would help.

This - I don't understand the purpose of spending the time and energy 'outing' liars.  Would your father not come to the hospital if your grandmother didn't hit her head?  If someone claims they know your boss and they don't, what does it matter? 

People who lie constantly get caught eventually, and this attitude strikes me as massively offensive when someone is not lying.

Outing liars can matter because things can go bad for you if they are not caught. Yes, if my dad had known from the start that his mother had lied he would not have gone to the hospital for her, and told her to deal with everything herself.

If you let your boss's "friend" talk to them on the phone and it turns out they are a salesman, the boss might get angry at you.

I outed a liar once by misleading them. My coworker at a daycare claimed I had left early, leaving a bunch of kids alone. From previous interactions with her, I knew that she hated me because she wanted someone else to get my job. Also, she never came to check on those allegedly left alone children, which led me to believe she had made it up on purpose. So I said to her, "Lot's of people drive beige toyota camrys, are you sure it was me you saw?" She said yes, that she had seen me get into my beige toyota camry and leave early. I responded that it couldn't have been me, as I didn't have a car like that. I said that in front of the boss, who knew that the other woman was a liar in a way that me just protesting my innocence wouldn't have. Maybe it was rude, maybe it wasn't under the circumstances since she made such a serious accusation, but it was certainly effective.

The first time you told the camry story here you said your boss just said that your co worker must have been mistaken and outing her as a liar didn't save your job since you lost it two weeks later.

I don't think misleading or tricking someone to make a point is a particularly useful tactic.