I am a liar

Logic Level 2

You come across a stranger, who looks you in the eye and says:

Is the stranger lying or telling the truth?

He is telling the truth, that statement is always true. He is lying, that statement is always false. That statement is neither true nor false. It is not possible for any person to say that.

View wiki
Chung Kevin by Chung Kevin , 45, Australia

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

5 solutions

The two possibilities are:

1)1+1=3 or

2) he is lying.

Case 1: He says the truth. If his statement is true then either

1) or 2) is true.

Since 1) is invalid we conclude that 2) is valid. But this is a contradiction.

Case 2: He is lying:

The fact that he is lying makes the whole statement true since 2) is satisfied. So, there is again a contradiction.

2 Helpful 0 Interesting 0 Brilliant 0 Confused

But I think if either of the statement is true then the guy is telling you a truth ....

Baldev Rinwa - 5 years, 6 months ago

The correct answer should be A. Naturally when you're dealing with true/false statements like that, you can analyze it through Boolean Algebra, and treat the "or" in the question as the logical operator or. "1+1=3" is false, and "I am lying to you right now" equals true because of the first statement, and "false or true" is equal to true. Therefore, he is telling the truth.

Cody Childers - 5 years, 6 months ago

We were asked whether he was saying truth or not. He said that either 1+1=3 or I'm lying. Now since 1+1=3 is a lie, doesn't that mean he said the truth.

Pious Padmakar - 5 years, 6 months ago

Log in to reply

As I think ,he is giving you two options and as long as one of them is true ,he is telling the truth .....its like i m saying that the person in the corner is either boy or a girl ....so as long as that person is not transgender ,I am telling the truth . :)

Baldev Rinwa - 5 years, 6 months ago

When we use either at certain conditions it means one of the two condition must be true. 1+1=3 is false so the second condition must be true it means that he is a lier. So the correct option is he is lying that statement is always false

Muhammad Zia - 5 years, 6 months ago

This is an OR statement. Since one of the two constituents of his statement is true, then the statement is true.

Isaac Thomas - 5 years, 6 months ago
Prasit Sarapee
Nov 22, 2015

1+1=3 is false.

Let P := False or x.
False or x :=x ---> P:= x
if x is true then P is true
if x is false then P is true
so P is is neither true nor false.


0 Helpful 0 Interesting 0 Brilliant 0 Confused
Elessia Hall
Nov 22, 2015

Since there is is no "if-then" to the statement, there is no truth value.

0 Helpful 0 Interesting 0 Brilliant 0 Confused

Why should that make a difference? "I am a catfish," is false.

Whitney Clark - 5 years, 6 months ago
Aaryash Nayak
Nov 22, 2015

If he says the truth, it means 1+1=3, but it also means that the next statement - "I am lying to you right now" will also be true leading to contradiction that he is lying. Therefore the statement is neither true nor false.

0 Helpful 0 Interesting 0 Brilliant 0 Confused

ohk please explain me one thing that if i ask you that i'll either give you 5000 rps or a mobile phone ....what will you do , take 5000 n then ask for mobile also ??? I don't think so . So i don't think there is any valid explanation for this answer .

Baldev Rinwa - 5 years, 6 months ago
Mistah Jam
Nov 22, 2015

U dont have enough information to conclude whether the statement is either true or false. So it is neither true or false.

0 Helpful 0 Interesting 0 Brilliant 0 Confused

When we use either at certain conditions it means one of the two condition must be true. 1+1=3 is false so the second condition must be true it means that he is a lier. So the correct option is he is lying that statement is always false

Muhammad Zia - 5 years, 6 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...