X=y but does y=x?

Question

Wile talking to a friend we started talking about how control equals confidence, she wanted to find a symbol to show that not just control = confidence but as they said visa versa.

She got this answer from someone, you don't need to show that both equals each other because its self explanatory.

Their expansion: if x=y then y must =x.

going by there logic

My example: all killers are people so all people must be killers.

is my example wrong or am I right

Answer 1

This is all about subsets.  Think of killers in a small circle within a larger circle of people.  So all killers are people, since they're withing the larger people circle, but not all people are killers since the large circle doesn't fit within the smaller circle.

It's good to see you're exercising your brain and sharpening your logic.  Keep it up.

Answer 2

THat makes no sense. Its like saying that nothing is better than paradise but a ham sandwhich is better than nothing. So basically oyur saying that a ham sandwhich is better then paradise.

Answer 3

You are confusing = (equality) with => (implies).

x=y means x equals y. They are the same. Therefore y=x.

Your proposition would say that "All killers are people" means "killer is the same as person". Clearly not the intention of the statement.

In logical terms, "All killers are people" means "killer => person". That is "if someone is a killer, they are a person". To write this the other way round would be "not person => not killer" because if all killers are people, something that is not a person cannot possibly be a killer.

In logical terms, the equivalent statements are:

killer => person

not person => not killer

Answer 4

you're correct. although in math, x=y and y=x.

Answer 5

But animals kills do ..and so do poisons that aren't even made by man...I would think that you need something on each side that is equal to do what you say.But I'm just guessing. I was never any good at algebra. I do think that you should have put this question in the Alternative Section though. This is the Paranormal Section. I would say that control is false confidence. I think people without confidence have to have control to cover their lack of confidence. Maybe you're as confused by my answer as I was by your question. lol

Edit..OOPS !! Sorry!! I thought you were in the Paranormal Section. I'm the one in the wrong Section ! lol Sorry , again! No wonder I didn't understand your question.!

Answer 6

this is a logic question.

Are dogs are animals therefore

all animals are dogs..???

hmmmm??  

I

Answer 7

I beleive your logic is wrong, but it may just be an opinon kind of thing

Answer 8

In answer to your initial question:  Yes, but that is algebra which is very clear cut. If x has the identical value of y, then y has the identical value of x.

The rest of it is rather more of a semantic discussion.

Your example is wrong.  For a start, not all killers are people.

Overlooking this minor point, if all killers are people you can't surmise that all people are killers because you don't have enough information about the larger set.

Control doesn't equal confidence. Control *can lead to* confidence but that is not saying that they are the same thing.

Similarly, confidence can lead to control, but again this doesn't imply that they are the same thing.

It's like saying that a bed and sleep are the same thing.

Sleep may lead you to bed, or indeed being in bed may lead you to sleep, but they are not the same thing; they are not EQUAL.

Answer 9

= can only be used if the terms are equal in every way.  You can't put all killers = people, that doesn't make any sense.  You have to say all killers ARE people, that is, all killers share some common aspect, ie they are all people.  However, they are not alike in every way so you cannot say all killers = people therefore all people = killers.  You can say all killers are people therefore 'people = all killers', that is logical.

Answer 10

Well in math, there is a difference between = and = with three lines.

With three lines means equivalent, and = means equal. = means the two expressions are the same under current circumstances, and equivalent means the two sides of the evaluation must always be the same no matter what.

I guess you can just say something == somethingelse to mean equivalent, but that symbol is the symbol used to denote "equal to" in most programming languages.

Answer 11

If by your reasoning, then

all animals are people,

and so they can kill

because they are animals,

because.......people are animals.....

Answer 12

"Killers" and "people" are sets (not numbers or other single entities), so the notion of "equals" has to be treated differently.

For example, the set of people can be considered a large circle, and the set of killers a smaller circle lying within this. Thus, everything inside the smaller circle is automatically inside the larger one (i.e. all killers are people), but there are things inside the larger circle that are NOT inside the smaller circle (i.e. there are some people who are not killers).

For two sets to be "equal", they have to have exactly the same members, and neither set can have "extra" members.

The equals sign, when applied to numbers etc, of course runs both ways, but set theory has notions like "... is a subset of ... " and "... contains the subset ..." that complicate matters slightly.

Answer 13

Mathematically your correct that all people must be killers if all killers are people.

I have seen some very funny things like that argued with mathematical concepts.

The flaw is that you are applying mathematical concepts to things that do not fall under the category of mathematics and thus the argument might look good on paper, its really rather illogical when you use reason outside of mathematical logic.

Answer 14

well, i suppose it should differ from maths and real life. but maybe people are all killers! like they probably have killed an insect or something XD

but i don't think everyone is a killer in the sense of a killer bring someone who kills PEOPLE.