HELP! Confusing question about conditional reasoning. Forum

[TEDC]

Hey guys/gals,

I am working my way through the Power Score Logic Reasoning Bible and came across this confusing mini-drill question on conditional reasoning. Perhaps the collective knowledge of TLS can help to better explain the reasoning behind this question.

The directions ask the reader to identify the sufficient and necessary conditions and the example is as follows:

The only way to achieve success is to work hard.

The book lists "achieve success" as the sufficient condition and "working hard" as the necessary condition. The book goes on to say that "only" modifies "way" and the "only way" refers to working hard (which is what I don't understand).


Thanks!
Ted

[truffleshuffle]

The only way to achieve success is to work hard.

Therefore, IF one achieves success, THEN they must have worked hard. Since you can only achieve success by working hard, and no other possible way, then achieving success is SUFFICIENT to show that hard work occurred, because it is the only possible way. Also, since you can only achieve success through working hard, it is NECESSARY to work hard in order to achieve success, because there is no other possible way.

[NaturalLawyer]

The only way to achieve success is to work hard.

Therefore, IF one achieves success, THEN they must have worked hard. Since you can only achieve success by working hard, and no other possible way, then achieving success is SUFFICIENT to show that hard work occurred, because it is the only possible way. Also, since you can only achieve success through working hard, it is NECESSARY to work hard in order to achieve success, because there is no other possible way.

The only thing I would add to this answer is that, the way it is worded, it might mislead one to think that working hard is also SUFFICIENT for success. But it is important to note that working hard is only a necessary condition, and not a sufficient condition for success according to the statement in discussion here.

So: If you want to obtain success, you must work hard. But working hard may not be enough for success.

Just like if you want to live in Los Angeles, then you must live in California. But living in California does not mean you live in Los Angeles.

[Sh@keNb@ke]

The Only ALWAYS ALWAYS introduces a sufficient condition. Only is an indicator of a necessary condition. Watch out for that sneaky The.

[TEDC]

The Only ALWAYS ALWAYS introduces a sufficient condition. Only is an indicator of a necessary condition. Watch out for that sneaky The.

Words to live by. Thanks to all for the help!

Ted

[PDaddy]

Hey guys/gals,

I am working my way through the Power Score Logic Reasoning Bible and came across this confusing mini-drill question on conditional reasoning. Perhaps the collective knowledge of TLS can help to better explain the reasoning behind this question.

The directions ask the reader to identify the sufficient and necessary conditions and the example is as follows:

The only way to achieve success is to work hard.

The book lists "achieve success" as the sufficient condition and "working hard" as the necessary condition. The book goes on to say that "only" modifies "way" and the "only way" refers to working hard (which is what I don't understand).


Thanks!
Ted

OVER THINKING IT. If you are successful, then you necessarily worked hard. Get it?

Success is sufficient. "Only" introduces the necessary condition at (almost) all times.

Only red cars get stopped constantly. If it gets stopped constantly, it's a red car.

Only if I earn enough money will I go skiing. If I go skiing, I earned enough money.

Here's a tricky one: "If only I was better looking, I could get the girl of my dreams."

In that case, "only" doesn't introduce the necessary condition.

When you use, "if only", it just means "if", so standard conditionals apply.

But if you use "only if", the word only introduces the necessary condition.

[PDaddy]

The Only ALWAYS ALWAYS introduces a sufficient condition. Only is an indicator of a necessary condition. Watch out for that sneaky The.

Words to live by. Thanks to all for the help!

Ted

Not true. Look at my example above. One caveat, the LSAT almost never uses "if only", but you should still understand how it works.

[Audio Technica Guy]

Also, you have to remember that sometimes only is a quantity qualifier.

As in If john only goes to the store, wanda will go to the movies. This means that if the single only thing John does is goes to the store, then wanda will go to the movies.