How would you negate this sentence? (PT63 S3 #11 B) Forum

[june2014]

What would be a correct way to negate this sentence?

People who attempt to diagnose their medical conditions are likely to do themselves more harm than good
unless they rely exclusively on scientifically valid information.


Is it
"People who attempt to diagnose their medical conditions are NOT LIKELY To do themselves more harm than good
even if they don't rely exclusively on scientifically valid information"

or

is it
"If people who attempt to diagnose their medical conditions don't rely exclusively on scientifically valid information,
then WE HAVE NO INFORMATION about whether they are likely to do themselves more harm than good"?

[gentlemanscholar]

I like the 2nd one.

[sfoglia]

Don't hold me to this, because I may be SO wrong, but now I'm trying to figure it out, too!

Okay, so you're supposed to break it down by idea, right? Look at the absolute minimum it would take to disprove the statement? What if we rephrase for clarity? And then what if we remove the massively confusing modifiers?

Unless they rely exclusively on scientifically valid information | people who attempt to diagnose their medical conditions | are likely to do themselves more harm than good.

Subject is people. Trigger is relying exclusively on scientifically valid information. Result is unlikely to do more harm.

Now to negate...

1. Unless they don't rely exclusively on scientifically valid information | people who attempt to diagnose their medical conditions | are likely to do themselves more harm than good.

That definitely negates, right?

OR

2. Unless they rely exclusively on scientifically valid information | people who attempt to diagnose their medical conditions | are unlikely to do themselves more harm than good.

We can rephrase this as equally likely or less likely to do harm. We don't know which. We just not not more, so either equal or less. This one also works, right?

So, I think it's the first one you posted.

[bjsesq]

What would be a correct way to negate this sentence?

People who attempt to diagnose their medical conditions are likely to do themselves more harm than good
unless they rely exclusively on scientifically valid information.

You're welcome

[sfoglia]

What would be a correct way to negate this sentence?

People who attempt to diagnose their medical conditions are likely to do themselves more harm than good
unless they rely exclusively on scientifically valid information.

You're welcome

Pahahahaha.

[Christine (MLSAT)]

From a practical perspective, either one would do the trick on this question. But the second one is the right way to think about it.

Negating conditionals is a little weird in practice. You cannot just negate the verb or relevant quantifier the way you might in a normal sentence. You are, essentially, calling the rule a lie.

I always imagine two little kids on the playground, playing Calvinball. One kid makes up a crazy rule. The other kids says "NUH-UH, that's NOT A RULE!"

Taking a simple version "All roses are red" translates to "If rose --> red." The negation would be "If rose --> no idea what color you are", NOT "If rose --> not red". This bad negation would imply that there are NO red roses in the world, which is going entirely too far. There could very well be lots of red roses in the word, after all, just not ALL of them. This is the entire basis for why we negate "All roses are red" to "some roses are not red" instead of "All roses are not red". (To be super picky, it should really be "it's possible that some roses are red".)

The introduction of likelihood doesn't change this basic process. If we said "If rose --> likely to be red", to negate it we don't actually need to go so far as to say that "If rose --> UNLIKELY to be red", all we need to say is that "if rose --> no information about the likelihood of being red".

Technically, all negations should really be expressed as mere possibilities, but it usually doesn't make a significant difference. We generally negate things like "Joe ate pizza last night" to "Joe did not eat pizza last night", and it works just fine. If we were being super pedantic, that negation should actually be "Joe may not have eaten pizza last night". But the first one is good enough for the negation test purposes, and frankly, a hell of a lot easier to think about.

With negating conditionals, though, the distinction matters more often, so you should be in the habit of always negating conditionals by saying "If X --> no idea about Y" or "If X --> could be Y or ~Y".

[sfoglia]

From a practical perspective, either one would do the trick on this question. But the second one is the right way to think about it.

Negating conditionals is a little weird in practice. You cannot just negate the verb or relevant quantifier the way you might in a normal sentence. You are, essentially, calling the rule a lie.

I always imagine two little kids on the playground, playing Calvinball. One kid makes up a crazy rule. The other kids says "NUH-UH, that's NOT A RULE!"

Taking a simple version "All roses are red" translates to "If rose --> red." The negation would be "If rose --> no idea what color you are", NOT "If rose --> not red". This bad negation would imply that there are NO red roses in the world, which is going entirely too far. There could very well be lots of red roses in the word, after all, just not ALL of them. This is the entire basis for why we negate "All roses are red" to "some roses are not red" instead of "All roses are not red". (To be super picky, it should really be "it's possible that some roses are red".)

The introduction of likelihood doesn't change this basic process. If we said "If rose --> likely to be red", to negate it we don't actually need to go so far as to say that "If rose --> UNLIKELY to be red", all we need to say is that "if rose --> no information about the likelihood of being red".

Technically, all negations should really be expressed as mere possibilities, but it usually doesn't make a significant difference. We generally negate things like "Joe ate pizza last night" to "Joe did not eat pizza last night", and it works just fine. If we were being super pedantic, that negation should actually be "Joe may not have eaten pizza last night". But the first one is good enough for the negation test purposes, and frankly, a hell of a lot easier to think about.

With negating conditionals, though, the distinction matters more often, so you should be in the habit of always negating conditionals by saying "If X --> no idea about Y" or "If X --> could be Y or ~Y".

Thank you so much. Such a clear explanation.