The use of And/Or

Hi everyone,

I recently composed a few short essays for my my TESOL classes and I had them proofread by a professional proofreader based in Cambridge. He made a few changes to my writing. However, I do not quite understand why he has made the following change...

(The topic of my essay: animal testing)

My original sentence: In other words, if animals were not available, we would not have any new treatments or drugs, and scientists would have to test in humans and kill unnecessarily.

The proofreader changed it to: In other words, if animals were not available, we would not have any new treatments or drugs, or scientists would have to test in humans and kill unnecessarily.

Could anyone help me out on this? IS my original sentence wrong? Or is it just not as good as the latter sentence? Do I have to use 'or' here to link the two sentences? I am so confused.

Thanks very much!!!

Hello!

*I AM NOT A TEACHER OR NATIVE.*

To me, both of the sentences are correct and meaningful but the meaning they convey are a little different.
"And" in your sentence paves the way for talking about a consequence while "or" in the second sentence addresses a choice.

I would use "or" in your sentence. When you use "and" you are proposing that both statements are true. But the meaning of your sentence is that we would not have any new drugs unless scientists do the testing in human patients. That is covered better by "or", Either we test drugs on humans or we won't have any new drugs.

MikeNewYork said:

I would use "or" in your sentence. When you use "and" you are proposing that both statements are true. But the meaning of your sentence is that we would not have any new drugs unless scientists do the testing in human patients. That is covered better by "or", Either we test drugs on humans or we won't have any new drugs.

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Hello.:-D
The topic is about "animal testing".
The underlined part should be "unless scientists do the testing on animals", shouldn't it?

seaview2007 said:

(The topic of my essay: animal testing)

My original sentence: In other words, if animals were not available, we would not have any new treatments or drugs, and scientists would have to test in humans and kill unnecessarily.

The proofreader changed it to: In other words, if animals were not available, we would not have any new treatments or drugs, or scientists would have to test in humans and kill unnecessarily.

Click to expand...

It's more a matter of logic than English.
If the proposition or argument that you are making is "If we are to have new drugs (X), then scientists must test on animals (Y) or scientists must test on humans (Z)" (If X, then [Y OR Z]), then this translates to "If [not-Y], then [not-X OR not-Z]".
Your sentence translates as If "[not-Y], then [not-X AND Z]. Simpy, it's not logical. But this isn't a logic forum, so I'll try to explain in English, which is probably more complicated.

1. It is not true that, if animals were not available we 1) would not have any new treatments AND 2) scientists would have to test humans.
2. It is true that, if animals were not available we EITHER 1) would not have any new treatments OR 2) scientists would have to test humans.
1. is not true because the absence of animals to test only means one of the following - we either go without new drugs OR scientists have to test on humans. 2. is true because only one of the conclusions is a necessary result of not having animals. If [not-Y], then [not-X OR not-Z].
Other logical conclusions can be derived from the original premises:
If X, then [Y OR Z] ->
If [not-Y AND not-Z], then not-X. (If scientists can't test on animals AND scientists can't test on humans, then we won't have new drugs.

Yes, English isn't always logical, but you have presented a logical argument in that form, and your argument is invalid.

No. If it were not permissible to test on animals, then scientists would need to test on humans.

tzfujimino said:

The underlined part should be "unless scientists do the testing on animals", shouldn't it?

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No, you have to read the whole sentence.

MikeNewYork said:

I would use "or" in your sentence. When you use "and" you are proposing that both statements are true. But the meaning of your sentence is that we would not have any new drugs unless scientists do the testing in human patients. That is covered better by "or", Either we test drugs on humans or we won't have any new drugs.

Click to expand...

I got your point! Thanks very much!