This video tutorial presents exercises 1E numbers 11 and 12
from chapter 1.
In these exercises we are asked to determine
whether the following arguments are best classified as being
deductive or inductive.
We're to explain our answers.
Here are the arguments.
Number 11, antibiotics have no effect on viruses.
You have a disease that is caused by a virus.
You are taking the antibiotic Q. Thus,
the antibiotic you are taking will
have no effect on your disease.
And argument 12.
Some antibiotics are effective for treating
certain bacterial infections.
You have a bacterial infection.
You are taking the antibiotic Q. Thus,
the antibiotic you are taking will
be effective in treating your bacterial infection.
Let's look at number 11 first.
We see one indicator word, "thus."
So we know that the final statement is the conclusion.
The preceding statements are that the premises.
Rewriting the argument, we get first premise,
antibiotics have no effect on viruses; second premise,
you have a disease that is caused
by a virus; third premise, you are taking the antibiotic Q.
In conclusion, thus, the antibiotic you are taking
will have no effect on your disease.
Is it deductive or inductive?
Well, if the first premise is true,
then no antibiotic has any effect on viruses.
If the second and third premises are true, then
you really do have a virus and you're taking an antibiotic.
So, assuming that all three of the premises are true,
then the conclusion has to be true.
In other words, it is necessarily true.
That means this argument is deductive.
Looking at number 12 now, we also
see the same indicator word, thus.
Rewriting the argument, we get premise 1,
some antibiotics are effective for treating
certain bacterial infections; premise 2, you
have a bacterial infection; premise 3, you
are taking the antibiotic Q; and the conclusion, thus,
the antibiotic you are taking will
be effective in treating your bacterial infection.
Is this argument deductive or inductive?
Let's work through what the premises are telling us.
If the first premise is true, then only some antibiotics
are effective for treating certain bacterial infections.
Knowing that you are taking a specific antibiotic Q
does not guarantee that it is one
of the effective ones in treating
the bacterial infection that you have.
Therefore, the conclusion only follows with some degree
of probability.
That being so, the argument is best classified as inductive.
In summary, argument number 11 can
be understood as a deductive argument,
while number 12 is best understood
as an inductive argument.