Write out in standard form. Next say whether you think the argument is valid or
ID: 3216318 • Letter: W
Question
Write out in standard form. Next say whether you think the argument is valid or invalid. Prove an informal proof or counter example.
1. everyone now alive had two parents each of whom in turn had two parents. It follows that in our grandparents day there were four times as many people as there is today.
2. If our satellite photography shows the remains of abandoned towns and cities on the surface of Mars, then there was once intelligent life on that planet. But our satellite photographs show no sign of abandoned towns or cities on the surface of the planet. We can only conclude that there has never been intelligent life on Mars.
3. Either man are suoerior to women or women are superior to men. But men are not superior to women. So, it follows that women are superior to men.
Explanation / Answer
1. everyone now alive had two parents each of whom in turn had two parents. It follows that in our grandparents day there were four times as many people as there is today.
- Invalid.
Every person has 2 parents but then these 2 parents can have multiple kids as well so the number of persons were not exactly 4 times in the grandparents's time
2. If our satellite photography shows the remains of abandoned towns and cities on the surface of Mars, then there was once intelligent life on that planet. But our satellite photographs show no sign of abandoned towns or cities on the surface of the planet. We can only conclude that there has never been intelligent life on Mars.
- Invalid
A : photography shows the remains of abandoned towns and cities on the surface of Mars
B: there was once intelligent life on that planet
if A is true then B is true
if A is false, then B may be true or false.
that is why it is not necessary that there was no intelligent life.
3. Either man are suoerior to women or women are superior to men. But men are not superior to women. So, it follows that women are superior to men.
- Valid.
TRUE.
men are superior = M
women are superior = W
Either men are superior or women are : M or W = TRUE {this implies either M or W is true}
Mea are not superior : M = False
so W = TRUE {women are superior}
please upvote the answer.
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