Logic Part II
2: Premises – “Giving good reasons.”
When listening to others, we cannot concentrate only on our own feelings and reactions
- We must listen to what they are saying to determine whether it is true, regardless of how we feel
- History’s greatest oppressors have been able to influence people’s emotions to distract from wicked and destructive schemes.
- To avoid being manipulated and harmed and to protect others, we must determine the truth of what is being said.
“One of the best remedies for bad reading and writing is good logic, especially the analysis of propositions. For thinking clearly, expressing your thoughts clearly (in writing or speaking), and interpreting another’s expressions (written or spoken) clearly are three arts that are very closely allied; no one of them can be done well without doing the other two. And the part of logic that is most directly related to this is the part that studies propositions.” (Peter Kreeft)
Premises may also be called propositions.
We write a proposition as a declarative sentence.
Ex.: All the students at Buckeye Central are human.
We must identify in every proposition a subject and a predicate.
Subject – what we are talking about
Predicate – what we say about the subject
Propositions are either true or false.
Finding the truth is the main goal of logic, so finding true propositions is essential for finding truth.
What is truth?
Correspondence with reality:
A thought matches the thing
The mind matches the world
“Telling it like it is.”
“If a man says of what is that it is, or of what is not that it is not, he speaks the truth” - Aristotle
Truth is not:
What is practical
To convince me that it is practical, you have to appeal to reality
What benefits you
To prove that it benefits you, you must show how it benefits you in reality; you must measure the benefit by some real standard
Your opinion
To persuade me to agree with you, your opinion must be based on some real value that exists
Simplifying premises
To make an argument easier to understand, you can re-phrase each premise into one of the four classic logical forms:
- Universal affirmative
“All men are mortal.”
- Universal negative
“No men are mortal.”
- Particular affirmative
“Some men are mortal.”
- Particular negative
“Some men are not mortal.”
Example: Kittens
- “All kittens are cats.”
- “No kittens are dogs”
- “Some kittens are tabby.”
- “Some kittens are not cute.”
The rules of deductive arguments are always and everywhere true.
Rule 1: Whatever is universally true of a subject must be true of everything contained in that subject.
Example: All men are mortal, I am a man, therefore I am mortal.
Rule 2: Whatever is universally false of a subject must be false of everything contained in that subject.
Example: No kittens are dogs, Fluffy is a kitten, therefore Fluffy is not a dog.
Rule 3: Two things identical with the same thing are identical with each other.
Example: Ashley is my sister, Ashley is married to Brandon, therefore my sister is married to Brandon.
Rule 4: If one thing is identical with something that a second thing is not identical with, then the first and second things are not identical with each other.
Example: No men are angels, I am a man, therefore I am not an angel.
Rule 5: A thing cannot be the opposite of itself.
Example: A magnetic pole is either positive or negative.
Rule 6: A thing either has a certain attribute or it does not have it.
Example: “Is you is or is you ain’t my baby?”
In other words, a premise is either true or false.
Logical Mistakes – regarding premises
Mistakes in Connecting the Facts
- Making a Hasty Generalization.
“The Browns keep losing this season. They’ll always be losers.”
- Assuming that what comes before is the cause of what comes after.
“I ate a snickers bar, then failed my test, therefore eating snickers bars makes me fail tests.”
- Jumping to conclusions based on what a person does not say.
- Selecting only the evidence that supports an argument.
- Slanting the question.
“Shouldn’t a woman be free to choose?”
Simplify these sentences into one of the four logical forms:
- Blessed are the poor in spirit.
- Whatever a man sows, he shall reap.
- He who is not with me is against me.
- A good tree cannot bring forth evil fruit.
- Some people are just lucky and some aren’t.
Find some of the arguments Victor Stenger makes against belief in God in this brief summary. Try to put them into one of the four logical forms below his article.
The New Atheism: Taking a Stand for Science and Reason by Victor Stenger
In The New Atheism, I review and expand upon the principles of New Atheism and answer many of its critics. I show how naturalism, the view that everything is matter and nothing more, is sufficient to explain everything we observe in the universe from the most distant galaxies to the inner workings of the brain that result in the phenomenon of mind. Nowhere is it necessary to introduce God or the supernatural to understand the world. I dispute the claim that science has nothing to say about God and argue that absence of evidence is evidence of absence when evidence should be there and is not.
“What Scares the New Atheists” by John Gray, theguardian.com
The resurgence of religion is a worldwide development. Russian Orthodoxy is stronger than it has been for over a century, while China is the scene of a reawakening of its indigenous faiths and of underground movements that could make it the largest Christian country in the world by the end of this century. Despite tentative shifts in opinion that have been hailed as evidence it is becoming less pious, the US remains massively and pervasively religious – it’s inconceivable that a professed unbeliever could become president, for example.
For secular thinkers, the continuing vitality of religion calls into question the belief that history underpins their values. To be sure, there is disagreement as to the nature of these values. But pretty well all secular thinkers now take for granted that modern societies must in the end converge on some version of liberalism. Never well founded, this assumption is today clearly unreasonable. So, not for the first time, secular thinkers look to science for a foundation for their values.
It’s probably just as well that the current generation of atheists seems to know so little of the longer history of atheist movements. When they assert that science can bridge fact and value, they overlook the many incompatible value-systems that have been defended in this way. There is no more reason to think science can determine human values today than there was at the time of Haeckel or Huxley. None of the divergent values that atheists have from time to time promoted has any essential connection with atheism, or with science. How could any increase in scientific knowledge validate values such as human equality and personal autonomy? The source of these values is not science. In fact, as the most widely-read atheist thinker of all time argued, these quintessential liberal values have their origins in monotheism.