Truth and Reasons
Define truth relativism in one sentence.
Whatever you believe is true-for-you.
Define an argument in a few words.
A line of reasoning
What criterion of success is shared by arguments of all types?
Their premises must be true.
What does it take for a deductive argument to be sound?
True Premises + Logical Validity
Is this argument logically valid?
All swans are birds.
All birds are beautiful.
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Therefore, all swans are beautiful.
Yep! Logically valid
When a piece of evidence supports a statement P, the piece of evidence ...
(A) Justifies belief in P
(B) Is a reason for holding the belief
(C) Both of the above.
C
What are the two essential components of an argument?
Premises and conclusion.
True or False:
If an argument is logically valid, then its premises must be true.
False.
True.
Is this argument logically valid?
Some ravens can fly.
Some ravens are black.
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Therefore, all ravens are black and can fly.
Not valid.
(A) False
(B) Unreasonable
(C) Both of the above
B
An argument might be broken down into smaller inferences/lines of reasoning that serve as stepping-stones. The conclusions of those inferences are called...
Sub-conclusions / Intermediate conclusions
True or False:
All deductive arguments are logically valid.
False! They strive to be logically valid, but some fail.
Why is it so bad to affirm the premises of a valid argument but deny its conclusion at the same time?
Because you would be implicitly accepting a contradiction!
Is the argument sound?
All ravens we've observed are black.
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Therefore, all ravens are black.
Unsound, because it's logically invalid.
What common-sensical distinction does truth relativism abandon?
The distinction between what one believes and what is true.
Even if a line of reasoning is logically flawless, it's still possible that one may not believe its conclusion rationally. Why?
Because one's belief in the premises may be unreasonable.
Name a type of inductive reasoning.
- Inference to the Best Explanation
- Enumerative Induction
True or False: If an argument has all true premises and its conclusion is also true, does it mean it is sound?
Nope. Because it may fail to be logically valid.
Why is this argument unsound?
Either the Earth is flat or 1 + 1 = 3.
The Earth is not flat.
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Therefore, 1 + 1 = 3.
What are Plato's two arguments against truth relativism?
- By its own logic, the view isn't true for those who disbelieve it.
- It implausibly predicts that we have no reason to listen to experts.
Explain the distinction between personal justification and interpersonal justification.
Personal justification: making one's belief rational
Interpersonal justification: Persuading others to hold a belief rationally
Define "a logically valid argument" in terms of logical impossibility.
It is logically impossible for its premises to be all true but its conclusion to be not true.
If an argument is logically invalid, it necessarily means it is an unsuccessful argument.
Nope! Because the argument could be intended to be inductive.
Is the following argument logically valid? (Focus on the definition)
Ian is happy. Therefore, Ian is happy.
Logically valid.
Though it's circular and, therefore, a bad argument.