2. Opinions, Beliefs, and Propositions
Beliefs are propositional – they are claims that are either
true or false
Opinions are beliefs and therefore are also propositional
• I believe It is immoral to eat other animals
=
• In my opinion it is immoral to eat other animals
=
• I’m claiming that it is immoral to eat other animals
3. P1. The decision of whether to live or die
primarily involves the patient’s values
Arguments about death and the meaning of life.
P2. Doctors are trained to respond to physical
suffering, not questions of existential
value.
An argument consists of two C. Doctors are therefore lack the expertise to
parts: one part (the premise or make such decisions (or validate the
premises) of which is intended decisions of their patients)
to provide a reason for
accepting the other part (the P1. Abortion is the intentional killing of
conclusion) innocent persons.
P2. Intentional killing of innocent
persons violates their right to life
C1. Abortion violates the right to life of
A good argument is one in innocent persons.
which the premises are
P4. Violating the right to life is morally
(1) true; and wrong & should be prohibited.
(2) relevant to the conclusion C2. Abortion is morally wrong & should
be prohibited
4. Is this an argument?
① People who are stupid here because I want todeserve any
⑤ Why am I here? I’m enough to smoke, don’t learn to
healthbetter.
think care services. Let them die!
① I’ve been going in God or condemn yourself to a life of
⑤ Either believe to McDonald’s for Big Macs for 30 years. I’m
meaninglessness!
happy with my purchase almost every time. Therefore, I will
probably be happy with my next McDonald’s purchase.
⑥ Our immigration policy is the result of a long history of
① George Washington never is not lie and neither should you
prejudice. Therefore, it told a just senseless, but
downright racist!
① We need a president that understands the economy, and so,
⑤ we should electcommercials extensive business experience
I never watch Romney. His and neither should you.
makes him want to be to be presidentto believe that you
You don’t well-suited brainwashed at a time when
nothing matters more than thereally don’t. And according
need something, which you economy. His success
leadingNew York Times, that’s into success leading our
to the a business will translate exactly what commercials
nation.do.
try to
5. Deductive & Inductive arguments
Deductive Proofs
• Aims to prove a conclusion P1. Voluntary Active Euthanasia
• Successful if the argument is reduces the pain and suffering
sound in the world
• Sound = the premises are
true and the argument is P2. Whatever reduces pain and
valid suffering in the world ought to
• An argument is valid if it’s be permitted.
impossible for its premises to
be true and its conclusion to C. Voluntary Active Euthanasia
be false. ought to be permitted
6. Deductive & Inductive arguments
Inductive Support
P1. We surveyed 10000
Californians about their views on • Supports, rather than proves,
gay marriage. a conclusion
• The degree of support it
P2. 64% of those surveyed were offers depends on how likely
in support of legalizing gay
marriage, 25% were against gay the premises make the
marriage, and 11% were conclusion
undecided.
• An argument’s strength
P3. State ballot measures require depends on how much
a majority vote to pass support it offers for the
conclusion. (more support =
C. A ballot measure legalizing gay stronger argument)
marriage will probably pass now
7. What are they arguing about?
• Diana: Abortion is immoral because it is
medically and psychologically harmful to the
mother.
• Maria: I disagree. It’s not having an
abortion when you need one that is
medically and psychologically harmful to the
mother.
8. What are they arguing about?
• Victor: I can’t believe they wont let us fish here anymore!
Our family has been fishing here for generations. That gives
us a right to our livelihood!
• Jacob: If the state allows everyone to keep fishing here – at
least for now – the fish population will be devastated and
the whole ecosystem around them will be affected. We
have a moral obligation to protect that ecosystem.
9. What are they arguing about?
• Sergei: If we make abortion illegal, more children will be
born whose parents are not able to adequately provide for
them.
• Wendy: Even if a child’s life is not a particularly good one,
it’s better than no life at all!
10. What are they arguing about?
• Jessica: Abortion is wrong because it is the
killing of an innocent person.
• Hector: It isn’t. A fetus is not a person!
It’s just a clump of cells. We have no good
reason to consider it a person.
11. What are they arguing about?
• Charlie: Restricting marriage to heterosexuals is unjust
discrimination.
• Briana: Marriage should only be allowed between one
man and one woman
13. ARE ANY OF THESE MORALLY WRONG?
GO AHEAD AND CONVINCE ME WITH A GOOD ARGUMENT!
14. Creating effective arguments – before you start
Step 1: Make sure you understand the
question/issue that the argument should
address.
Step 2: Determine a preliminary answer to that
question/issue. This will be your conclusion.
Step 3: Write out what you see as the
reasons/evidence, first for, then against your
conclusion
15. Creating effective arguments – standard form
Step 1: State your conclusion – what are you
trying to show?
Step 2: List your premises/evidence one by one
(P1, P2, P3, etc.) above the conclusion
Step 3: Examine your premises to see if they are
sufficient to support the conclusion.
Look for holes in your argument: missing
premises, unwarranted assumptions, biased
language, fallacious reasoning, etc.
Step 4: Make changes where helpful and return
to step 3 until your evidence provides strong
support for your conclusion
