some methods and interests. argument argument is at the heart of philosophy argument is at the heart...

Some Methods and Some Methods and InterestsInterests

ArgumentArgument

Argument is at the heart of philosophyArgument is at the heart of philosophy It is the only method for getting resultsIt is the only method for getting results The The naturenature of the method is also of interest of the method is also of interest

We seek abstract knowledge of We seek abstract knowledge of argumentsarguments Allows knowledge of particular argumentsAllows knowledge of particular arguments Is studied in Is studied in Logic Logic ((Formal and InformalFormal and Informal))

ArgumentArgument

Let’s look at how we talk about Let’s look at how we talk about argumentsarguments This will make future discussions less This will make future discussions less

scary as the scary as the way way we discuss things will we discuss things will be familiar to yoube familiar to you

And will leave you able to follow the And will leave you able to follow the content content of the discussion without of the discussion without having to struggle with the having to struggle with the formform

ArgumentArgument

Deductive argumentsDeductive arguments

Socrates is a manSocrates is a man

All men are mortalAll men are mortal

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Socrates is mortalSocrates is mortal

In a In a valid valid deductive argument, if the deductive argument, if the premisses are true then the conclusion premisses are true then the conclusion mustmust be true be true

ArgumentArgument

Inductive argumentsInductive arguments

Swan number 1 is whiteSwan number 1 is white

Swan number 2 is whiteSwan number 2 is white

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All swans are whiteAll swans are white

In a In a strong strong inductive argument, if the inductive argument, if the premisses are true it makes the premisses are true it makes the conclusion conclusion probably probably truetrue

Logic MattersLogic Matters

The argument in the The argument in the EuthyphroEuthyphro was was basically this:basically this:1. Socrates gets from Euthyphro a definition of

‘piety:’Piety is what the gods love and impiety

what the gods hate.

2. Socrates then derives certain consequences of this definition. Specifically:

the same things are both pious and impious

3. Finally deriving the conclusion that:Piety is not what the gods love nor impiety

what they hate.


I claim this involves an argument of the I claim this involves an argument of the formform

If A then BIf A then B

Not BNot B

Not ANot A

This form is called This form is called modus tollens modus tollens Let’s look at this formLet’s look at this form


Here’s an exampleHere’s an example


Not BNot B

Not ANot A



If it has rained then the grass is If it has rained then the grass is wetwet

Not BNot B

Not ANot A



If it has rained then the grass is If it has rained then the grass is wetwet

The grass is not wetThe grass is not wet

Not ANot A



If it has rained then the grass is wetIf it has rained then the grass is wet

The grass is not wetThe grass is not wet

It has not rainedIt has not rained

This is a This is a validvalid argumentargument If the reasons are true the conclusion If the reasons are true the conclusion mustmust

be truebe true


Here’s another exampleHere’s another example


Not BNot B

Not ANot A



If Socrates is a man then he is If Socrates is a man then he is mortalmortal

Not BNot B

Not ANot A



If Socrates is a man then he is If Socrates is a man then he is mortalmortal

Socrates is not mortalSocrates is not mortal

Not ANot A



If Socrates is a man then he is mortalIf Socrates is a man then he is mortal

Socrates is not mortalSocrates is not mortal

Socrates is not a manSocrates is not a man

This is This is still still a a validvalid argumentargument IfIf the reasons are true the conclusion must the reasons are true the conclusion must

be truebe true


AnyAny modus tollensmodus tollens argument is a argument is a valid argumentvalid argument It is a It is a valid formvalid form

Why do we say the Why do we say the Euthyphro Euthyphro argument was argument was modus tollensmodus tollens? ? Because it looks like this: Because it looks like this:


If piety is what is loved by the gods If piety is what is loved by the gods then the same things are both pious then the same things are both pious and impious.and impious.

The same things are The same things are not not both pious both pious and impiousand impious


If piety is what is loved by the gods If piety is what is loved by the gods then the same things are both pious then the same things are both pious and impious.and impious.

The same things are The same things are not not both pious both pious and impiousand impious

Piety is Piety is notnot what is loved by the gods what is loved by the gods


If piety is what is loved by the gods then the If piety is what is loved by the gods then the same things are both pious and impious.same things are both pious and impious.

The same things are The same things are not not both pious and both pious and impiousimpious


We know the second premise is trueWe know the second premise is true Because we know any contradiction must be Because we know any contradiction must be

falsefalse





We know the first premise is trueWe know the first premise is true Because we agreed to each step of the argument Because we agreed to each step of the argument

that derived the ‘then’ part from the ‘if’ partthat derived the ‘then’ part from the ‘if’ part





We know the conclusion is trueWe know the conclusion is true Because we see that the argument is Because we see that the argument is modus modus

tollens tollens and we know it has true premisesand we know it has true premises

Science MattersScience Matters

This kind of argument has a role in This kind of argument has a role in ScienceScience It is part of the method that scientists use It is part of the method that scientists use

to seek answers to such questions as to seek answers to such questions as Why do needles point north?Why do needles point north? Why do sticks bend going into water?Why do sticks bend going into water? Why does water boil when heated?Why does water boil when heated?

Science has earned great respect as a Science has earned great respect as a way of getting at the truth of thingsway of getting at the truth of things So its methods should be valuedSo its methods should be valued


How do scientists seek answers for How do scientists seek answers for questions about the world?questions about the world? They apply the They apply the Hypothetico-Deductive Hypothetico-Deductive

MethodMethod

1. Form a hypothesis2. Deduce testable consequences from the

hypothesis3. Test for these consequences4. Confirm or disconfirm the hypothesis


Example: Why do we sometimes see the Example: Why do we sometimes see the same collections of fossilized plants and same collections of fossilized plants and animals on opposite sides of oceans?animals on opposite sides of oceans?

1. Form a hypothesis2. Deduce testable consequences from the




1. There were land bridges across the oceans2. Deduce testable consequences from the




1. There were land bridges across the oceans2. There would be remains of those bridges3. Test for these consequences4. Confirm or disconfirm the hypothesis



1. There were land bridges across the oceans2. There would be remains of those bridges3. There is no evidence of these bridges4. Confirm or disconfirm the hypothesis



1. There were land bridges across the oceans2. There would be remains of those bridges3. There is no evidence of these bridges4. Land bridges didn’t cross the oceans



1. Form another hypothesis2. Deduce testable consequences from the




1. The continents were previously joined but split up

2. Deduce testable consequences from the hypothesis

3. Test for these consequences4. Confirm or disconfirm the hypothesis




2. The continents are moving3. Test for these consequences4. Confirm or disconfirm the hypothesis




2. The continents are moving3. Measurements show that they are moving4. Confirm or disconfirm the hypothesis




2. The continents are moving3. Measurements show that they are moving4. The continents could have split up


The similarity of the Hypothetico-The similarity of the Hypothetico-Deductive Method and the method of Deductive Method and the method of elenchuselenchus is clear is clear The method is not what distinguishes The method is not what distinguishes

PhilosophyPhilosophy Philosophers see themselves as Philosophers see themselves as

engaged in the same pursuit of truth engaged in the same pursuit of truth as the scientistsas the scientists


Philosophy is prior to science in that Philosophy is prior to science in that pursuitpursuit Many scientific topics were originally Many scientific topics were originally

philosophicalphilosophical physics, astronomy, cosmology, chemistry, biology, …

When do they become sciences rather than philosophies?

When they begin to ask questions whose answers can be found by inspecting the world

Philosophy is needed to discover which parts of a topic asks questions that can be answered in that way

Conceptual clarityConceptual clarity

So what does philosophy do if it So what does philosophy do if it doesn’t ask questions that the world doesn’t ask questions that the world can answer?can answer? It clarifies concepts and allows other It clarifies concepts and allows other

methods of enquiry to go forward. methods of enquiry to go forward. Science depends on this.Science depends on this.


Example 1. Example 1. The Greeks couldn’t see how motion was The Greeks couldn’t see how motion was

possiblepossible For something to move everything at the For something to move everything at the

destination must movedestination must move For everything at the destination to move there For everything at the destination to move there

must be somewhere to go where there is nothingmust be somewhere to go where there is nothing But everywhere there is something But everywhere there is something So motion is impossibleSo motion is impossible

We think this argument is nonsensical. Why We think this argument is nonsensical. Why did the Greeks have problems?did the Greeks have problems?


Example 1. Example 1. The Greeks did not distinguish space The Greeks did not distinguish space

and matterand matter We think of matter as We think of matter as occupying occupying spacespace They thought of matter as They thought of matter as constituting constituting

spacespace They conceived of space and matter as They conceived of space and matter as

being like a brick wallbeing like a brick wall Where there was no matter there was not Where there was no matter there was not

empty space: there was just nothingempty space: there was just nothing


Example 2. Example 2. Early scientists couldn’t ‘understand’ Early scientists couldn’t ‘understand’

Newton’s force of GravityNewton’s force of Gravity For one body to cause a change in another For one body to cause a change in another

there must be contactthere must be contact The moon and the earth are not in contact The moon and the earth are not in contact

so neither so neither could affect the othercould affect the other So Gravity is impossibleSo Gravity is impossible


Example 3. Example 3. We don’t ‘understand’ the nature of We don’t ‘understand’ the nature of

mattermatter Sometimes it behaves like particlesSometimes it behaves like particles Other times it behaves like wavesOther times it behaves like waves

It isn’t just ambiguityIt isn’t just ambiguity Matter seems to be aware of the situation it Matter seems to be aware of the situation it

is in and behaves appropriatelyis in and behaves appropriately That is absurd, and yet:That is absurd, and yet:


There’s a more basic reason to value There’s a more basic reason to value clear and well-formed conceptsclear and well-formed concepts

We are We are intentionalintentional actors actors We act rationally on our beliefs in order to We act rationally on our beliefs in order to

satisfy our desiressatisfy our desires To apply reason to our beliefs and desires To apply reason to our beliefs and desires

these need to be conceptsthese need to be concepts To be To be successfulsuccessful intentional actors our intentional actors our

concepts need to be clear and well-concepts need to be clear and well-formedformed

some methods and interests. argument argument is at the heart of philosophy argument is at the heart...

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