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Thank you for inviting me to speak

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In designing a website one of your aims is

to stimulate action

This is almost certainly the main aim of

your employer

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There are all sorts of different actions you might want to

stimulate

• buying

• following

• liking

• clicking through

• recommending

• reviewing

often you’ll want to stimulate several actions

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Well action is something that philosophers

know a lot about

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Distinguish tripping over a carpet and

pretending to trip over a carpet – which is

an action and why?

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Pretending to trip over a carpet is an

action because:

• it is chosen

• it is performed intentionally

• it is performed for reasons

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When human beings act they make

choices

When human beings make choices they do

so for reasons

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If we want to understand action,

therefore, and how to stimulate it, it

is necessary to understand reason

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To be rational is to be such that some of your behaviour is reason-driven

Most rational things are such that most of their behaviour is non-rational

To be rational is to be capable of being irrational

Non-rational things are neither rational nor irrational

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What is a reason?

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A reason-driven behaviour (an

action)…

… is a behaviour caused by a

combination of desires and beliefs

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Desires and beliefs are both mental

states…

… but they differ from each other

quite radically

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Desires and beliefs play different

roles in the production of action

Desires and beliefs have a different

relation to reason

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Desires motivate action

Beliefs guide action towards its goal

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It is not possible to reason anyone

into a desire

It is only beliefs that we can be

reasoned into

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I understand that ‘UX’ stands for ‘User

Experience’…

… and that it was born because your

main aim in designing a website…

… is to provide the user with

whatever he or she wants

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Unless you are offering something the

user wants you’ll never get anywhere

But the user’s wants – desires – are only

half the picture

The user’s beliefs about how to fulfil his

desires are the other half

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In fact given that there is little you can do

about your users’ desires…

… your main aim (I respectfully

submit!)…

… should be to give your user the

belief that…

…by using your website he can fulfil

(some of) his desires 19

So let’s consider the nature of beliefs

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• all beliefs have contents

• the contents of beliefs are constituted of

concepts

• every belief is related to every other belief

• beliefs admit truth and falsehood

• beliefs are expressed in sentences

• human beings care (to some extent) about

the truth of their beliefs21

Relations between beliefs can be:

• rational

• irrational

• non-rational

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A rational relation between beliefs:

Belief one: Marianne always wears jeans on a Friday

Belief two: It is Friday

Belief three: Marianne is wearing jeans

The rational relation between these beliefs is entailment

If beliefs one and two are true, belief three must be true

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These beliefs amount to a deductive

argument

Premise one: Marianne always

wears jeans on a Friday

Premise two: It is Friday

Conclusion: Marianne is wearing

jeans

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All arguments are relations between beliefs such that…

…one belief is the conclusion…

… and the other beliefs are its premises …

…(the reasons given for the conclusion)

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There are two types of argument:

• deductive arguments

• inductive arguments

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Deductive arguments give us certainty

(conditionally on the truth of the

premises)

Valid deductive arguments are conclusive

Valid deductive arguments can be

evaluated a priori

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P1: All doodahs are whotsits

P2: All whotsits are green

C: This doodah is……

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Irrational relations between beliefs:

Premise one: Marianne always

wears jeans on a

Friday

Premise two: Marianne is wearing

jeans

Conclusion: It is Friday

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Non-rational relations between

beliefs:

Premise one: I want my spouse

to be faithful

Conclusion: My spouse IS

faithful

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Inductive reasoning takes us from observations of the past to predictions about the future:

P1: I have seen the sun rise every day in the

history of the universe

C: I expect the sun to rise tomorrow

Inductive reasoning is hugely important to human beings

Inductive argument is central to science

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Huge philosophical controversy: is

induction rational?

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The Scottish Philosopher David

Hume noted that…

… every inductive argument

contains a hidden premise…

… that nature is uniform (the

future will be like the past)

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This premise cannot be justified

• deductively (it generates no

contradiction to believe that nature is

not uniform)

• inductively (we’d be arguing in a

circle)

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Hume argued that induction is non-

rational

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But it is clear that we can distinguish between good inductive arguments and badinductive arguments:

Women who drink this brand of vodka are beautiful, rich and attract the most handsome men

If I drink this vodka I will become beautiful, rich and start attracting the most handsome men

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Philosophers live in hope of finding a

systematic way to distinguish

between good and bad inductions

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Summary:

• actions are reason-driven

• for an action to be reason-driven is for it to be:

• motivated by desire

• guided by belief

• it is not possible to argue anyone into a desire

• if you want to satisfy users’ desires it is their beliefs you need to address

• users’ beliefs can be changed and brought into being rationally, irrationally or non-rationally

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If you want to inspire trust it is

always better to change someone’s

beliefs by rational means!

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