# Some Slides on Topics from Previous Classes

## Some more problems in Von Wright

### Indifference

If an act and its negation are both permitted, the act is called (morally) indifferent.

#### Problem

Missing fine-grained distinctions. Optionality vs. Indifference.

### Commitments / Conditional Norms

See criticism by Chisholm.

## Modelling Chisholm: the logical challenge

see other slides.

## Deontic vs. Factual Detachment Principles

Factual Detachment
If
1. $$a$$ and
2. $$a$$ commits you to $$b$$.

Then $$Ob$$.

Deontic Detachment
If
1. $$Oa$$ and
2. $$a$$ commits you to $$b$$

then $$Ob$$.

Generalised Deontic Detachment
If
1. $$a$$ commits you to $$b$$, and
2. $$b$$ commits you to $$c$$.

then $$a$$ commits you to $$c$$.

## CTD-cases

Entered on [2015-05-21 Thu 07:47]

• strong (Forrester) vs. weak (no conflict btw. specific obligation and general one)

### Examples

#### OO

##### Reykjavik-example
• You ought not to tell Reagan nor Gorbatjov.
• If you tell Reagan you ought to tell Gorbatjov.
• If you tell Gorbatjov you ought to tell Reagan.
##### apologise
• You ought not to have a reason to apologise (e.g., to your neighbor, etc.).
• If you have no reason to apologise you ought not to apologise.
• If you have a reason to apologise, you should apologise.
##### rules of a game
• Every player ought to pay X every round.
• If some player forgot to pay X some round, the next round the other player ought not to pay either.
##### pilot
• If you get the OK from the tower, you ought to not wait for another signal and take off at 10pm.
• If you get the OK from the tower but you don't take off at 10pm, you ought to wait for another signal.
##### uni-life
• You ought not to use your mobile phone during the course.
• However, if you do, use it in order to enlarge your understanding of things taught in the course.
##### uni-life 2: your parents may tell you:
• You should be present at your course.
• If you're not, then you should at least study in the library.
##### cheating
• You ought not to cheat.
• However, if you cheat, don't get caught cheating.
##### stealing
• You ought not to steal.
• If you steal, steal from the rich.

#### OP

##### authorisations (Chisholm style)
• You ought to do your homework.
• If you do your homework you are permitted to hang out with your friends.
• If you do not do your homework, you ought to not hang out with your friends.

## A look back at Prior's Paradox (the good Samaritan)

• adverbial who has been robbed

Problem: helping the neighbor who has been robbed implies that the neighbor has been robbed.

Inheritance principle
If a entails b then Oa entails Ob.
(no term)
Intuitive but leads to absurdity: The neighbor ought to be robbed.

## Forrester's response

It's just a scope-problem:

• Help neighbor: h
• Neighbor has been robbed: r
• Phrase it like: $$O(h) \wedge r$$ instead of $$O(h \wedge r)$$
• Problem: does it really represent the informal phrasing?

• Help(Smith who has been robbed) is logically equivalent to Help(Smith) and Smith has been robbed.
• If a and b are logically equivalent then Oa and Ob are as well.
• But then: Ought(Help(Smith who has been robbed)) is equivalent to Ought(Help(Smith) and Smith has been robbed).
• If we think there is nothing wrong with the first formulation we have to accept the second one. With the Inheritance principle we run into the old problems.

## What about a conditional equivalence principle?

Conditional Equivalence principles
Given
1. If $$a$$ then $$Ob$$.
2. $$a \vdash b \equiv c$$

Then: If $$a$$ then $$Oc$$.

Think about it and evaluate it as a principle for

• action types
• state of affairs.

## Example

Action types:

• You should not kill.
• If you kill, inflict as little pain as possible.
• If you kill, inflicting as little pain as possible is equivalent to killing gently.
• Hence, if you kill, kill gently.

## More trouble with inheritance

Question: $$O(a_1 \wedge \ldots \wedge a_n)$$ implies $$O(a_i)$$?

• birthday cake example

## Sing and Dance!

Question: does the following principle hold (Cautious Transitivity)

• If
1. $$a$$ commits you to $$b$$
2. $$a$$ and $$b$$ commits you to $$c$$
• then $$a$$ commits you to $$c$$?

Parent and Van der Torre argue: NOPE!

• If
1. $$a$$ commits you to $$b$$
2. $$a$$ and $$b$$ commits you to $$c$$
• then $$a$$ commits you to $$b \wedge c$$?

This shows again, that there are cases which violate inheritance.

## How to distinguish cases in which inheritance holds?

1. $$O(a \wedge b)$$ and
2. If $$\neg b$$ you ought to $$a$$.
then $$Oa$$.