Legal Argumentation 1

Henry Prakken

February 23, 2012

What is argumentation? Giving reasons to support or

criticise claims that are open to doubt logic + dialectic

Often to persuade someone else rhetoricProponent: Regarding downloading Mp3s as copying for private use is wrong

Respondent: Why?Proponent: Because it makes normal commercial exploitation of music impossibleRespondent: Why?Proponent: Because it’s so easy to copy, upload and download MP3s

What is argumentation? Giving reasons to support or

criticise claims that are open to doubt logic + dialectic

Often to persuade someone else rhetoricProponent: Regarding downloading Mp3s as copying for private use is wrong

Respondent: Why?Proponent: Because it makes normal commercial exploitation of music impossibleRespondent: Why?Proponent: Because it’s so easy to copy, upload and download MP3sRespondent: But there are quite profitable ways to sell Mp3s onlineProponent: Really?Respondent: Look at iTunes

Legal contexts of argumentation

In court In legal consultancy In scholarly debate In public debate …

Overview of course Week 1:

Basic structure of arguments Combinations of premises implicit premises Multi-steps arguments

Week 2: Arguments and counterarguments Argument schemes (1)

Week 3: Argument schemes (2) Evaluating arguments Discussion of homework

The structure of legal arguments

The structure of arguments:basic elements

(Basic) arguments have: Premises (grounds) A conclusion A reasoning step from the premises to

the conclusion

Conclusion

Premise 1 Premise n…..

therefore

Three types of support

Cumulative (all premises needed for conclusion)

Alternative (one premise suffices for conclusion)

S was at crime scene

S’s DNA matches DNAfound at crime scene

Witness W saw S at crime scene

P

E is expert on P E says that P

Aggregate (the more support the better)

The offer was written

The offer was made in a letter

The offer was made in an email

Alternative support is in fact alternative arguments

The offer was written

The offer was made

in a letter The offer was made

in an email

The offer was written

Implicit premises

The offer was made

in a letter

The offer was written

Implicit premises

The offer was made

in a letter

The offer was written

If the offer was made in a letter or email then it was

written

Implicit premises

The offer was made in an email

The offer was written

If the offer was made in a letter or email then it was

written

Legal reasoning: three stages

Determining the facts of the case

Classifying the facts under the conditions of a legal rule

Applying the rule

Manslaughter

Intent Killed

Drove 180 where max 80

Police radar

Computerlog file

Victim died

Report coroner

Caused bycollision

Collision

Reportcoroner

Witness:“collision”

Police report:“collision”

Recklessness

Manslaughter

Intent Killed

Drove 180 where max 80

Police radar

Computerlog file

Victim died

Report coroner

Caused bycollision

Collision

Reportcoroner

Witness:“collision”

Police report:“collision”

Recklessness

Art. 287 CC

Manslaughter

Intent Killed

Drove 180 where max 80

Police radar

Computerlog file

Victim died

Report coroner

Caused bycollision

Collision

Reportcoroner

Witness:“collision”

Police report:“collision”

Recklessness

Art. 287 CC

Causing a collision in consequence of

which someone dies is killing

Manslaughter

Intent Killed

Drove 180 where max 80

Police radar

Computerlog file

Victim died

Report coroner

Caused bycollision

Collision

Reportcoroner

Witness:“collision”

Police report:“collision”

Recklessness

Art. 287 CC

Driving 180 where maximum speed is 80 is consciously

taking the risk of a collision, which is

Recklessness

Manslaughter

Intent Killed

Drove 180 where max 80

Police radar

Computerlog file

Victim died

Report coroner

Caused bycollision

Collision

Reportcoroner

Witness:“collision”

Police report:“collision”

Recklessness

Art. 287 CC

Police radars are a reliable source of

information on speed

Manslaughter

Intent Killed

Drove 180 where max 80

Police radar

Computerlog file

Victim died

Report coroner

Caused bycollision

Collision

Reportcoroner

Witness:“collision”

Police report:“collision”

Recklessness

Art. 287 CC

This type of computer log file is a reliable indicator of what the radar

has measured

Two important features of arguments

Arguments can be constructed step by step

These steps often leave rules or generalisations implicit When testing arguments, they must be

made explicit to reveal sources of doubt

They can be unfounded They can have exceptions

Identifying missing premises: normative, not psychological

Muslim extremists should be denied free speech since they preach hatred

Identifying missing premises: normative, not psychological

Muslim extremists should be denied free speech since they preach hatred

So you think that anyone who preaches hatred should be denied free speech?

Identifying missing premises: normative, not psychological

Muslim extremists should be denied free speech since they preach hatred

So you think that anyone who preaches hatred should be denied free speech?

Yes.

Identifying missing premises: normative, not psychological

Muslim extremists should be denied free speech since they preach hatred

So you think that anyone who preaches hatred should be denied free speech?

Yes. But Geert Wilders also preaches hatred,

so you should deny him free speech as well.

Summary Arguments can have different

combinations of premises Arguments can be constructed

step by step These steps often leave rules or

generalisations implicit

Next week Arguments and counterarguments Argument schemes (1)