Legal Argumentation 1

1. Legal Argumentation 1 Henry Prakken February 23, 2012

2. What is argumentation? • Giving reasons to support or criticise claims that are open to doubt • logic + dialectic • Often to persuade someone else • rhetoric Proponent: Regarding downloading Mp3s as copying for private use is wrong Respondent: Why? Proponent: Because it makes normal commercial exploitation of music impossible Respondent: Why? Proponent: Because it’s so easy to copy, upload and download MP3s

3. What is argumentation? • Giving reasons to support or criticise claims that are open to doubt • logic + dialectic • Often to persuade someone else • rhetoric Proponent: Regarding downloading Mp3s as copying for private use is wrong Respondent: Why? Proponent: Because it makes normal commercial exploitation of music impossible Respondent: Why? Proponent: Because it’s so easy to copy, upload and download MP3s Respondent: But there are quite profitable ways to sell Mp3s online Proponent: Really? Respondent: Look at iTunes

4. Legal contexts of argumentation • In court • In legal consultancy • In scholarly debate • In public debate • …

5. 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

6. The structure of legal arguments

7. The structure of arguments:basic elements • (Basic) arguments have: • Premises (grounds) • A conclusion • A reasoning step from the premises to the conclusion Conclusion therefore ….. Premise 1 Premise n

8. P E is expert on P E says that P The offer was written The offer was made in an email The offer was made in a letter Three types of support Cumulative (all premises needed for conclusion) Alternative (one premise suffices for conclusion) S was at crime scene Aggregate (the more support the better) S’s DNA matches DNA found at crime scene Witness W saw S at crime scene

9. Alternative support is in fact alternative arguments The offer was written The offer was written The offer was made in a letter The offer was made in an email

10. Implicit premises The offer was written The offer was made in a letter

11. Implicit premises The offer was written The offer was made in a letter If the offer was made in a letter or email then it was written

12. Implicit premises The offer was written The offer was made in an email If the offer was made in a letter or email then it was written

13. Legal reasoning: three stages • Determining the facts of the case • Classifying the facts under the conditions of a legal rule • Applying the rule

14. Manslaughter Intent Killed Recklessness Collision Victim died Caused by collision Drove 180 where max 80 Police radar Witness: “collision” Police report: “collision” Report coroner Report coroner Computer log file

15. Manslaughter Intent Killed Art. 287 CC Recklessness Collision Victim died Caused by collision Drove 180 where max 80 Police radar Witness: “collision” Police report: “collision” Report coroner Report coroner Computer log file

16. Manslaughter Intent Killed Art. 287 CC Causing a collision in consequence of which someone dies is killing Recklessness Collision Victim died Caused by collision Drove 180 where max 80 Police radar Witness: “collision” Police report: “collision” Report coroner Report coroner Computer log file

17. Manslaughter Driving 180 where maximum speed is 80 is consciously taking the risk of a collision, which is Recklessness Intent Killed Art. 287 CC Recklessness Collision Victim died Caused by collision Drove 180 where max 80 Police radar Witness: “collision” Police report: “collision” Report coroner Report coroner Computer log file

18. Manslaughter Intent Killed Art. 287 CC Recklessness Police radars are a reliable source of information on speed Collision Victim died Caused by collision Drove 180 where max 80 Police radar Witness: “collision” Police report: “collision” Report coroner Report coroner Computer log file

19. Manslaughter Intent Killed Art. 287 CC Recklessness Collision Victim died Caused by collision Drove 180 where max 80 This type of computer log file is a reliable indicator of what the radar has measured Police radar Witness: “collision” Police report: “collision” Report coroner Report coroner Computer log file

20. 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

21. Identifying missing premises: normative, not psychological • Muslim extremists should be denied free speech since they preach hatred

22. 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?

23. 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.

24. 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.

25. Summary • Arguments can have different combinations of premises • Arguments can be constructed step by step • These steps often leave rules or generalisations implicit

26. Next week • Arguments and counterarguments • Argument schemes (1)