1. Legal Argumentation 1 Henry Prakken March 21, 2013

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 Premise 1Premise n ….. therefore

8. 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 DNA found at crime scene Witness W saw S at crime scene P E is expert on PE 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

9. 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

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

11. 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

12. 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

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

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

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

17. Manslaughter IntentKilled Drove 180 where max 80 Police radar Computer log file Victim died Report coroner Caused by collision Collision Report coroner 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

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

19. Manslaughter IntentKilled Drove 180 where max 80 Police radar Computer log file Victim died Report coroner Caused by collision Collision Report coroner 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

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)