Presentation to publication In: E. Schweighofer, F. Kummer, W. Hötzendorfer, C. Sorge (eds.) Trends and Communities of Legal Informatics. Proceedings of the 20th International Legal Informatics Symposium IRIS 2017, 23–25 February 2017, Salzburg, pp. 349–358. OCG, Vienna. ISBN 978-3-903035-15-7. Also in online journal Jusletter IT, Die Zeitschrift für IT und Recht, 23 February 2017, ISSN 1664-848X, Editions Weblaw, http://jusletter-it.weblaw.ch/issues/2017/IRIS.html. (Peer reviewed – Jury LexisNexis Best Paper Award IRIS2017). ABSTRACT. Hajime Yoshino’s Logical Jurisprudence (LJ) is an important concept in legal infor-matics. Yoshino aims for a logic-based systematization in the legal domain. He focuses on legal reasoning and systematization. Inevitably, embracing law as a whole brings us to Hans Kelsen’s Pure Theory of Law. In sum, three issues are important in LJ: logic, Kelsen and legal informatics. In this paper we aim to visualize the architecture of LJ. We suggest expanding this with legal ontologies and words. The granularity of word-phrase-sentence-text is about different methods which apply to different units.

1. Visualization
of Hajime Yoshino’s
Logical Jurisprudence
IRIS 2017, 23-25.02.2017, Salzburg
Vytautas Čyras
Vilnius University
Lithuania
Friedrich Lachmayer
Vienna

2. Based on:
• Friedrich Lachmayer’s slides
- 2007, presentation at KEIO University, Tokyo
- 24.11.2016, Austrian Parliament
- in connection with Legal Framing 2016
• Hajime Yoshino’s slides and papers
- IRIS 2007, 22.2.2007, Salzburg
- 11th ICAIL 2007, Stanford
- 13th ICAIL 2011
- …
- Legal Framing, 23.11.2016 , Vienna
2

3. Scientific Audience,
Applications
Legal Science,
Jurisprudence
Introduction to the Visualisation-Schemata
3
State Law
Stage of Rights and Duties

4. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Law
Deduction
Natural Law Principles
Pufendorf
4

5. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Constitution
Basic Norm
Kelsen
Legal Hierarchy
indiv. Judgements
5

6. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Scientific
Logical Sentences
Logic
Yoshino
6

7. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Introduction
Computer
Expert Systems
Logic
Yoshino
Scientific
Logical Sentences
Applications
Applications
7

8. Logical
Jurisprudence
LJ
8

9. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
whole
Legal System
Logical
Jurisprudence
try to analyze and explain
9

10. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Legal System
LJ tries to analyse and construct its scientific theory of law
with minimum simple frames like classical physics did.
Logical
Jurisprudence

11. Three Primitives
LJ
LJ tries to analyse and explain
the whole legal system
using minimum elements
11

12. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Three Primitives:
S Sentence
V Validity
Inference Rule
Modus Ponens
12
1
2
3

13. (1) “sentence”
• LJ considers that norm as a meaning does not exist.
• LJ starts from sentences.
(2) “validity” of sentence
• Legal validity as truth
“is_valid(sentence1, goal1, time1)”
(3) “inference rule”
• Modus ponens: P, P ⇒ Q |- Q
Starts form three primitives:
LJ
13
Thought
Symbol
(representation)
Referent
(thing)
Actor?

14. Three Types
of
Legal Sentences
LJ
14

15. LRS
Legal Rule Sentence
describes
Legal Rules
15

16. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
LS – Legal Sentence
LJ starts from
Legal Sentences
not Legal Norms

17. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
LN – Legal Norm LS – Legal Sentence
LJ deals with Legal Sentences but not Legal Norms
(as meanings which do not exist in reality)

18. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
LR Legal Rule
LRS
Legal Rule-Sentence
Legal rule sentences and fact sentences

19. LFS
Legal Fact Sentence
describes
Legal Facts
19

20. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
LF Legal Fact
LFS
Legal Fact Sentence
20

21. LOS
Legal Object Sentence
describes Legal Objects,
especially Obligations
21

22. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Legal
Role
LO Legal Object
Obligation
Legal
Role
LOS
Legal Object Sentence
22

23. LMS
Legal Meta Sentence
describes about the
validity of legal sentences
23

24. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
LS
Legal Sentence
validitydescribes
LMS
Legal Meta Sentence
24

25. ELS
Elementary Legal Sentence
is the smallest unit of legal sentences.
“One must drive a car under 100 km /hour on a highway”
25

26. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
ELS
smallest unit
of Legal Sentences
26

27. Structure
of Connection of
Legal Sentences
LS LS
LS
(1) Connective “And” (&)
(2) Connection in a Complex Sentence
(3) Connection of LOS with LMS
(4) Connection of LMS with LMS
27

28. “And” structure
of the connection
of LS
Structure of Connection of LS: (1)
LS LS
LS
28

29. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
a group of LS
which has an unique name
LS LSAND
29

30. Connection
in
Complex Sentence
Structure of Connection of LS: (2)
LS LS
LS
30

31. CLS
Complex Legal Sentence
includes Legal Sentences
31

32. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
CLS
a group of LS
which has an unique name
LS LS
LS
32

33. Connection of
LOS with LMS
Structure of Connection of LS: (3)
LS LS
LS
33

34. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Legal
Rules
Legal
Facts
34

35. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
LRS
LFS
Legal
Rules
Legal
Facts
represented by
35

36. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
IR Inference Rule
Modus Ponens
LRS
prooved
validity
LFS
Legal
Rules
Legal
Facts
LOSrepresented by
36

37. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Legal Object
Legal State of Affair
IR Inference Rule
Modus Ponens
LRS
proved
validity
LFS
Legal
Rules
Legal
Facts
LOSrepresented by
37

38. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Legal Object
Legal State of Affair
IR Inference Rule
Modus Ponens
LRS
proved
validity
LFS
Legal
Rules
Legal
Facts
LOSrepresented by
Computer
Expert Systems
38
Inference

39. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
Legal Object
Legal State of Affair
IR Inference Rule
Modus Ponens
LRS
proved
validity
LFS
Legal
Rules
Legal
Facts
LOSrepresented by
• The legal sentence itself is merely
an array of symbols.
• The meaning of a legal sentence
only becomes visible when people
use it. In other words, the legal
inference activates LSs as living
legal norms.
• LJ considers the reasoning of the
application of law as the process of
developing legal sentences.
• The legal reasoning consist of
reasoning of justification and
reasoning of creation which are
related to each other.
Inference

40. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties

41. Connection
of
LMS with LMS
Structure of Connection of LS: (4)
LS LS
LS
41

42. FLMRS
Fundamental Legal
Meta Rule Sentence
42

43. Fundamental legal meta
rule sentence – FLMRS
A legal sentence S is valid for a goal G at the time T 
S becomes valid for G at time T1 before T &
not(S is terminated for G after T1 and before T).
This is a FLMRS implicitly taken granted for
all regulations.
All other (positive) LRS regulate the fulfillment of the
first requirement (S becomes valid) or the second
requirement (S is terminated) of this rule.
43

44. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
all Regulations
FLMRS Fundamental
Legal Metarule Sentence
MRS
Legal Metarule Sentence
LRS
Legal Rule Sentence
44

45. BLRS
Basic Legal Rule Sentence
 Validity of the final highest LMS sentence
45

46. Final founding the validity LS law
through Basic Legal Meta-Rule Sentence
BLMRS
The validity of the final, highest legal meta sentence,
whose validity can not be deduce through the
application of LMRS sentences, is called the
basic legal meta-rule sentence (BLRMS).
The validity of BLMRS is to be presupposed,
namely asserted as a fact sentence.
46

47. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
BLMRS
Basic Legal
Meta-Rule Sentence
MRS
Legal Metarule Sentence
LRS
Legal Rule Sentence
FLMRS Fundamental
Legal Metarule Sentence
47
Legal meta-sentences

48. Comparison
of the results of LJ
with Kelsen’s PTL
48

49. Kelsen Yoshino
Basic LRS
Fundamental
LMRS
Basic Norm
similar solutions at the top of the system
State, Law
Computer-Application
LJ - Logical JurisprudencePL- Pure Theory
„School“ Stage of Rights and Duties
49

50. Yoshino
LMS
LRS
LOS
LFS
Formal Logic
Computer
Expert Systems
LO
State, Law
Computer-Application
LJ - Logical Jurisprudence
Stage of Rights and Duties
50
Kelsen
Textuality
PL- Pure Theory
„School“

51. Yoshino
Formal Logic
Computer
Expert Systems
LO
LMS
LRS
LOS
LFS
further supplement of LJ:
 Legal Ontologies
State, Law
Computer-Application
LJ - Logical Jurisprudence
Stage of Rights and Duties
51

52. Metalevel
State, Law
Scientific Audience
LJ - Logical Jurisprudence
Stage of Rights and Duties
52
Contract becomes valid.
[r3aA2]
A must do X for B”
becomes valid on T <-
“B may require A to
do X ” is valid &
B requires A to do X
r01, CISG46(3)
[r0]
S is valid on T <-
S becomes valid &
not (S is terminated)
Fundamental
Meta rule:
[r01]
f10
f8
f3
f3’
f22
f21
“A must repair the machine” is valid on 2010-9-15.
CISG Part 4 Art. 99 is valid
r01_bc is valid.
r0 is valid.
r01 is valid.
r3aa1 is valid.
r01 is valid.
dr3aa2 is valid.
B required A to repair the
machine on 2010-09-01.
The machine becomes out
of order on 2010-08-10.
Sale of goods
between A in New York
and B in Osaka.
The tenth instruments
of ratification was de-
posited on 1986-12-11.
CISG was adopted
on 1980-4-10 in Vienna.
B’s acceptance reached
to A on 2010-4-9.
It is not proved:
the contract is terminated.
[r3aa1]
&
Not proved: beginning time nor
condition to enter into force.
&
&
&
&
&
&
&
&
&
CISG Part 2, Art.23
& “B may require A to repair the
machine” is valid on 2010-09-15.
Contract&
Contract is valid.
CISG Part 2 is valid.
Contract is concluded.
The CISG is valid.
CISG Part 4 Art .99 (1)
Basic Legal Rules [r01_bc]
&
&
&
&
Fundamental legal
meta sentences
Positive legal
meta sentences
Positive legal
fact sentences
Outline of the Whole Process of Meta-inference of the Validity

53. Summary of LJ
• Three primitives: LJ starts from (1) legal sentences,
(2) validity as truth, and (3) inference rules and ana-
lyses a legal system in terms of 3 types of LSs
• Systemicity of law through legal reasoning
• Legal system is explained as a deductive system
• Clarifies FLMRS (fundamental legal meta rules
sentences)
• Inference of validity between LSs in terms of meta
rule sentences and meta inference.
• Developing deductive legal knowledge bases.
53

54. Conclusions
• Legal informatics. Yoshino’s achievement is to stay
within the mainstream
• Ontologies. We suggest to concern them
• Compound Legal Formula representation and Prolog
 Critique by (Leith 2010) of expert systems
• Consideration “Norm as a meaning does not exist”
leads to a discussion
 Universalia ante rem
post rem
in rem
 FRISCO semiotic tetrahedron 54
Thought
Symbol
(representation)
Referent
(thing)
Actor

55. 55
Thank you
Vytautas.Cyras@mif.vu.lt
Friedrich.Lachmayer@uibk.ac.at
www.legalvisualization.com
http://jusletter-it.weblaw.ch/visualisierung/