From Pure Theory of Law to Logical Jurisprudence 2002/11/7 Kelsen Conference Hajime Yoshino Meiji Gakuin University, Tokyo

From Pure Theory of Law to Logical Jurisprudence

2002/11/7 Kelsen Conference

Hajime Yoshino

Meiji Gakuin University, Tokyo

Contents

• 1 Introduction

• 2 What is Logical Jurisprudence (LJ)

• ３ Theory of Legal Sentence

• ４ On Theory of Legal Reasoning

• ５ On Theory of Legal System

• ６ Demonstration of LES-5 based on LJ

• ７ Conclusion

Hajime Yoshino

2 Primitives of Pure Theory of Law and their difficulties3 Starting Points (primitives) of Logical Jurisprudence

1 Introduction• Hans Kelsen’s final purpose in his “Pure Theory of Law (PL)” is to

establish a scientific of law.• This enterprise has still (or much more) importance in the present

world. We should receive his torch and hold it further. He might, however, have some limitations.

• If so, we should overpass (overcome) them and develop a new, true scientific of law.

• I have attempt to make such a scientific theory of law since 1985. That is “Logical Jurisprudence (LJ)”.

• In this paper, I would like at first to present what is LJ showing the primitives of LJ and comparing starting points of LJ with that of PL.

• I would like to then discuss the theses of LJ in terms of theory of legal norm, legal reasoning and legal system, occasionally comparing them with those of PL.

• I will demonstrate the availability of LJ to realize real legal reasoning on the platform of LES-5.

• I conclude this paper suggesting our further discussions.

2. What Is Logical Jurisprudence 　 (LJ)

• Concept of logical jurisprudence– Logishe Rechtslehre in German– A developed form of “legal logic” (Juristische Logik)– It is not merely an application of logic to law but also a

scientific theory of law to establish the true science of law.

– Logical Jurisprudence has been developed through the construction of LES-5, a legal reasoning system in the field of CISG (the United Nations convention on contracts for the international sale of goods).

– Naming LJ is done by Hajime Yoshino.

Primitives of LJ

• LJ try to explain the whole legal system using minimum elements.

• LJ starts form three primitives:• (1) “sentence,”

– LJ consider that norm as a meaning does not exist.– LJ starts from sentences.

• (2) “validity” of sentence– legal validity as legal truth– “is_valid(sentence1, goal1,time1)”

• (3) “inference rule.”– Modus Ponens: （（ A ⇒ Ｂ）＆Ａ） ⇒Ｂ

Comparison of the starting points of LJ with Pure Theory of Law (PL)

• PL• Norm as a Meaning• Legal Norm[1]

• Imputation (Zurechnung)• Legal Positivism• First Norm and Second N

orm• Basis of Validity: Issued o

n the basis of Upper Norm

• Theory of Hierarchical Structure of Law

• LJ• Sentence as a sign• Law Sentence• Material Implication• Scientific Positivism• Object sentence and

meta sentence• Basis of Validity: Logical

Proof through Legal Meta Inference

• Theory of Legal Meta Rules

3 Theory of Legal Sentence

• LJ starts from legal sentence

• A legal system is to be analyzed and constructed in terms of three types of alternative fundamental concepts:

• 1) (Legal) rule sentence and (Legal) fact sentence• 2) object sentence and meta sentence• 3) element sentence and complex sentence• Existence of an obligation and the validity of the

legal object sentence (Fig.2)

Legal rule and fact sentences

• Legal rule sentences: – “∀X{a(X) ← b(X)}”. – legal consequence ←legal requirement– “∀X{become_effective(offer(X,A),T) ← reach(off

er(X,A),offeree(B,X),T)}”• Legal fact sentences:

– “b(x1)”.– reach(offer(o1,anzai),offeree(bernard,o1),4_0

5).

Legal elementary and complex sentences

• Elementary legal sentence – the smallest unit of legal sentences. – “One must drive a car under 100 km /hour on a

highway”

• Complex legal sentence– A group of legal sentences, which has an unique

name– “The United Nations Convention on Contracts of the

International Sale of Goods” – a code, parts or sections or an article of the statute– The concept of a complex legal sentence enables us

to treat the validity of legal sentence at once.

Legal object and meta sentences

• A legal object sentence describes an object.– The object in law is the obligation of a person

– “B must pay A the price of $10000” • A legal meta sentence describes about a

legal sentence – It describes the validity of a legal sentence.– “”B must pay A the price of $10000” is valid”.– “(1) This Convention applies to contracts of sale

of goods between parties whose places of business are in different States : (a) when the States are Contracting States; or … ”

Obligation of persons as ultimate normative state of affairs

• Law ultimately prescribes the obligation of persons.• People’s conduct is ultimately regulated by obligations

given by law.• LJ agrees with Kelsen as far as he says that the

obligation is essential in the legal world.• However, the problem of the existence of the obligation

might cause of philosophical confusing discussion.• What is that legal obligations exist ?• LJ considers: that a legal obligation exist means is that

the legal object sentence, which describe the relevant obligation, is valid.

Figure 2: The Existence of an Obligation and the validity of the object legal sentence

events legal meta sentencelegal object sentence

There is no obligation. No legal object sentenceis valid.

There is no obligation No legal object sentenceis valid.

"Xi is obligatory"is terminated

"Xi is obligatory"becomes validevent1

event2

t1

t0

T

t2

t3

Obligation Xturns up

Obligation Xis expired

Obligation X exists.

"X is obligatory" is valid

"X is ob-ligatory"is valid.

X is obli-gatory

5 On Theory of Legal Reasoning

• Legal Reasoning as development process of legal sentences

• Legal sentences are developed to specialize or concretize other legal sentence.

• A legal sentence is set to systematize legal sentences (or to bring them into logical system)

• Setting of legal sentences is related to logical proof. They are set to establish logical proof.

Statutes（ Abstract law）

Legal interpretation（ Concretized law）

Facts described

Event

Creation

Creation

Reasoning of legal creation

Legal Reasoning of Law Applicationas a process of development of legal sentences

Purpose of law

Purpose of law

Concretejustice

Concretejustice

Reasoning of legal

justification

Legal decision

Individual law

LAW　

Statutes

Legal decision

Interpretation (for the present case)

Legally confirmed facts

Described facts

Event

Interpretation (Precedents)

Legal Principles

Common Knowledge of Legal Concept

Create

Create

Create

Create

Reason

ing of legal

Creation

Legal Reasoning Structure

Back and forth

ViewingPurpose of lawPurpose of law

Concrete justiceConcrete justice

Rea

son

ing

of le

gal

just

ific

atio

n

Offer becomes effective←offer is reached

Contract is concluded

Indication of intention is reached←It arrives in mailbox

Offer becomes effective

Offer arrives in mailbox

Event

Indication of intention becomes effective←It is reached

Contract is concluded←Offer becomes effective

& Acceptance becomes effective

Indication of intention ←Offer

Create

Create

Create

Create

Reason

ing of legal

creation

Legal Reasoning Structure– Example of Concluding Contracts

Back and

forth viewingPurpose of lawPurpose of law

Concrete justiceConcrete justice

Rea

son

ing

of le

gal

just

ific

atio

n

Logical Structure of Reasoning of Justification and Creation

• Reasoning of legal justification– Modus Ponens: （（ A → Ｂ）＆Ａ）→Ｂ

• Reasoning of legal creation– Abduction and – induction– falsification ： Modus Tollens: （ ( Ａ→Ｂ）

＆～Ｂ）→～Ａ

6 On Theory of Legal System• The law require a legal system as a deductive system so that a

judgment is, in legal reasoning, justified from the legal system together with the relevant facts of a event.

• How legal order is to be systematized as a deductive system, that has been a target of legal philosophical studies.

• LJ analyze and construct a legal system in terms of above three primitives including three types of alternative legal sentence.

• LJ succeeded in demonstrating the legal system as a deductive system on those basis.

• Thereby, the concept of validity of legal sentences and legal meta inference play a important role.

• The final target of legal reasoning is to prove the validity of object sentences, to identify what kind of sentences describing obligation are valid.

• On that way, various legal state of affairs is to be proved as well.

Hajime Yoshino

(This requirement implies the postulate of non-contradiction of legal sentences.)

Legal meta inference

• Legal sentence, which is applied to solve a problem, is to be valid. In other words:

• Only valid legal sentence can be applied as the premises of the legal inference.

• The inference, which decide whether the legal sentence applied is valid, is called legal meta inference.

The validity relationship between legal sentences

• The validity of a legal object sentence is based on the description of the validity in the legal meta sentence.

• The validity of this legal meta sentences is prescribed by other legal meta sentences.

• A legal meta sentence that prescribes the validity of a legal meta sentence can be called a higher or upper level legal meta sentence.

• The validity of each legal meta sentence is prescribed by a higher level of legal meta sentence.

• The highest, final level of legal meta sentence can be called a “basic” or “fundamental” legal meta sentence.

• The validity of the final, highest legal meta sentence is to be set as fact[1]

Fundamental Legal meta rule sentence

• (mrl)• 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 fundamental legal meta rule sentence implicitly taken for granted all 　 regulations.

• Without this rule, no statutory legal sentence works when it comes to application.

• This rule is the most fundamental among legal meta rules enabling us to put a mere collection of legal sentences into a legal system.

Logical structure of contract law regulating changes in legal

relations• Legal rule sentences deciding that legal

sentences are valid.

• Logical structure of contract law deciding accrual of obligation

• Logical structure of contract law deciding termination of obligations

Right and Duty

Legal rule sentences prescribing “a legal sentence becomes valid”

• The accrual of validity of a complex legal sentence follows the accrual of validity of elementary legal sentences which belong to it.

• (r01) become_valid(ES,G,T) <- • element_complex_sentence(ES,CS) & become_valid(CS,G,T)

Changes of legal Relationships (Fig. 3a)

５月10日までに

引渡す義務がある

15４／

５／５

Seller・Ａ

A has aduty todeliverthe goods

B has aduty topay theprice toA by

May 10.

B mayrequireA to

deliverthegoods

Buyer・ＢＢＡ

Events＜＞ Validity of Legal Sentence＜＞ Query＜＞ Answer＜＞

query(2)

query(3)

Offer iseffective

query(1)

４／５

Offer be-comes valid

B pays the price

The goods is delivered to B

B examines the goods

A has a duty todeliverthe goodswhich conformsto the contract

A mayrequire

B to paythepricebyMay10th.

Accept. be-comes validContract becomes valid

Offer reaches to B

Acceptance reaches to A

hands over the Ａgoods to the first carrier Japanese Container Ship

duty to deli-ver the goods

There is nolegal relation

right to require todeliver the goods

right to requireto pay the price

duty ot paythe pride

duty to paythe price

right to paythe price

４／８

４／９

５／１

10５／

31５／

６／５

Figure 3: The Changes of Legal Relation

The accrual of the validity of a legal object sentence by

exercising the right

• (3AA2) "A legal sentence 'X has an obligation to do Z' becomes valid at time T,

• if a legal sentence 'Y has a right to require X to do Z' is valid, and Y exercises the right to require X to do Z at time T.”

• (rCISG46): “The buyer has a right to require the seller to remedy the lack of conformity by repair” becomes valid,

• if the goods do not conform with the contract.

Legal rule sentences prescribing “a legal sentence is terminated”

• The validity of elementary legal sentence is terminated if the complex legal sentence is terminated.

15９／

10／５

The additional period expired.

right to reqire to repair

right to claim damage


right to require to repair

( restricted )

right to requireto repairB may

declare the

contract avoided.

The right to claim

to repair is

restricted.

Exercise of claim to repair.

B may require A to repair

the machine.

query(4)

query(5)

query(6) right to claim

damage

right to declaincontract avoided

B declared the contract avoided.

claim to restituteA the machiner

11 15／ query(7)



claim to restituteB the price

query(8)

９／１

8 10／

９／１

10／１

10 10／

12 10／

12 15／

15８／

A has a duty to recover the damage for B.

B has a duty to repair the machine.

B may claim A the the damage.

The machine is operatingout of order

B noticed to A specifyingthe nature of the lack of

conformity

B asked A to repair the machine within one month.

duty to reco-ver the damage

duty to repairthe machine




duty to resti-tute the price


duty to resti-tute machine


B mayrequire Ato repair

the machine

B mayclaim A

torestitutethe pricepaid by B

A hasa duty torestitute

Bthe pricepaid by B

Exerise of right to declare contract avoided

Changes of legal Relationships (Fig. 3b’)

６　 Demonstration of LES-5 based on Logical Jurisprudence

• Go to demo on off-line.

• http://www.meijigakuin.ac.jp/~yoshino/en/

Case 8fCASE 8f1. On April 1, a New York manufacturer of agricultural machines, A (Anzai),dispatched to the Hamburg branch of a Japanese trading company, B (Bernard),a letter containing the following proposal: A will sell B a set ofagricultural machines comprised of a tractor and a rake; the price of thetractor is $50,000; A will deliver the machinery to B by May 10; B must payA the price of the machinery by May 20; the machinery will be transported byan American fright vessel.2. The proposal reached B's letter box on April 8.3. On April 9, B telephoned A and said, "I accept your offer. However, Iwant the machinery transported by Japanese container ship."4. A delivered the agricultural machinery to a Japanese container ship atthe port of New York on May 1.5. The machinery was delivered to B's Hamburg branch on May 31.6. B examined the machinery on June 5.7. B paid A $58,000 on May 20. (The market price of the rake was $8,000).8. On August 10, the machinery malfunctioned because of a defectiveconnecting gear.9. B notified A of the malfunction immediately.10. On September 1, B demanded that A repair the lack of conformity withinone month.11. A did not repair the defect by October 1.12. On October 10, B declared the contract avoided.13. On December 10, B made restitution of the machine to A.14. On December 20, A made restitution of the $58,000 price to B, plusinterest, and gave compensation for damages B had suffered.

Queries

• At each of the points of time indicated below, what is the legal relation that exists between A and B?

• 1: April 5th• 2: April 15th • 3: May 5th • 4: August 15th• 5: September 15th • 6: October 5th• 7: November 15th • 8: December 15th• 9: December 25th

CISG Articles • The following articles of the CISG apply to the case:• Article 15(1) An offer becomes effective when it reaches the offeree.• (2) An offer, even if it is irrevocable, may be withdrawn if the with

drawal reaches the offeree before or at the same time as the offer.Article 16(1) Until a contract is concluded an offer may be revoked if the revocation reaches the offeree before he has dispatched an acceptance.

• Article 18(2) An acceptance of an offer becomes effective at the moment the indication of assent reaches the offeror. … .

• Article 23• A contract is concluded at the moment when an acceptance of an offer

becomes effective in accordance with the provisions of this Convention.

• Article 31• If the seller is not bound to deliver the goods at any other particul

ar place, his obligation to deliver consists:• (a) if the contract of sale involves carriage of the goods - in handi

ng the goods over to the first carrier for transmission to the buyer;

CISG Articles• Article 38• (1) The buyer must examine the goods, or cause them to be

examined, within as short a period as is practicable in the circumstances.

• Article 39• (1) The buyer loses the right to rely on a lack of

conformity of the goods if he does not give notice to the seller specifying the nature of the lack of conformity within a reasonable time after he has discovered it or ought to have discovered it.

• Article 45• (1) If the seller fails to perform any of his obligations

under the contract or this Convention, the buyer may:• (a) exercise the rights provided in articles 46 to 52;• (b) claim damages as provided in articles 74 to 77.• (2) The buyer is not deprived of any right he may have to

claim damages by exercising his right to other remedies.

CISG Articles• Article 46• (1) The buyer may require performance by the seller of his obligations

unless the buyer has resorted to a remedy which is inconsistent with this requirement.

• (2) If the goods do not conform with the contract, the buyer may require delivery of substitute goods only if the lack of conformity constitutes a fundamental breach of contract and a request for substitute goods is made either in conjunction with notice given under article 39 or within a reasonable time thereafter.

• (3) If the goods do not conform with the contract, the buyer may require the seller to remedy the lack of conformity by repair, unless this is unreasonable having regard to all the circumstances. A request for repair must be made either in conjunction with notice given under article 39 or within a reasonable time thereafter.

• Article 49• (1) The buyer may declare the contract avoided:• (a) if the failure by the seller to perform any of his obligations un

der the contract or this Convention amounts to a fundamental breach of contract; or

• (b) in case of non-delivery, if the seller does not deliver the goods within the additional period of time fixed by the buyer in accordance with paragraph (1) of article 47 or declares that he will not deliver within the period so fixed.

Solutions • 1) On April 5th, there is no legal relation between the seller A (Anzai) and

the buyer B (Bernard)• 2) On April 15th, A has a duty to deliver the farming machine to B by May 10t

h and B has a duty to pay the price $50,000 to A by May 20th, while B has right to require A to deliver the goods to B and A has the right to require B to pay the price to A by May 10th.

• 3) On May 5th, B has a duty to pay the price $50000 to A by 20 May, while A has right to require B to pat the price to A by 10 May.

• 4) On August 15th, A has a duty to recover the damage, while B has right to claim A the damage and B has right to require A to repair the machine.

• 5) On September 15th, A has a duty to recover the damage and a duty to repair the machine, while B has right to claim A the damage and B has the right to require A to repair the machine which is restricted to exercise.

• 6) On October 5th, A has a duty to recover the damage and a duty to repair the machine, while B has right to claim A the damage, B has right to require A to repair the machine and B has a right to declare the contract avoided.

• 7) On November 15th, A has a duty to recover the damage and a duty to restitute the price paid by B, and B has a duty to restitute the machine delivered by A, while B has a right to claim A the damage and a right to require A to restitute the price, and A has right to require B to restitute the machine.

• 8) On December 15th, A has a duty to restitute the price paid by B, while B has right to require A to restitute the price.

• 9) On December 25th, there is not legal relation between A and B on the contract.




15４／

５／５

Seller・Ａ



May 10.

B mayrequireA to

deliverthegoods

Buyer・ＢＢＡ


query(2)

query(3)

Offer iseffective

query(1)

４／５


B pays the price




A mayrequire



Offer reaches to B










４／８

４／９

５／１

10５／

31５／

６／５


Changes of legal Relationships (Fig. 3b)

A has a duty todeliver

the goodswhich

conformsto the contract

９／ 15

10／５






( restricted )


declare the

contract avoided.

The right to claim

to repair is

restricted.



the machine.

query(4)

query(5)


damage




11／ 15 query(7)




12／ 25

query(8)

query(9)

９／１

8／ 10

９／１

10／１

10／ 10

12／ 10

12／ 20

12／ 15

８／ 15


B has a duty to

repair the machine.

B ma

y cl

aim

A th

e th

e da

mage

.



conformity


A restituted theprice paid by B.

A recovered the damge.B restituted the machine.


duty to repairthe machineduty to reco-ver the damage

duty to repairthe machineduty to reco-ver the damage







the machine

B has a duty to

restitute A the

machine.

B mayclaim A


A may claim B to

restitute the

machine delivered

by A.


Bthe pricepaid by B


15９／

10／５






( restricted )


declare the

contract avoided.

The right to claim

to repair is

restricted.



the machine.

query(4)

query(5)


damage




11 15／ query(7)




query(8)

９／１

8 10／

９／１

10／１

10 10／

12 10／

12 15／

15８／


B has a duty to repair the machine.

B may claim A the the damage.



conformity












the machine

B mayclaim A



Bthe pricepaid by B


Changes of legal Relationships (Fig. 3b’)




15４／

５／５

Seller・Ａ



May 10.

B mayrequireA to

deliverthegoods

Buyer・ＢＢＡ


query(2)

query(3)

Offer iseffective

query(1)

４／５


B pays the price




A mayrequire



Offer reaches to B










４／８

４／９

５／１

10５／

31５／

６／５


7. Realizing a legal reasoning system on the CISG

• The clarification of logical structure of the contract law is applied to construct a legal reasoning system on the CISG (LES5).

• The relevant knowledge is written at first in the form of logical flow chart and the represented in CPF in Knowledge Base.

• The inference system and explanation system is written in logic programming.

• The system can deduce states of legal relationships at any time point of cases as results of the application of the CISG to concrete cases.

• It can explain the reason of the deduction.• The systematization of law in LES5 might prove the legitimacy

and powerfulness of LJ.

８ Conclusion

7. Conclusion• LJ starts from three primitives: legal sentences,

the validity and inference rules.• LJ identifies the three sorts of legal sentences:

rule and fact sentences, object and meta sentences, elementary and complex sentences and.

• On the basis of these conceptions, the basic structure of legal knowledge has been clarified.

• By taking up the CISG as an example, the structure of contract law is thus clarified in terms of LJ.

• The study results of knowledge clarification by LJ are put into computer and a legal reasoning system LES5 has been developed, which could prove the legitimacy and power of LJ.

• I would suggest that LJ could develop the science of law cooperating with artificial intelligence approach to law.

yoshino:

On these way of formalization, the change of legal relations is described as a change of the validity of legal object sentences that describes obligations.

On the formalization, the fundamental legal meta rule sentence is confirmed under which every other legal meta rules are systematized.

Thus I clarified the logical structure of contract law system which can deductively prove the change of the legal relation along with the progress of events.

yoshino:

On these way of formalization, the change of legal relations is described as a change of the validity of legal object sentences that describes obligations.

On the formalization, the fundamental legal meta rule sentence is confirmed under which every other legal meta rules are systematized.

Thus I clarified the logical structure of contract law system which can deductively prove the change of the legal relation along with the progress of events.

Conclusion• I clarified the structure of contract law by

taking up the CISG as an example from the view point of Logical Jurisprudence.

• By using three standards of legal sentences, I explicated the basic structure of legal knowledge which enables us to systematize contract law.

• Applying the frame to a　 cases,I formalized the change of legal relation as a change of the validity of legal object sentences that describes obligations.

• On the formalization, I found the fundamental legal meta rule sentence under which every other legal meta rules are systematized.

• Thus I clarified the logical structure of contract law system which can deductively prove the change of the legal relation along with the progress of events.

Documents

From Pure Theory of Law to Logical Jurisprudence 2002/11/7 Kelsen Conference Hajime Yoshino Meiji Gakuin University, Tokyo