ISSN 1995-6134 UDC 340:16 DOI: http://doi.org/10.5281/zenodo.5529523 O.V. TIAGLO, Professor, Chair of Social Sciences and Humanities, Kharkiv National University of Internal Affairs, Doctor of Philosophy, (Full) Professor, Kharkiv, Ukraine; e-mail: olexti@yahoo.com; ORCID: http://orcid.org/0000-0003-0721-1153 THINK LIKE A JURIST: WHAT DOES IT MEAN? О.В. ТЯГЛО, професор кафедри соціально-гуманітарних дисциплін Харківського національного університету внутрішніх справ, доктор філософських наук, професор, Харків, Україна; e-mail: olexti@yahoo.com; ORCID: http://orcid.org/0000-0003-0721-1153 ДУМАЙ ЯК ЮРИСТ: ЩО ЦЕ ОЗНАЧАЄ? АНОТАЦІЇ (ABSTRACTS), КЛЮЧОВІ СЛОВА (KEY WORDS) Problem statement. This article deals with the general problem of the connection between legal thinking, legal argumentation and, on the other hand, logic. Although this connection seems clear and undeniable since ancient times, various discussions about it continue to this day. The purpose is to explore one important aspect of this connection, namely, does traditional formal logic determine the relevant form of a jurist's thinking and argumentation completely? To reach this purpose, the method of comparative analysis is employed both synchronically and diachronically. First, in order to substantiate the importance of the issue, a diachronic comparison of several basic approaches is carried out (G.W. von Leibniz, O.W. Holmes Jr., etc.). Then a comparative analysis of the views of some contemporary experts is carried out, especially Ilmar Tammelo and Stephen Toulmin. As a result, it is argued that there is special legal validity in the field of law. Legal validity is determined primarily not by the value of the formal or material true, but by the value of the right directly and mainly. It differs essentially from formal-logical validity. Legal validity is not the subject of formal logic, but special legal logic and, more broadly, informal logic. It is pointed out that traditional formal logic does not determine the relevant form of legal thinking and argumentation completely, because there is the essential difference between formal-logical validity and legal validity. In other words, formal logic is neither sufficient nor necessary to think like a jurist. In this regard, it is shown that the logical standard of proof is not sufficient to determine the relevant form of valid legal proof, for example, proof beyond a reasonable doubt. Moreover, there are at least three kinds of legal proof – not only proof without reasonable doubt, but also proof by clear and convincing evidence, proof by the preponderance of the evidence. Each of them has its own special standard, which differs significantly from the formal-logical one. The conclusion is this: one cannot say that formal logic is useless in the field of law; however, in order to think and argue like a successful jurist, one must grasp and use special legal logic without any exceptions (legal logic belongs to the contemporary informal logic domain). Key words: legal thinking; legal argumentation; legal validity; legal logic; formal-logical validity; formal logic; informal logic *** Постановка проблеми. У статті досліджується загальна проблема зв’язку юридичного мислення, юридичної аргу- ментації та, з іншого боку, логіки. Хоча цей зв'язок з давніх давен видається ясним і беззаперечним, дотепер щодо нього тривають різноманітні дискусії. Моя мета полягає у тому, щоб дослідити один важливий аспект цього зв’язку, а саме: чи детермінує традиційна формальна логіка релевантну форму мислення й аргументації юриста повністю? Для досягнення цієї мети метод компаративного аналізу використовується синхронно і діахронно. Спершу в обґрун- туванні важливості дослідження виконується діахронне порівняння низки базових підходів (Г.В. фон Ляйбніц, О.В. Холмс мол. та ін). Потім виконується компаративний аналіз поглядів кількох сучасних фахівців, зокрема Ільмара Таммело й Стівена Тулміна. В результаті аргументовано, що у полі права існує особлива юридична валідність. Юридична валідність переважно детермінована не цінністю формальної чи матеріальної істини, а безпосередньо і головно цінністю права. Вона істотно відрізняється од формально-логічної валідності. Юридична валідність є пред- метом не формальної логіки, а особливої юридичної логіки та, ширше, неформальної логіки. Підкреслено, що фор- © Tiaglo O.V., 2021 24 Forum Prava, 2021. 70(5). 24–28 Open access under CC BY license (Research Article) ISSN 1995-6134 мальна логіка не детермінує релевантну форму юридичного мислення й аргументації повністю, оскільки існує істотна відмінність між формально-логічної валідністю та юридичною валідністю. Іншими словами, формальна логіка є ані достатньою, ані необхідною для того, щоб думати як юрист. В такому зв’язку показано, що логічний стандарт дове- дення не є достатнім для визначення релевантної форми валідного юридичного доведення, наприклад, доведення поза розумним сумнівом. Більше того, існують щонайменше три види юридичного доведення – не тільки доведення поза розумним сумнівом, а й доведення через ясні й переконливі докази, доведення через перевагу у доказах. Ко- жен з них має свій особливий стандарт, який суттєво відрізняється од формально-логічного. Висновок такий: не можна сказати, що формальна логіка у полі права не потрібна; однак задля того, щоб думати й аргументувати як ус- пішний юрист слід зрозуміти юридичну логіку та користуватися нею без будь-яких виключень (юридична логіка нале- жить до області сучасної неформальної логіки). Ключові слова: юридичне мислення; юридична аргументація; юридична валідність; юридична логіка; формально-логічна валідність; формальна логіка; неформальна логіка Problem statement style of mathematicians.11Moreover, this manner A jurist thinks and argues in a multidimensional was proclaimed the general standard not only for configuration space. This configuration space has all jurists, but also for philosophers. not only physical space-time dimensions, but also Two centuries later, the well-known American legal, logical and rhetorical ones. My article deals judge and legal scholar Oliver Wendell Holmes Jr. only with the logical dimension of legal thinking and proposed a completely different approach. argumentation. The life of the law has not been logic: it has It seems obvious that proper legal thinking and been experience. The felt necessities of the time, the prevalent moral and political theories, intuitions corresponding argumentation must be correct both of public policy, avowed or unconscious, even the in legal content and in the relevant form. However, prejudices which judges share with their fellow- is this relevant form, that is, all the elements and men, have had a good deal more to do than the due structure of a jurist's thinking, determined by syllogism in determining the rules by which men traditional formal logic completely? More broadly, should be governed. The law embodies the story of what the connection is between legal thinking, legal a nation's development through many centuries, argumentation and, on the other hand, logic, espe- and it cannot be dealt with as if it contained only cially formal logic? the axioms and corollaries of a book of mathemat- Without plunging into the foggy depths of histo- ics (Holmes 2011 : 5). ry, let's consider the authentic statement of Gott- Holmes' main idea is that real law, professional fried Wilhelm von Leibniz, who had a legal educa- thinking, argumentation and decision-making by tion and was well acquainted with legal practice of real jurists are not determined by logic. More accu- the 17th rately, none of this is completely determined by the century. logic akin to mathematics, that is, formal logic. We may even boldly advance an odd but true Since the time of Holmes, this approach has had paradox, that there are no authors whose manner many supporters, especially in the domain of of writing resembles the style of Geometers more common law. than the style of the Roman jurisconsults whose Nevertheless, in 1955, the Estonian-Australian fragments are found in the Pandects. After granting logician Ilmar Tammelo insisted that juristic logic is them certain assumptions based on some custom, formal logic employed in legal reasoning. It does or else, to be sure, on some rule established among not constitute a special branch, but is one of the them, we admire these jurists for their consistency special application of formal logic (Tammelo 1955 : and applications of logic … (Leibniz 1951 : 38). It seems clear that Leibniz evaluated the appli- 11"Even if it is only a question of probabilities we can cations of logic by the Roman jurists very highly. always determine what is most probable on the given premises. True this part of useful logic is not established The relevant manner, or essentially the logical form anywhere, but it is put to wonderful uses in practice when of thinking and, naturally, writing, of the jurists was there are hypotheses, indications, and conjectures in- volved in ascertaining degrees of probability among a evaluated as very resemble to the demonstrative number of reasons appearing on the one side or another of some important deliberation", – Leibniz pointed out (ibid.). Today there is some reason to insist, this piece of useful logic was an early embryo of special legal logic (Tiaglo 2015 : 242). 25 Forum Prava, 2021. 70(5). 24–28 (Research Article) ISSN 1995-6134 278). Hans Kelsen, the renowned theorist and phi- jurisprudence rather than mathematics should be losopher of law, strongly supported this approach introduced and expediently used (Toulmin 1958 : (Kelsen 1979 : 216). This is contrary to the ap- 10, 147). proach proposed by Holmes. Over time, this trend has spawned informal logic. The above examples demonstrate very hetero- Informal logic designates that branch of logic geneous approaches to understand the connection whose task is to develop non-formal standards, between legal thinking, legal argumentation and, criteria, procedures for the analysis, interpretation, on the other hand, logic, in particular formal logic. evaluation, critique and construction of argumenta- How to analyze and assess this heterogeneity to- tion in everyday discourse … (Johnson and Blair day? Which approach is more fitting for a nowa- 2000 : 94). It should be added that everyday dis- days jurist? course includes also "stylized" sub-discourses of Is formal logic sufficient to think like a jurist? the special sciences or professional activities, for Formal logic, by definition, is sufficient to think instance, legal activity. like a jurist only if any legal problem and corre- To discuss the issue deeper, let's take into ac- sponding argumentation is given the relevant form count the statement that Ilmar Tammelo insisted on. solely using a set of basic norms and standards of The problem of validity is wider than the prob- this logic. Considering this condition, let's analyze lem of material or formal truth, because we can the following passage, proposed by the contempo- speak of validity also in relation to other values rary American jurist and legal scholar Ruggiero J. than the value of the true (e.g., in relation to the Aldisert. good, the right, and the beautiful) (Tammelo 1955 No one is suggesting that briefs can be written, : 280). arguments made and cases decided solely by ref- It is quite clear that formal truth and, respective- erence to the canons of logic. Where this so, the ly, formal-logical validity are neither unique nor pri- legal profession would simply move to analysis by oritized absolutely. computer, because the computer is the paradigm According to Toulmin, validity is an intra-field, of formal logic. Value judgments reflecting the not an inter-field notion. Arguments within any field views of advocates and judges form the critical de- can be judged by standards appropriate within that cisional points in the law. Rules of logic do not field, and some will fall short; but it must be ex- make these decisions. They are simply meant to pected that the standards will be field-dependent, implement them, when these judgments are made, and that the merits to be demanded of an argu- the formal reasoning process sets in to test the va- ment in one field will be found to be absent (in the lidity of the propositions constituting the argument nature of things) from entirely meritorious argu- (Aldisert 1997 : 3). ments in another (Toulmin 1958 : 255). Aldisert supports the approach proposed by Hence, in the field of law special legal validity Holmes, at least in part: the canons of formal logic exists. Legal validity is determined primarily not by are not sufficient to decide on any value judg- the value of the formal or material truth, but by the ments, which is significant for legal thinking. More- value of the right directly and mainly. It differs from over, one can add that this insufficiency is not lim- formal-logical validity essentially. Legal validity is ited to the problem of value judgments only; it is not the subject of formal logic, but special legal log- broader and deeper. ic and, broader, informal logic (Tiaglo 2020). Principal insufficiency of traditional formal logic In this regard, one may mention, for example, to determine the relevant form of legal thinking and that legal proof is not just logical proof employed in argumentation was substantiated by Chaim Perel- legal reasoning. The logical standard of proof is not man, Stephen Toulmin and others in the middle of sufficient to determine the relevant form of real le- 20th century. For instance, Toulmin, in his well- gal proof, for instance, proof without reasonable known 1958 book "The Use of Argument", pointed doubt. Moreover, there are at least three kinds of out that from the time of Aristotle logicians have legal proof – not only proof without reasonable found the mathematical model enticing... Unfortu- doubt but also proof by clear and convincing evi- nately, an idealized logic, such as the mathemati- dence, proof by the preponderance of the evi- cal model leads us to, cannot keep in serious con- dence. Each of them has its own special standard, tact with its practical application. Along with which differs from the formal-logical one significant- idealized logic, new working logic conformed to ly (Tiaglo 2018). 26 Forum Prava, 2021. 70(5). 24–28 (Research Article) ISSN 1995-6134 Is formal logic necessary? About a century before Douglas Walton, the fa- Formal logic is not sufficient to determine the mous American lawyer Francis Wellman, in his legally valid form, all the elements and the due classic book "The Art of Cross-Examination", de- structure of legal thinking and argumentation. Is scribed cross-examination as to credit as a regular formal logic necessary here? By definition, formal procedure in court practice. logic is necessary only if any violation of the logic The preceding chapters have been devoted to norms or standards entails an essential violation of the legitimate uses of cross-examination the devel- legal thinking; any logical fallacy is unacceptable opment of truth and exposure of fraud. Cross- here. However, is it so? examination as to credit has also its legitimate use The principle of identity is a cornerstone of for- to accomplish the same end, Wellman insisted mal logic and, respectively, of formal-logical validi- (Wellman 1997 : 196). As one can see, argumen- ty. Accordingly, formal logic prohibits argumentum tum ad hominem provides a significant presupposi- ad hominem, or attacking the person, as a gross tion for the cross-examination as to credit. violation of this principle, that is, as an unaccepta- Hence, argumentum ad hominem, which is an ble logical fallacy. undoubted formal-logical fallacy, is not prohibited in Nevertheless, paragraph 2 of article 96 of the the field of law. On the contrary, it is accepted, it Criminal Procedure Code of Ukraine states that in works regularly. This demonstrates that formal log- order to prove unreliability of witness's testimonies, ic is not necessary here. a party may produce testimonies, documents as Conclusion confirmation of witness's reputation, in particular, As a result, the following conclusion seems rea- with regard to his conviction for knowingly mislead- sonable. It is not to say that formal logic is useless ing testimonies, deceit, fraud or any other acts, in the field of law. However, formal logic does not which confirm dishonesty of the witness (Kryminal- determine the relevant form of legal thinking and nyj Protsesualnyj Kodeks Ukrainy 2012). argumentation completely, because there is the What is this if not attacking the person? And this essential difference between formal-logical validity is not surprising. Douglas Walton, the well-known and legal validity. In other words, formal logic is Canadian researcher in informal logic, stated the neither sufficient nor necessary to think like a jurist. following. At the same time, in order to think and argue like a Reasoning from the personal credibility of a wit- successful jurist, one must grasp and use special ness, to a conclusion to increase or decrease the legal logic without any exceptions. Legal logic be- credibility one attaches to the proposition asserted longs to the contemporary informal logic domain. by the witness, can be a reasonable argument in some instances. It is reasonable if such a conclu- Conflict of interest sion is arrived at within the context of a larger body The author declares that there is no conflict of of evidence in a case… the fallacy is committed interest regarding the publication of this article. when the impact of the ad hominem is out of pro- Acknowledgment portion to its true weight and relevance as part of a This research received no specific grant from larger body of evidence in a case (Walton 1998 : any funding agency in the public, commercial, or 280–281). not-for-profit sectors. REFERENCES Aldisert, R. J. (1997). Logic for Lawyers. A Guide to Clear Thinking. 3rd ed. South Bend, IN: NITA. Johnson, R. H., & Blair, J. A. (2000). Informal Logic: An Overview. Informal Logic, 20(2), 93–107. https://doi.org/10.22329/il.v20i2.2262 Holmes, O. W., Jr. (2011). The Common Law. Edited by Paulo J. S. Pereira & Diego M. Beltran. Toronto: University of Toronto Law School Typographical Society. Leibniz, G. W. von (1951). Monadology and Other Philosophical Essays. Translated and edited by Paul Schrecker and Anne Martin Schrecker. Indianapolis, New York: The Bobbs-Merrill Company, Inc. Kelsen, H. (1979). Allgemeine Theorie der Normen. Wien: Manz Verlag. Kryminalnyy Protsesualnyy Kodeks Ukrayiny [Criminal Procedure Code of Ukraine]. Zakon Ukrainy (13.04.2012 No. 4651–6). https://zakon.rada.gov.ua/laws/show/4651-17 (in Ukr.). Tammelo, I. (1955). Sketch for a Symbolic Juristic Logic. Journal of Legal Education, 8(3), 277–306. http://www.jstor.org/stable/42890999 Tiaglo, A. V. (2020). O Ponimanii Dokazanelstva v Anglo-Amerikanskom Prave [On Comprehension of Proof 27 Forum Prava, 2021. 70(5). 24–28 (Research Article) ISSN 1995-6134 in Anglo-American Law]. The Bulletin of Yaroslav Mudry National Law University. Series: Philosophy, Philosophy of Law, Political Science, Sociology, 4(47), 8–23. https://doi.org/10.21564/2075- 7190.47.218952 (in Russ.). Tiaglo, O. V. (2015). Do Ponyattya Yurydychnoyi Lohiky [On the Concept of Legal Logic]. Visnyk Kharkivskoho natsionalnoho universytetu vnutrishnikh sprav, 3(70), 241–247 (in Ukr). Tiaglo, O. V. (2020). Is There a Specifically Juristic Logic? Forum Prava, 65(Suppl.), t10–t15. http://doi.org/10.5281/zenodo.4082815 Toulmin, S. E. (1958). The Uses of Argument. Cambridge: Cambridge University Press. Wellman, Francis L. (1997). The Art of Cross-Examination. New York: Touchstone. ІНФОРМАЦІЯ ПРО СТАТТЮ (ARTICLE INFO) Published in: Received: 10.11.2021 Форум права: 70 pp. 24–28 (5). Accepted: 10.12.2021 Related identifiers: Published: 14.12.2021 Available online: 14.12.2021 10.5281/zenodo.5529523 Cite as: http://forumprava.pp.ua/files/024-028- 2021-5-FP-Tiaglo_5.pdf Tiaglo, O. V. (2021). Think Like a Jurist: What does it Mean? Форум Права, 70(5), 24–28. http://doi.org/10.5281/zenodo.5529523 http://nbuv.gov.ua/UJRN/FP_index.htm _2021_5_5.pdf Tiaglo, O. V. (2021). Think Like a Jurist: What does it Mean? Forum Prava, 70(5), 24–28. http://doi.org/10.5281/zenodo.5529523 License (for files): Creative Commons Attribution 4.0 International 28 Forum Prava, 2021. 70(5). 24–28 (Research Article)