This is a defeasible, rough-and-ready sense of what's "real," i.e.
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Defeasible logic is a non-monotonic logic proposed by Donald Nute to formalize defeasible reasoning. In defeasible logic, there are three different types of propositions: ; strict rules : specify that a fact is always a consequence of another; ; defeasible rules : specify that a fact is typically a consequence of another; ; undercutting defeaters : specify exceptions to defeasible rules. A priority ordering over the defeasible rules and the defeaters can be given. During the process of deduction, the strict rules are always applied, while a defeasible rule can be applied only if no defeater of a higher priority specifies that it should not.
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Three types of defeasible estates are the fee simple determinable, the fee simple subject to an executory limitation or interest, and the fee simple subject to a condition subsequent. Because a defeasible estate always grants less than a full fee simple, a defeasible estate will always create one or more future interests.
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In this evidence-based approach, knowledge must be seen as defeasible.
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But there can be defeasible generalizations (defeasible inference rules). When we say that birds can fly, we mean that it is generally the case, subject to exceptions. We are justified in making the inference and accepting the conclusion that this particular bird can fly until we find out that an exception applies in this particular case. In addition to deductive inference and defeasible inference, there is also probabilistic inference.
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A non-monotonic logic is a formal logic whose consequence relation is not monotonic. In other words, non-monotonic logics are devised to capture and represent defeasible inferences (cf. defeasible reasoning), i.e., a kind of inference in which reasoners draw tentative conclusions, enabling reasoners to retract their conclusion(s) based on further evidence.
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Although his work had considerable impact in the area of Artificial intelligence and law, Pollock was not himself interested much in jurisprudence or theories of legal reasoning, and he never acknowledged the inheritance of defeasible reasoning through H.L.A. Hart. Pollock also held informal logicians and scholars of rhetoric at a distance, though defeasible reasoning has natural affinities in argument (logic). Pollock's "undercutting defeat" and "rebutting defeat" are now fixtures in the defeasible reasoning literature. He later added "self-defeat" and other kinds of defeat mechanisms, but the original distinction remains the most popular.
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Their value and purpose would be undermined if the security was always defeasible on a transfer of his reversion by the reversioner.
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A defeasible estate is created when a grantor transfers land conditionally. Upon the happening of the event or condition stated by the grantor, the transfer may be void or at least subject to annulment. (An estate not subject to such conditions is called an indefeasible estate.) Historically, the common law has frowned on the use of defeasible estates as it interferes with the owners' enjoyment of their property and as such has made it difficult to create a valid future interest. Unless a defeasible estate is clearly intended, modern courts will construe the language against this type of estate.
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1, 2007, 1-17. views knowledge as essentially defeasible. Therefore, an infinite regress is unproblematic, since any known fact may be overthrown on sufficiently in-depth investigation.
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Pollock became known as "Mr. Defeasible Reasoning" among philosophers in the two decades before his death. In Artificial intelligence, where non-monotonic reasoning had caused intellectual upheaval, scholars sympathetic to Pollock's work held him in great esteem for his early commitment and clarity. Pollock's most direct pronouncement is the paper "Defeasible reasoning" in Cognitive Science, 1987, though his non-syntactic ideas were almost fully mature in Knowledge and Justification.
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Defeaters play a central role in modern developments of defeasible reasoning. In traditional deductive reasoning the only way the conclusion of a valid argument can be false is if at least one of the premises is false. A defeasible argument, on the other hand, allows the retraction of its conclusion as new evidence is acquired without denying the truth of its premises. The evidence responsible for this retraction is called a defeater.
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If no condition suspends the vesting or there is no condition or limitation that makes the vesting defeasible, the right is considered to be vested indefeasibly at the time of death.
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A probabilistic version of the generalization, "birds can fly", might be: "There is a 75% chance that a bird will be found to be able to fly" or "if something is a bird it probably can fly". The probabilistic version is also capable of being defeated (it is defeasible), but it includes the idea that the uncertainty might be quantifiable according to axioms of probability. (An exact number need not be attached as in the first example.) In some theories, argumentation schemes are mostly schemes for argumentation with defeasible inference although there could be schemes for specialized areas of discourse using other forms of inference, such as probability in the sciences. For most or all everyday arguments, the schemes are defeasible.
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If previous grantors of a fee simple estate do not create any conditions for subsequent grantees, then the title is called fee simple absolute. A fee simple absolute is the highest estate permitted by law and it gives the holder full possessory rights and obligations now and in the future. Other fee simple estates in real property include fee simple defeasible (or fee simple determinable) estates. A defeasible estate is created when a grantor places a condition on a fee simple estate (in the deed).
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229, 29 June, 4 & 5 Phil. & Mar. (1557) illustrates this point. In that case, the debtor (now plaintiff in equity) had given a bond to pay a sum of £400, “defeasible if 20 marks (£13 s.
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In later years, Transaction Logic was extended in various ways, including concurrency,A.J. Bonner and M. Kifer (1996), Concurrency and communication in Transaction Logic, Joint Intl. Conference and Symposium on Logic Programming, Bonn, Germany, September 1996 defeasible reasoning,P.
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1989: 11–15 but specific non-monotonic logics such as defeasible logicBenjamin Johnston, Guido Governatori: Induction of Defeasible Logic Theories in the Legal Domain. Proceedings of the Ninth International Conference on Artificial Intelligence and Law 2003:204–213 have also been used. Following the development of abstract argumentation,Phan Minh Dung: On the Acceptability of Arguments and its Fundamental Role in Nonmonotonic Reasoning, Logic Programming and n-Person Games. Artificial Intelligence 77(2): 321–358 (1995) however, these concerns are increasingly being addressed through argumentation in monotonic logic rather than through the use of non-monotonic logics.
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To address this issue a number of rule-based and reasoning-based approaches have been applied to sentiment analysis, including defeasible logic programming. Also, there is a number of tree traversal rules applied to syntactic parse tree to extract the topicality of sentiment in open domain setting.
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Law often concerns issues about time, both relating to the content, such as time periods and deadlines, and those relating to the law itself, such as commencement. Some attempts have been made to model these temporal logics using both computational formalisms such as the Event CalculusR. Hernandez Marin, G. Sartor, Time and norms: a formalisation in the event-calculus, in: Proceedings of the Seventh International Conference on Artificial Intelligence and Law, ACM, New York, 1999, pp. 90–100. and temporal logics such as defeasible temporal logic.G. Governatori, A. Rotolo, G. Sartor, Temporalised normative positions in defeasible logic, in: Proceedings of the Tenth International Conference on Artificial Intelligence and Law, ACM Press, New York, 2005, pp. 25–34.
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Since, in contrast to the Torrens system, the registry is merely a record of all instruments related to the land, the "owner" as shown on the land registry record (or common known as "land search record" in Hong Kong) does not necessarily mean that he has a "good title", which means a title that is not defeasible or potentially defeasible. In a sale and purchase of land, a vendor is required to show a "good title" to the purchaser. Since the land search record is not conclusive, it leads to problems when a vendor has to prove his title, in particular when the land is old or involves multiple encumbrances. This may lead to litigation if the parties cannot agree on whether a good title is shown.
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Grice attributed a number of properties to conversational implicatures: They are defeasible (cancellable), meaning that the implicature may be cancelled by further information or context. Take the examples from above: : That cake looks delicious. +> I would like a piece of that cake. : versus: That cake looks delicious, but it looks too rich for me.
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Many reasoning systems employ deductive reasoning to draw inferences from available knowledge. These inference engines support forward reasoning or backward reasoning to infer conclusions via modus ponens. The recursive reasoning methods they employ are termed ‘forward chaining’ and ‘backward chaining’, respectively. Although reasoning systems widely support deductive inference, some systems employ abductive, inductive, defeasible and other types of reasoning.
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An expert in pure and applied logic, his research largely focused on issues in defeasible reasoning and non-monotonic logic. His more recent work in philosophy of logic was concerned with applications of generalized quantifier theory and abstraction principles to the foundations of arithmetic in the more general context of Fregean foundations, as well as making contributions to Frege scholarship.
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Although aided by a strong tail wind from AI and a few contemporary like minded philosophers (e.g., Donald Nute, Nicholas Asher, Bob Causey), it is certain that defeasible reasoning went from the obscure to the mainstream in philosophy because of John Pollock, in the short time between the publication of Knowledge and Justification and the second edition of Contemporary Theories of Knowledge.
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The study of argument in the field of argumentation theory since Perelman and Olbrechts-Tyteca's The New Rhetoric and Stephen Toulmin's The Uses of Argument, both first published in 1958, has been characterized by a recognition of the defeasible, non-monotonic nature of most ordinary everyday arguments and reasoning. A defeasible argument is one that can be defeated, and that defeat is achieved when new information is discovered that shows that there was a relevant exception to an argument in the presence of which the conclusion can no longer be accepted. A common example used in textbooks concerns Tweety, a bird that may or may not fly: :(All) birds can fly; :Tweety is a bird; :Therefore, Tweety can fly. The argument above (with the addition of "All", which is shown in parentheses) has the form of a logical syllogism and is, therefore, valid.
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His epistemic norms are governed by defeasible reasoning; they are ceteris paribus conditions that can admit exceptions. Several other epistemologists (notably at Brown University, such as Ernest Sosa,and especially Roderick Chisholm), as well as his Arizona colleague Keith Lehrer, had written about defeasibility and epistemology. But Pollock's book, which combined a broad scope and a crucial innovation, brought the ideas into the philosophical mainstream.
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Being based on F-logic and HiLog implies that object-oriented syntax and higher-order representation are the major features of the system. Flora-2 also supports a form of defeasible reasoning called Logic Programming with Defaults and Argumentation Theories (LPDA).H. Wan , B. Grosof , M. Kifer , P. Fodor , S. Liang (2009), Logic Programming with Defaults and Argumentation Theories. 25th International Conference on Logic Programming (ICLP 2009), July 2009.
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Nomic Probability and the Foundations of Induction, Oxford, 1990 was Pollock's deep investigation of the relationship between defeasible reasoning and the estimation of probability from frequencies (direct inference of probability). It is a maturation of ideas originally found in a 1983 Theory and Decision paper. This work must be compared to Henry E. Kyburg's theories of probability, although Pollock believed that he was theorizing about a broader variety of statistical inferences.
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Fee simple estates may be either fee simple absolute or defeasible (i.e. subject to future conditions) like fee simple determinable and fee simple subject to condition subsequent; this is the complex system of future interests (q.v.) which allows concepts of trusts and estates to elide into actuarial science through the use of life contingencies. Estate in land can also be divided into estates of inheritance and other estates that are not of inheritance.
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Flora-2 is an object-oriented knowledge representation and reasoning system based on F-logic and incorporates HiLog, Transaction logic, and defeasible reasoning. Logtalk is an object-oriented logic programming language that can use most Prolog implementations as a back-end compiler. As a multi-paradigm language, it includes support for both prototypes and classes. Oblog is a small, portable, object-oriented extension to Prolog by Margaret McDougall of EdCAAD, University of Edinburgh.
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In property law and real estate, a future interest is a legal right to property ownership that does not include the right to present possession or enjoyment of the property. Future interests are created on the formation of a defeasible estate; that is, an estate with a condition or event triggering transfer of possessory ownership. A common example is the landlord-tenant relationship. The landlord may own a house, but has no general right to enter it while it is being rented.
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The position of the common law courts was adopted and codified in the Administration of Justice Act 1696 and later the Administration of Justice Act 1705. Accordingly, procedurally relief in relation to such bonds was thereafter administered entirely by the common law courts without intervention by the courts of equity. However, the courts of equity began to develop concurrent remedies for relief from forfeiture. With the decline of the use of defeasible bonds the procedural mechanics became increasingly applied to liquidated damages clauses.
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Historically, opinion on the appeal to authority has been divided: it is listed as a valid argument as often as a fallacious argument in various sources, as some hold that it is a strong or at least valid defeasible argumentSalmon, Merrilee Introduction to Logic and Critical Thinking (2012) Cengage Learning and others that it is weak or an outright fallacy. If all parties agree on the reliability of an authority in the given context it forms a valid inductive argument.
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Loui was a leading advocate of defeasible reasoning in artificial intelligence (see also argument and argumentation theory) and a leading proponent of scripting languages. He was co-patentor of a deep packet inspection hardware device that could read and edit the contents of packets as they stream through a network. This was a key technology sought by the DARPA Information Awareness Office and Disruptive Technology Office under Total Information Awareness. Loui also consulted on Cyc, a famous Artificial Intelligence program devised by Doug Lenat.
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In the past few centuries, some statistical methods have been developed, for reasoning in the face of uncertainty, as an outgrowth of methods for eliminating error. This was an echo of the program of Francis Bacon's Novum Organum of 1620. Bayesian inference acknowledges one's ability to alter one's beliefs in the face of evidence. This has been called belief revision, or defeasible reasoning: the models in play during the phases of scientific method can be reviewed, revisited and revised, in the light of further evidence.
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Many of the names of argumentation schemes may be familiar because of their history as names of fallacies and because of the history of the teaching of fallacies in critical thinking and informal logic courses. In his groundbreaking work, Fallacies, C. L. Hamblin challenged the idea that the traditional fallacies are always fallacious.See chapter 1 in: Subsequently, Walton described the fallacies as kinds of arguments; they can be used properly and provide support for conclusions, support which is, however, provisional and the arguments defeasible. When used improperly they can be fallacious.
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Conversational implicatures are classically seen as contrasting with entailments: They are not necessary or logical consequences of what is said, but are defeasible (cancellable). So, B could continue without contradiction: : B: But unfortunately it's closed today. An example of a conventional implicature is "Donovan is poor but happy", where the word "but" implicates a sense of contrast between being poor and being happy. Later linguists introduced refined and different definitions of the term, leading to somewhat different ideas about which parts of the information conveyed by an utterance are actually implicatures and which aren't.
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Conventional implicatures, briefly introduced but never elaborated on by Grice, are independent of the cooperative principle and the four maxims. They are instead tied to the conventional meaning of certain particles and phrases such as "but, although, however, nevertheless, moreover, anyway, whereas, after all, even, yet, still, besides", verbs such as "deprive, spare", and possibly also to grammatical structures. (Such words and phrases are also said to trigger conventional implicatures.) In addition, they are not defeasible, but have the force of entailments. An example: : Donovan is poor but happy.
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Pollock devoted considerable time later in his career to a software project called OSCAR, an artificial intelligence software prototype he called an "artilect". OSCAR was largely an implementation of Pollock's ideas on defeasible reasoning, but it also embodied his less well known and often unpublished ideas about intentions, interests, strategies for problem solving, and other cognitive architectural design. OSCAR was a LISP-based program that had an "interest-based" reasoner. Pollock claimed that the efficiency of his theorem-prover was based on its unwillingness to draw "uninteresting" conclusions.
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Scalar implicatures typically arise where the speaker qualifies or scales their statement with language that conveys to the listener an inference or implicature that indicates that the speaker had reasons not to use a stronger, more informative, term. For example, where a speaker uses the term "some" in the statement, "Some students can afford a new car.", the use of "some" gives rise to an inference or implicature that "Not all students can afford a new car." As with pragmatic inference generally, such inferences are defeasible or cancellable – the inferred meaning may not be true, even though the literal meaning is true.
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Chartier argues in response that for many people, at least, belief in state authority is defeasible and can rightly be undermined by positive arguments against particular justifications for the authority of state-made law."In Defence of the Anarchist," Oxford Journal of Legal Studies 29.1 (2009): 115–38. Also important to his defense of anarchism is his detailed justification for the conclusion that, appearances to the contrary notwithstanding, the institutions of a consensual, polycentric legal order can enforce the law without becoming morally indistinguishable from states.Gary Chartier, "Enforcing the Law and Being a State," Law and Philosophy 31.1 (2012): 99–123.
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Since the late 20th century, European and American logicians have attempted to provide mathematical foundations for dialectical logic or argument. There had been pre-formal and partially-formal treatises on argument and dialectic, from authors such as Stephen Toulmin (The Uses of Argument), Nicholas Rescher (Dialectics), and van Eemeren and Grootendorst (pragma-dialectics). One can include the communities of informal logic and paraconsistent logic. However, building on theories of defeasible reasoning (see John L. Pollock), systems have been built that define well-formedness of arguments, rules governing the process of introducing arguments based on fixed assumptions, and rules for shifting burden.
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Brink, "Moral Realism and the Skeptical Arguments from Disagreement and Queerness," Australasian Journal of Philosophy 62 (1984) holds that moral claims imply motivation internalism (the doctrine that "It is necessary and a priori that any agent who judges that one of his available actions is morally obligatory will have some (defeasible) motivation to perform that action"Joyce, Richard (2001). The Myth of Morality, Cambridge University Press.). Because motivation internalism is false, however, so too are all moral claims. The other argument often attributed to Mackie, often called the argument from disagreement, maintains that any moral claim (e.g.
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This is, of course, a defeasible inference based on world knowledge, that is then contradicted in the following sentence. The majority of the studies done on contrast and contrastive relations in semantics has concentrated on characterizing exactly which semantic relationships could give rise to contrast. Earliest studies in semantics also concentrated on identifying what distinguished clauses joined by and from clauses joined by but. In discourse theory, and computational discourse, contrast is a major discourse relation, on par with relationship like explanation or narration, and work has concentrated on trying to identify contrast in naturally produced texts, especially in cases where the contrast is not explicitly marked.
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The claim "I am definitely a British citizen" has a greater degree of force than the claim "I am a British citizen, presumably". (See also: Defeasible reasoning.) The first three elements, claim, ground, and warrant, are considered as the essential components of practical arguments, while the second triad, qualifier, backing, and rebuttal, may not be needed in some arguments. When Toulmin first proposed it, this layout of argumentation was based on legal arguments and intended to be used to analyze the rationality of arguments typically found in the courtroom. Toulmin did not realize that this layout could be applicable to the field of rhetoric and communication until his works were introduced to rhetoricians by Wayne Brockriede and Douglas Ehninger.
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Upton, Maritime Law and Prize, p. 445 (citing the federal district court case of the Louisa Agnes which noted indecorous treatment like putting the captured crew in irons might well be defensible as necessary, under the circumstances). Officers restrained the crew to prevent pillaging defeated adversaries, or pilfering the cargo known as breaking bulk. Francis Upton's treatise on Maritime Warfare cautioned: > Embezzlements of the cargo seized, or acts personally violent, or injuries > perpetrated upon the captured crew, or improperly separating them from the > prize-vessel, or not producing them for examination before the prize-court, > or other torts injurious to the rights and health of the prisoners, may > render the arrest of the vessel or cargo, as prize, defeasible, and also > subject the tort feasor for damages therefore.
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Argument technology is a sub-field of artificial intelligence that focuses on applying computational techniques to the creation, identification, analysis, navigation, evaluation and visualisation of arguments and debates.Artificial intelligence In the 1980s and 1990s, philosophical theories of arguments were leveraged to handle key computational challenges, such as modeling non- monotonic and defeasible reasoning and designing robust coordination protocols for multi-agent systems. At the same time, mechanisms for computing semantics of Argumentation frameworks were introduced as a way of providing a calculus of opposition for computing what it is reasonable to believe in the context of conflicting arguments. With these foundations in place, the area was kick- started by a workshop held in the Scottish Highlands in 2000, the result of which was a book coauthored by philosophers of argument, rhetoricians, legal scholars and AI researchers.
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When a specified event happens, the estate may become void or subject to annulment. There are two types of defeasible estates: fee simple determinable and the fee simple subject to a condition subsequent. If the grantor uses durational language in the condition such as "to A. as long as the land is used for a park", then upon the happening of the specified event (in this case if the land is used for anything other than a park), the estate will automatically terminate and revert to the grantor or the grantor's estate; this is called a fee simple determinable. If the grantor uses language such as "but if alcohol is served", then the grantor or the heirs have a right of entry if the condition occurs, but the estate does not automatically revert to the grantor; this is a fee simple subject to a condition subsequent.
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Although penal bonds have not been used for hundreds of years, their influence on English jurisprudence continued through the development of the common law rules in relation to penalty clauses.Professor A. W. B. Simpson, The penal bond with conditional defeasance (1966) 82 LQR 392, 418-419 During their review of this area of the law in Cavendish Square Holding BV v Talal El Makdessi the Supreme Court reviewed the relevant history and its effect on subsequent jurisprudence (noting that "[t]he penalty rule in England is an ancient, haphazardly constructed edifice which has not weathered well".Makdessi [2015] UKSC 67, at para 3. With the decline of the use of defeasible bonds the procedural mechanics developed in case law and Administration of Justice Act 1696 and later the Administration of Justice Act 1705 to protect parties became increasingly applied to liquidated damages clauses, which evolved into the common law doctrine of penalties.
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Guillermo Ricardo Simari is an Argentine computer scientist born in the city of Buenos Aires. He is an international leader in Defeasible Reasoning and Argument (Logic) (see also Argumentation Theory), a national leader in Logic Programming in Argentina, and one of the leaders of Artificial Intelligence in South America. He has headed the Artificial Intelligence Research and Development Lab (LIDIA) at Universidad Nacional del Sur (Argentina) since 1990, where he has personally mentored many internationally known students, such as Juan Carlos Augusto, Alejandro J. García, Marcelo A. Falappa, Carlos I. Chesñevar, Ana G. Maguitman, Pablo R. Fillottrani, Diego C. Martínez, María Laura Cobo, Sebastian Sardiña, Marcelo L. Errecalde, Edgardo Ferretti, Sergio Alejandro Gómez, Nicolás Rotstein, Martín Moguillansky, Andrea Cecchi, Andrea Cohen, Sebastian Gottifredi, Cristhian Ariel Deagustini, Maximiliano C.D. Budán, Juan Carlos Teze, who have had a significant impact in the Spanish and non-Spanish speaking AI communities. Since December 2018, he is Universidad Nacional del Sur Professor Emeritus of Logic in Computer Science and Artificial Intelligence.
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The law originated in the fifteenth century in relation to "defeasible bonds" (sometimes called penal bonds) which were a contractual promise to pay money, which might be discharged if certain obligations were performed (and if the obligations were not performed, then the payment terms under the bond could be enforced).Professor A. W. B. Simpson, The penal bond with conditional defeasance (1966) 82 LQR 392, 418-419 However the courts of equity regarded these as what they really were - security for performance of the underlying obligation - and were prepared to restrain enforcement of such bonds where the defaulting party paid any damages due at common law.Sloman v Walter (1783) 1 Bro CC 418, at 419 per Lord Thurlow LC. In time the courts of common law began to mirror this approach and stay any proceedings on such bonds where the defendant gave an undertaking to pay damages together with interest and costs.
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Maarten Boudry and others have argued that formal, deductive fallacies rarely occur in real life and that arguments that would be fallacious in formally deductive terms are not necessarily so when context and prior probabilities are taken into account, thus making the argument defeasible and/or inductive. Boudry coined the term fallacy fork. For a given fallacy, one must either characterize it by means of a deductive argumentation scheme, which rarely applies (the first prong of the fork) or one must relax definitions and add nuance to take the actual intent and context of the argument into account (the other prong of the fork). To argue, for example, that one became nauseated after eating a mushroom because the mushroom was poisonous could be an example of the post hoc ergo propter hoc fallacy unless one were actually arguing inductively and probabilistically that it is likely that the mushroom caused the illness since some mushrooms are poisonous, it is possible to misidentify a mushroom as edible, one doesn't usually feel nauseated, etc.
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Whereas in the formal plays of dialogical logic P will loose both plays on an elementary proposition, namely the play where the thesis states this proposition and the play where he states its negation; in GTS one of both will be won by the defender. A subsequent development was launched by Johan van Benthem (and his group in Amsterdam) in his book Logic in Games, which combines the game-theoretical approaches with epistemic logic. # The argumentation theory approach of Else M. Barth and Erik Krabbe (1982), who sought to link dialogical logic with the informal logic or critical reasoning originated by the seminal work of Chaim Perelman (Perelman/Olbrechts-Tyteca 1958), Stephen Toulmin (1958), Arne Næss (1966) and Charles Leonard Hamblin (1970) and developed further by Ralph Johnson (1999), Douglas N. Walton (1984), John Woods (1988) and associates. Further developments include the argumentation framework of P.D. Dung and others, the defeasible reasoning approach of Henry Prakken and Giovanni Sartor, and pragma-dialectics by Frans H. van Eemeren and Rob Grootendorst.
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