This article concerns the structure of defeasible arguments like: 'If Bob has red spots, Bob has the measles; Bob has red spots; therefore Bob has the measles.' The issue is whether such arguments have the form of modus ponens or not. Either way there is a problem. If they don't have the form of modus ponens, the common opinion to the contrary taught in leading logic textbooks is wrong. But if they do have the form of modus ponens, doubts are raised about the conventional dogma that all arguments having the form of modus ponens are deductively valid. By carefully examining arguments on both sides of the issue, reasonable doubts are raised about the view that all arguments having a modus ponens form are valid.

https://informallogic.ca/index.php/informal_logic/article/download/2571/2012

Introduction to Logic.

Are Some Modus Ponens Arguments Deductively Invalid

This paper uses argument diagrams, argumentation schemes, and some tools from formal argumentation systems developed in artificial intelligence to build a graph-theoretic model of relevance shown to be applicable (with some extensions) as a practical method for helping a third party judge issues of relevance or irrelevance of an argument in real examples. Examples used to illustrate how the method works are drawn from disputes about relevance in natural language discourse, including a criminal trial and a parliamentary debate.

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Profiles of Dialogue for Relevance

Journalistic objectivity is the definitive canon of American mainstream journalism. Yet American journalists cannot agree on what it is, how it is measured, or on how it is done. The source of the confusion is the assumption that objectivity is an ideal, absolute, impossible, incomprehensible, value-free state of being, outside of all physical, cognitive, psychological, and social contexts, where reality is perceived without distortions of any kind. This assumption is logically invalid and historically inaccurate. Journalistic objectivity evolved from the American cultural premises of egalitarianism and positive scientific empiricism through four historical stages: Nonpartisanship, Neutrality, Focus-On-Facts, and Detachment. It is possible, comprehensible, and reflects specific values. Within the context of journalism, there is no absolute truth. A “truth” is an interpretation of reality that passes three tests—coherence, correspondence and pragmatism--within a specific context. There are as many potential “truths” as there are contexts from which to determine those truths. With so many potential truths, chaos is unavoidable unless an added dimension of truth is identified. That added dimension is “objectivity.” “Objective” truths are interpretations of reality that pass the three tests of truth within the largest, most information-rich contexts. An “objective” journalist is one who gathers interpretations of reality (true or not) from the smaller contexts of news participants, and presents them faithfully and accurately to the larger context of news consumers, so that the most objective truth (the one that everyone in the large context can agree on) can be determined. In order to do this, an objective journalist has to be able to surf contexts. Therefore, “journalistic objectivity” is the ability to surf contexts, or Contextual Independence.

A reexamination of the canon of objectivity in American journalism

i on 5 18.7 18.6 23.7 22.6 28.3 28.3 30.0 25.8 23.3 22.2 6 20.0 20.0 20.7 20.7 23.3 23.3 26.6 26.7 27.8 26.7 Deductio n 7 12.9 12.4 17.4 16.3 18.3 16.7 14.2 13.3 22.2 22.2 8 11.0 11.0 18.2 18.2 20.6 20.6 19.2 19.2 17.8 14.4 Rigor 9 9.1 8.1 8.1 7.4 10.0 9.4 11.7 11.6 10.0 10.0 10 2.38 2.38 4.81 4.81 6.11 6.11 9.17 9.17 5.56 4.44 N Sample 210 of Student Teachers 270 of Student Teachers 180 of Student Teachers 120 of Student Teachers 90 of Student Teachers Information: CA: Correct Answer CR: Correct Reason Based on these results it can be concluded that the student teachers from 2013 to 2017 were able to answer correctly more than 50% at the level of visualization and analysis. In addition, the student teachers were able to answer only about 30% of the level of abstraction, 22% of the deduction level, and 11% of the rigor level. The results showed that the student teachers did not understand the definition well and did not classify well the various types of quadrilateral at the level of abstraction, deduction, and rigor. This result was a serious problem for student teachers as they will transfer knowledge to their students in elementary, junior, and senior high schools after they have completed their study at the State Islamic University of Riau Province. The observations during five years were conducted by detecting students' difficulties in learning through FGD (Focus Group Discussion) with six mathematics lecturers teaching Geometry. The FGD was conducted to discuss the researchers' findings of the difficulties of the student teachers in learning Geometry. From the results of the FGD, six lecturers agreed with the research findings that the student teachers had difficulties in learning geometry specifically in defining, connecting and classifying the quadrilateral types. From the FGD, the researchers offered a solution to make a media in the form of a module to help the student teachers to understand, define, and classify quadrilateral types. The module was very important to develop because it was based on the problems found during learning. The media in the form of geometry textbooks that the student teachers used did not help the student teachers achieve the learning objectives covering drawing conclusions about defining and classifying various types of the quadrilateral. The second stage, the design stage, was to design module to be attractive, to determine the competencies to be achieved, and to determine the problems related to the concept Risnawati, Andrian, Azmi, Amir & Nurdin 547 International Journal of Instruction, July 2019 ● Vol.12, No.3 of defining and classifying quadrilateral. In the design stage, a module design was produced consisting of three parts, namely introduction, content, and closing. The third stage is the development stage. The researcher developed the module validity or feasibility assessment sheets, practicality sheets, questionnaires and test to assess the effectiveness of the module. The validity or feasibility assessment module was used to identify the level of validity and feasibility of the module developed. Practicality assessment sheets were used to see how far the module was practically developed in aspects of being easy to use, easy to understand, interesting to use in learning and able to accelerate understanding in Geometry learning. The questionnaire was developed to obtain information about student teachers' opinions about the practicality of the module being developed. The test aimed to check the student teachers' mathematical reasoning ability after participating in learning using the module. The fourth stage is the implementation stage. The implementation stage was the stage of testing the module. The implementation stage aimed to identify the level of validity of the module. This validation was carried out by the experts on measurement, the experts on mathematical material and the experts on mathematics learning media as well as the practitioners (the lecturers). The validated aspects included module feasibility in terms of material and media design. Material validation and media design aimed to test the feasibility of the content, feasibility of presentation, language assessment, and learning assessment. Validation of student response questionnaires aimed to check the questionnaire format, the language used, and the questionnaire statement to assess the module. Test validation aimed to check the suitability of the problem with mathematical reasoning ability. The next stage of the implementation is testing the practicality level of the module. Practicality test aimed to see the use of a module that were practical to use, easy to understand, interesting to use, useful and able to accelerate the student teachers in understanding geometry. Practical tests were carried out through the assessment of experts, practitioners and teacher candidates. The module effectiveness trial aimed to check the differences in mathematical reasoning skills between student teachers who took part in learning by using a quadrilateral definition and classification module with the students who did not use the module. The module effectiveness test on students' mathematical reasoning ability was done by giving treatments to one class and another class with the condition that both classes were homogeneous. Mathematical reasoning ability in two classes were compared based on the scores obtained at the end of the quadrilateral type learning. Fifth, the evaluate stage was the stage of evaluating the effectiveness of the module that had been developed. Description of Module The quadrilateral types definition and classification module consist of three parts, namely the introduction, content, and closing. The introductory section consists of cover, preface, table of contents, competency standards (achievement of graduate learning), the final ability of each stage of learning, checking the readiness of students regarding prerequisite material, and key answers. The material content section consists of various quadrilateral wide problem presentations that can be done using formulas, elaboration of the material along with the student activity sheets on the definition of 548 Development of a Definition Maps-Based Plane Geometry ... International Journal of Instruction, July 2019 ● Vol.12, No.3 various quadrilateral types, and an evaluation consisting of four issues regarding the classification of different types of quadrilateral, namely developing the ability to think logically, developing spatial intuition, instilling knowledge of further level of mathematics, and interpreting arguments mathematically. The closing section of the module consists of conclusions, exercises on mathematical reasoning, key answers to various problems, student assessment sheets, and reference lists. Assessment of Module Feasibility An assessment of the feasibility of the module was carried out to see how far the module developed was suitable for the mathematics student teachers. Feasibility of the module was the main point to be assessed. The feasibility of the module was assessed from the aspects of the material used in the module, the competencies expected to be mastered by the student teachers, and the feasibility of the language used to develop the module. The feasibility of the module was assessed by 3 experts (measurement experts, mathematics learning experts, learning media experts) and 4 practitioners (mathematics lecturers). The results of the expert assessment can be seen in Table 2. Table 2 Results of Module Feasibility Assessment Aspect Validated Expert Average Practitioner Average Total Average Criteria μ ЅD μ ЅD μ ЅD The module developed is in accordance with the problems that will be resolved. 3.67 0.58 4.00 0.00 3.83 0.29 Very Feasible The material developed in the module is in accordance with competencies taught 3.33 0.58 4.00 0.00 3.67 0.29 Very Feasible The material developed in the module is in accordance with the level of education 4.00 0.00 4.00 0.00 4.00 0.00 Very Feasible The module uses punctuation marks, command marks and clear question words 3.67 0.58 3.67 0.58 3.67 0.58 Very Feasible There are clear instructions on how to work on the test items on the module 3.67 0.58 3.67 0.58 3.67 0.58 Very Feasible Tables, pictures, graphs, maps are clearly presented in the module 3.67 0.58 3.00 0.00 3.33 0.29 Very Feasible The formulation of the sentence on the test items in the module is communicative 3.33 0.58 3.00 0.00 3.17 0.29 Feasible The module uses a standard language and easy to use 3.67 0.58 3.67 0.58 3.67 0.58 Very Feasible The module does not use words/expressions that give rise to multiple interpretations and causes the user to misinterpret 3.33 0.58 3.67 0.58 3.50 0.58 Very Feasible The module does not use the language area 4.00 0.00 4.00 0.00 4.00 0.00 Very Feasible Based on the assessment of experts and practitioners it was found that all aspects of the feasibility of the module were assessed with a feasible category (1 with a feasible category and 9 with a very feasible category). These results indicated that the experts and practitioners considered the module developed by the researchers was in the appropriate category to be used for mathematics student teachers. The experts and the practitioners assessed the module developed to improve the student teachers’ reasoning. Risnawati, Andrian, Azmi, Amir & Nurdin 549 International Journal of Instruction, July 2019 ● Vol.12, No.3 Aiken validity for the Student Teachers Questionnaire Content validity was assessed by three experts, namely two measurement experts and one mathematical learning expert. Content validity was used to see how far the items developed by the researchers in terms of material, design, and language were feasible. The assessment was to obtain information about the opinions of student teachers on the module developed. The results of Aiken validity can be seen in Table 3. Table 3 The Result of Aiken validity for the Student Teachers 

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Development of a Definition Maps-Based Plane Geometry Module to Improve the Student Teachers’ Mathematical Reasoning Ability

At is a pervasive assumption in recent analytical philosophy that knowledge can be defined as a modality representing a rational agent's true and consistent beliefs. Such views are based on rationality assumptions. One is that knowledge can only consist of true propositions. This way of speaking is sharply at odds with the way we speak about knowledge, for example, in computing, where a so-called knowledge base can be a database, that is, a set of data that has been collected and is thought to consist of true propositions, even though, realistically speaking, many of them might later be shown to be false or untenable. In this study, opposed to the truth-implying idealized sense of "knowledge" there is pos? tulated a pragmatic sense of the term in which knowledge is sometime defeated, or shown to be false as new data comes in.1 The idealized conception of knowledge has worked its way, through the developments of epistemic modal logic based on the abstract no? tion of possible worlds, into analytical philoso? phy. Possible worlds, introduced as a technical device in the work of Kripke (1963) on modal logic, dominated the vocabulary and methods of analytical philosophy from that point on. This device purported to provide philosophers with a powerful explanatory apparatus for explaining the notion of knowledge. Hintikka (1962) started by arguing that his epistemic modal logics represented what is meant by the concept of knowledge, but later shifted from a descriptive to a normative approach in which he argued that epistemic logic represents an idealized model of how a rational agent knows (Girle 2003: 121). Girle's comment (121) is whether such normative models are real enough or too ideal, suggesting that, through such idealization, philosophers may have been led rather uncritically down a path that has con? fused more than intelligently guided the study of everyday arguments, based on the notion of knowledge that philosophical analysis should to be able to analyze and understand as part of their methodology. This paper puts forward a contrast between this idealized model of knowledge and a pragmatic model. On the latter approach, the term "knowledge" is defined in terms of a search through a database that may be more or less complete. As this dynamic process continues, more and more propositions are collected, and may be verified and falsified. Two factors are shown to be very important in judging knowledge in this framework. One is the question of whether the database is com? plete, in the sense that all the true propositions are known. The other is the contrast between what is known and what is not known. On this

Introduction to Logic.

Citations

Are Some Modus Ponens Arguments Deductively Invalid

Profiles of Dialogue for Relevance

A reexamination of the canon of objectivity in American journalism

Development of a Definition Maps-Based Plane Geometry Module to Improve the Student Teachers’ Mathematical Reasoning Ability

Pragmatic and idealized models of knowledge and ignorance