Professor Fisher on suppositions

I first support Alec Fisher's thesis that premises and conclusions in arguments can be unasserted first by arguing in its favor that only it preserves our intuition that it is at least possible that two arguments share the same premises and the same conclusion although not everything that is asserted in the one is also asserted in the other and second by answering two objections that might be raised against it. I then draw from Professor Fisher's thesis the consequence that in suppositional arguments the falsity (or unacceptability) of a supposition does not tell unfavorably in the evaluation of the argument, because the falsity (or unacceptability) of a (nonredundant) premise counts against an argument if and only if that premise is asserted. Finally, I observe that, despite the fact that they are neither expressed nor even alluded to, implicit assumptions in arguments are always asserted, unless the conclusion, but none of the explicit premisses, is unasserted. Hence, apart from an exceptional case of the kind just mentioned, the falsity (or unacceptability) of implicit assumptions always counts against an argument.I am indebted to Thomas E. Gilbert and Alec Fisher for their criticisms of an earlier draft of this paper.     

Deduction from Uncertain Premises

We investigate how the perceived uncertainty of a conditional affects a person's choice of conclusion. We use a novel procedure to introduce uncertainty by manipulating the conditional probability of the consequent given the antecedent. In Experiment 1, we show first that subjects reduce their choice of valid conclusions when a conditional is followed by an additional premise that makes the major premise uncertain. In this we replicate Byrne (1989). These subjects choose, instead, a qualified conclusion expressing uncertainty. If subjects are given a third statement that qualifies the likelihood of the additional premise, then the uncertainty of the conclusions they choose is systematically related to the suggested uncertainty. Experiment 2 confirms these observations in problems that omit the additional premise and qualify the first premise directly. Experiment 3 shows that the qualifying statement also affects the perceived probability of the consequent given the antecedent of the conditional. Experiment 4 investigates the effect of suggested uncertainty on the fallacies and shows that increases in uncertainty reduce the number of certain conclusions that are chosen while affirming the consequent but have no effect on denying the antecedent. We discuss our results in terms of rule theories and mental models and conclude that the latter give the most natural account of our results.     

Reasoning from uncertain premises: Effects of expertise and conversational context

Four experiments investigated uncertainty about a premise in a deductive argument as a function of the expertise of the speaker and of the conversational context. The procedure mimicked everyday reasoning in that participants were not told that the premises were to be treated as certain. The results showed that the perceived likelihood of a conclusion was greater when the major or the minor premise was uttered by an expert rather than a novice (Experiment 1). The results also showed that uncertainty about the conclusion was higher when the major premise was uttered by a novice and an alternative premise by an expert, compared to when the major premise was uttered by an expert and the alternative by a novice (Experiment 2). Similarly, the believability of a conclusion was considerably lower when the minor premise was uttered by a novice and denied by an expert, as opposed to when an expert uttered the minor premise and a novice denied it (Experiment 3). Experiment 4 showed that the nature of the uncertainty induced by a denial of the minor premise depended on whether or not the context was a conversation. These results pose difficult problems for current theories of reasoning, as current theories are based on the results of experiments in which the premises are treated as certain. Our discussion of the results emphasises the importance of pragmatics in reasoning, namely, the role of general knowledge about the world in assessing the probability of a premise uttered by an expert or a novice and the role of interpretations of the premise based on pragmatic inferences in revising these initial probabilities.     

Strategies during complex conditional inferences

In certain contexts reasoners reject instances of the valid Modus Ponens and Modus Tollens inference form in conditional arguments. Byrne (1989) observed this suppression effect when a conditional premise is accompanied by a conditional containing an additional requirement. In an earlier study, Rumain, Connell, and Braine (1983) observed suppression of the invalid inferences “the denial of the antecedent” and “the affirmation of the consequent” when a conditional premise is accompanied by a conditional containing an alternative requirement. Here we present three experiments showing that the results of Byrne (1989) and Rumain et al. (1983) are influenced by the answer procedure. When reasoners have to evaluate answer alternatives that only deal with the inferences that can be made with respect to the first conditional, then suppression is observed (Experiment 1). However, when reasoners are also given answer alternatives about the second conditional (Experiment 2) no suppression is observed. Moreover, contrary to the hypothesis of Byrne (1989), at least some of the reasoners do not combine the information of the two conditionals and do not give a conclusion based on the combined premise. Instead, we hypothesise that some of the reasoners have reasoned in two stages. In the first stage, they form a putative conclusion on the basis of the first conditional and the categorical premise, and in the second stage, they amend the putative conclusion in the light of the information in the second premise. This hypothesis was confirmed in Experiment 3. Finally, the results are discussed with respect to the mental model theory and reasoning research in general.     

A Probabilistic Interpretation of llIf-Then

This study proposes that subjects interpret thematic conditionals ('if p then q ') probabilistically in solving conditional reasoning problems. Experiment 1 found that subjects' correct responses increased with the perceived probability of q , given p for each of the four forms of conditional arguments: modus ponens (MP), modus tollens (MT), denial of the antecedent (DA), and affirmation of the consequent (AC). Experiment 2 ruled out two alternative explanations based on the comprehensibility of conditionals and on subjects interpreting conditionals as biconditionals. In Experiment 3, subjects solved two types of problems: (a) complete probabilistic problems, such as 'If p then q ; knowing p ; how probable is q ?', and (b) reduced probabilistic problems, such as 'Knowing p ; how probable is q ?' Two sources of information that determine the observable reasoning responses are identified. One source of information is based on one's general knowledge, and another is based on taking all premises into account.     

Inductive Reasoning in Alzheimer''s Disease

We evaluated knowledge of basic level and superordinate semantic relations and the role of cognitive resources during inductive reasoning in probable Alzheimer's disease (AD). Nineteen mildly demented AD patients and 17 healthy control subjects judged the truthfulness of arguments with a premise and a conclusion that contain familiar concepts coupled with "blank" predicates, such as "Spiders contain phosphatidylcholine; therefore all insects contain phosphatidylcholine." Like healthy control subjects, AD patients were relatively insensitive to the typicality of the premise category when judging the strength of arguments with a conclusion containing a basic-level concept, but were relatively sensitive to typicality during judgments of arguments containing a superordinate in the conclusion. Moreover, AD patients resembled control subjects in judging arguments with an immediate superordinate in the conclusion compared to arguments with a distant superordinate. AD patients differed from control subjects because they could not take advantage of two premises in an argument containing basic-level concepts. We conclude that semantic knowledge is sufficiently preserved in AD to support inductive reasoning, but that limited cognitive resources may interfere with AD patients' ability to consider the entire spectrum of information available during semantic challenges.     

When forewarning backfires: Paradoxical effects of elaborating social feedback on entrapment in a losing course of action

Entrapment occurs if people persist with losing courses of action. In two experiments, we show how elaborating social feedback (i.e., premature praise or forewarning regarding the chosen course of action) can have paradoxical effects on entrapment. The participants acted as head of a translation department and had to choose one out of four possible translation strategies for their employees. After choosing, they read four arguments (presumably written by former participants) which were either all in favor of the strategy chosen, all against it, or mixed. Half of the participants only read these arguments, whereas the other half elaborated on them by providing written comments (Experiment 1). The results showed that elaborating on other persons' arguments led to stronger entrapment, independently of whether the arguments were positive or negative. This pattern was due to biased argument processing: Whereas confirming thoughts were generated for positive arguments, negative arguments were refuted. Experiment 2 confirmed that this biased argument processing caused subsequent entrapment. These results indicate that elaborating any type of argument can lead to heightened entrapment and, hence, forewarning can backfire. Copyright © 2009 John Wiley & Sons, Ltd.     

Conditionals,Context, and the Suppression Effect

Modus ponens is the argument from premises of the form If A, then B and A to the conclusion B (e.g., from If it rained, Alicia got wet and It rained to Alicia got wet). Nearly all participants agree that the modus ponens conclusion logically follows when the argument appears in this Basic form. However, adding a further premise (e.g., If she forgot her umbrella, Alicia got wet) can lower participants’ rate of agreement—an effect called suppression. We propose a theory of suppression that draws on contemporary ideas about conditional sentences in linguistics and philosophy. Semantically, the theory assumes that people interpret an indicative conditional as a context‐sensitive strict conditional: true if and only if its consequent is true in each of a contextually determined set of situations in which its antecedent is true. Pragmatically, the theory claims that context changes in response to new assertions, including new conditional premises. Thus, the conclusion of a modus ponens argument may no longer be accepted in the changed context. Psychologically, the theory describes people as capable of reasoning about broad classes of possible situations, ordered by typicality, without having to reason about individual possible worlds. The theory accounts for the main suppression phenomena, and it generates some novel predictions that new experiments confirm.     

Logic, beliefs, and instruction: a test of the default interventionist account of belief bias

According to dual-process accounts of thinking, belief-based responses on reasoning tasks are generated as default but can be intervened upon in favor of logical responding, given sufficient time, effort, or cognitive resource. In this article, we present the results of 5 experiments in which participants were instructed to evaluate the conclusions of logical arguments on the basis of either their logical validity or their believability. Contrary to the predictions arising from these accounts, the logical status of the presented conclusion had a greater impact on judgments concerning its believability than did the believability of the conclusion on judgments about whether it followed logically. This finding was observed when instructional set was presented as a between-participants factor (Experiment 1), when instruction was indicated prior to problem presentation by a cue (Experiment 2), and when the cue appeared simultaneously with conclusion presentation (Experiments 3 and 4). The finding also extended to a range of simple and more complex argument forms (Experiment 5). In these latter experiments, belief-based judgments took significantly longer than those made under logical instructions. We discuss the implications of these findings for default interventionist accounts of belief bias.     

Effects of order of presentation on conditional reasoning

ABSTRACT

The main goal of this research is to study whether or not the order of presentation of the premises in a logical argument form, such as a conditional reasoning task, could affect the processing time of premises and conclusion and the conclusions that participants accept as valid in an evaluation task. One experiment is reported in which participants are asked to evaluate computer-presented conditionals. Half of the problems were presented in traditional order (“if p then q, p, therefore q”) and half in inverse order (“p, if p then q, therefore q”). The experiment showed that there was an order effect in processing the premises and conclusion: participants took longer to read the premises in traditional order than in inverse order, but they took longer to read the conclusion in inverse order than in traditional order. The finding is discussed with respect to the main theories of conditional reasoning.     

The influence of clause order,congruency, and probability on the processing of conditionals

Conditional information can be equally asserted in the forms if p, then q (e.g., “if I am ill, I will miss work tomorrow”) and q, if p (e.g., “I will miss work tomorrow, if I am ill”). While this type of clause order manipulation has previously been found to have no influence on the ultimate conclusions participants draw from conditional rules, we used self-paced reading to examine how it affects the real time incremental processing of everyday conditional statements. Experiment 1 revealed that clause order interacts with presuppositional congruency as readers hypothetically represent counterfactual statements. When if p, then q counterfactuals contained a presupposition that was incongruent with prior context, these statements took longer to read than when the presupposition was congruent, but for q, if p conditionals there was no such congruency effect. Experiment 2 revealed that reading times were influenced by the subjective probability of an indicative conditional regardless of clause order, with a penalty observed for low-probability statements relative to high-probability statements in both conditional clause orders. These data reveal a dissociation whereby clause order mediates the effect of suppositional congruency on reading times, but does not mediate the effect of subjective probability.     

Evaluating arguments during instigations of defence motivation and accuracy motivation

When people evaluate the strength of an argument, their motivations are likely to influence the evaluation. However, few studies have specifically investigated the influences of motivational factors on argument evaluation. This study examined the effects of defence and accuracy motivations on argument evaluation. According to the compatibility between the advocated positions of arguments and participants' prior beliefs and the objective strength of arguments, participants evaluated four types of arguments: compatible‐strong, compatible‐weak, incompatible‐strong, and incompatible‐weak arguments. Experiment 1 revealed that participants possessing a high defence motivation rated compatible‐weak arguments as stronger and incompatible‐strong ones as weaker than participants possessing a low defence motivation. However, the strength ratings between the high and low defence groups regarding both compatible‐strong and incompatible‐weak arguments were similar. Experiment 2 revealed that when participants possessed a high accuracy motivation, they rated compatible‐weak arguments as weaker and incompatible‐strong ones as stronger than when they possessed a low accuracy motivation. However, participants' ratings on both compatible‐strong and incompatible‐weak arguments were similar when comparing high and low accuracy conditions. The results suggest that defence and accuracy motivations are two major motives influencing argument evaluation. However, they primarily influence the evaluation results for compatible‐weak and incompatible‐strong arguments, but not for compatible‐strong and incompatible‐weak arguments.     

Properties of the diversity effect in category-based inductive reasoning

Four experiments investigated how people judge the plausibility of category-based arguments, focusing on the diversity effect, in which arguments with diverse premise categories are considered particularly strong. In Experiment 1 we show that priming people as to the nature of the blank property determines whether sensitivity to diversity is observed. In Experiment 2 we find that people's hypotheses about the nature of the blank property predict judgements of argument strength. In Experiment 3 we examine the effect of our priming methodology on people's tendency to bring knowledge about causality or similarity to bear when evaluating arguments, and in Experiment 4 we show that whether people's hypotheses about the nature of the blank property were causal predicted ratings of argument strength. Together these results suggest that diversity effects occur because diverse premises lead people to bring general features of the premise categories to mind. Although our findings are broadly consistent with Bayesian and Relevance-based approaches to category-based inductive reasoning, neither approach captures all of our findings.     

Deduction without awareness

We investigated whether two basic forms of deductive inference, Modus Ponens and Disjunctive Syllogism, occur automatically and without awareness. In Experiment 1, we used a priming paradigm with a set of conditional and disjunctive problems. For each trial, two premises were shown. The second premise was presented at a rate designed to be undetectable. After each problem, participants had to evaluate whether a newly-presented target number was odd or even. The target number matched or did not match a conclusion endorsed by the two previous premises. We found that when the target matched the conclusion of a Modus Ponens inference, the evaluation of the target number was reliably faster than baseline even when participants reported that they were not aware of the second premise. This priming effect did not occur for any other valid or invalid inference that we tested, including the Disjunctive Syllogism. In Experiment 2, we used a forced-choice paradigm in which we found that some participants were able to access some information on the second premise when their attention was explicitly directed to it. In Experiment 3, we showed that the priming effect for Modus Ponens was present also in subjects who could not access any information about P(2). In Experiment 4 we explored whether spatial relations (e.g., "a before b") or sentences with quantifiers (e.g., "all a with b") could generate a priming effect similar to the one observed for Modus Ponens. A priming effect could be found for Modus Ponens only, but not for the other relations tested. These findings show that the Modus Ponens inference, in contrast to other deductive inferences, can be carried out automatically and unconsciously. Furthermore, our findings suggest that critical deductive inference schemata can be included in the range of high-level cognitive activities that are carried out unconsciously.     

Bias in Conditional Inference: Implications for Mental Models and Mental Logic

Three experiments are reported in which subjects are given the opportunity to make any of the four inferences associated with conditional statements: modus ponens (MP), denial of the antecedent (DA), affirmation of the consequent (AC), and modus tollens (MT). The primary purpose of the research was to establish the generality and robustness of polarity biases that may be occasioned by systematic rotation of negative components in the conditional rules. In Experiments 1 & 2, three forms of conditionals were used: “if (not) p then (not) q”, “(not) p only if (not) q” and “(not) q if (not) p”. Experiment 1 used a conclusion evaluation task, whereas Experiment 2 used a conclusion production task. In Experiment 3, thematic conditionals were presented with and without a preceding scenario.

The biases investigated were (a) affirmative premise bias—the tendency to draw more inferences from affirmative premises and (b) negative conclusion bias—the tendency to draw more inferences with negative conclusions. The suggestive evidence for affirmative premise bias in the literature was not supported: very little evidence was found for it in the current experiments. Robust findings of negative conclusion bias were, however, found across the three experiments, although the bias was mostly restricted to DA and MT inferences. This suggests that the bias is best regarded as a difficulty with double negation.

The results are discussed with respect to both the mental logic and mental model accounts of propositional reasoning. Neither theory as currently formulated can explain all of our findings, although a plausible revision of each is considered.     

条件推理中否定前件下信念偏差发生阶段的ERP研究

以日常生活中的条件推理语句为实验材料,采用大、小前提和结论依次呈现的“推断-判断”范式,利用事件相关电位(event-related brain potential, ERP)技术探讨了条件推理中否定前件下信念偏差效应的脑内时程动态变化。结果发现：在行为反应上,较信念促进,信念阻碍下的正确率更低反应时更长;在脑电上,两条件(信念阻碍和信念促进)诱发的ERP波形仅在大前提加工阶段出现明显的分离。这表明该推理下的信念偏差效应可能早在对大前提的语义表征阶段就已发生。     

Exposure to moral relativism compromises moral behavior

Across two studies we investigated the relationship between moral relativism versus absolutism and moral behavior. In Experiment 1, we found that participants who read a relativist argument for tolerating female genital mutilation were more likely to cheat to win an incentivized raffle than participants who read an absolutist argument against female genital mutilation, or those in a control condition. In Experiment 2, participants who read a definition of morality phrased in absolutist terms expressed less willingness to engage in petty theft than those who read a definition of morality phrased in relativist terms, or those in a control condition. Experiment 2 also provided evidence that effects were not due to absolutist arguments signaling that fewer behaviors are morally permissible, nor to relativist arguments defending more disagreeable moral positions. Rather, the content of the philosophical positions themselves—the fact that relativism describes morality as subjective and culturally-historically contingent, whereas absolutism describes morality as objective and universal—makes individuals more likely to engage in immoral behaviors when exposed to moral relativism compared to moral absolutism.     

The macrostructure of informal arguments: A proposed model and analysis

Theories of informal reasoning and critical thinking often maintain that everyday, informal arguments can be classified into types based on the specific organization that the premises or reasons enter into in their support for the conclusion (Snoeck Henkemans, 2000; Vorobej, 1995b). Three general types are identified: convergent, coordinately linked, and subordinately linked arguments. There has been no empirical research, however, to determine whether these structural distinctions have any psychological reality. In the first two of four experiments, college students were presented with premise pairs from larger, informal arguments and were asked to judge the nature of the relationship between the premises in a pair. The judgments involved applying “tests” of linkage, subordination, and so on, that have been proposed in the theoretical literature on argument analysis (e.g., Walton, 1996a; Yanal, 1991). Results suggest that adults can effectively distinguish between linked (interdependent) and convergent relationships and can further distinguish between interdependencies that are full and those that are merely partial. Adults also distinguished between subordinate and nonsubordinate relations. Experiments 3 and 4 provide evidence that adults make use of information about argument structure in evaluating argument strength and in categorizing arguments. Experiment 4 further suggests that facility with macrostructure is only modestly related to deductive reasoning competence. Findings are framed in terms of a speculative account of how argument structure is identified and mentally represented.     

条件推理的语义关系表达形式效应

作者用以大学生为被试的实验考察, 基本条件句语义关系表达形式(充分关系、必要关系和析取关系表达形式)和作为心理模型外显建构的可能性判断任务对条件推理的可能影响。实验结果发现, 条件推理的语义关系表达形式效应显著, 条件句语义关系表达形式对被试条件推理有显著的影响, 条件推理成绩随条件句语义关系表达的外显程度增加而增加; 被试在可能性判断任务中对条件句所含心理模型的外显建构并没有明显改善条件推理的成绩; 在有可能性判断任务条件下, 被试外显心理模型建构的成绩变化模式并不能一致地预测条件推理成绩的变化模式。这些结果说明, 人们的条件推理可能并不是完全基于心理模型建构, 而是还受对条件句前后件之间语义关系理解的影响; 条件句表达形式中语义关系的外显内隐模式影响对条件句语义关系的知觉理解难易, 从而影响相应条件推理的成绩。     

The Selective Laziness of Reasoning

Reasoning research suggests that people use more stringent criteria when they evaluate others' arguments than when they produce arguments themselves. To demonstrate this “selective laziness,” we used a choice blindness manipulation. In two experiments, participants had to produce a series of arguments in response to reasoning problems, and they were then asked to evaluate other people's arguments about the same problems. Unknown to the participants, in one of the trials, they were presented with their own argument as if it was someone else's. Among those participants who accepted the manipulation and thus thought they were evaluating someone else's argument, more than half (56% and 58%) rejected the arguments that were in fact their own. Moreover, participants were more likely to reject their own arguments for invalid than for valid answers. This demonstrates that people are more critical of other people's arguments than of their own, without being overly critical: They are better able to tell valid from invalid arguments when the arguments are someone else's rather than their own.