Online research in philosophy

Four experiments are reported which investigated the types of truth tables that people associate with conditional sentences and the kinds of inferences that they will draw from them. The present studies differed from most previous ones in using different types of content in the conditionals, for example promises and warnings. It was found that the type of content had a strong and consistent effect on both truth tables and inferences. It is suggested that this is because in real life conditionals make probabilistic assertions, and that the strength of the probabilistic link is determined by the situation in which the conditional occurs. The implications of these findings for current theories of reasoning are considered and it is concluded that none of them is entirely satisfactory. It is suggested that more linguistically based theories may prove more successful.

In order to resolve the controversial discussion regarding content effects in deductive reasoning, we propose distinguishing between two inferential sources—an argument's form , and additional relations people associate with the argument's content —and analysing their interplay. Both sources are equally necessary in order to understand the role content plays in deductive reasoning. People make valid deductions from the content relations ( content competence ), but in thematic reasoning tasks, these deductions lead to the intriguing phenomenon known as content effects . Focusing on the interplay of both sources of inferences, the dual source distinction enables a novel class of predictions to be made, namely the correct mastery of the logical connectors ( form competence ) in tasks that require the individual to think about an argument's form in relation to its content. To illustrate the dual source approach and its implications, the selection task paradigm of conditional reasoning with a point of view is used in combination with two content domains: conditional promises with cheating and non-cheating perspectives and technical systems with causal perspectives. Experimental findings corroborate all three phenomena: content competence, content effects, and form competence. The dual source distinction is discussed with regard to current theories of reasoning.

In this paper I ponder the moral status of conditional threats, in particular the extent to which a threatened party would be permitted to use (lethal) defensive force. I first investigate a mugger case before turning briefly to the more complicated issue of national defence in the face of an invading army. One should not exaggerate the level of protection people under threat owe their conditioned killers simply because what is extorted is of little value. After all, either the conditional threat is willing to kill for something she has no claim on at all, or, if she has a just claim on it - or good reason to believe that she has - she is willing to kill to (re)acquire something of not much worth. In both cases the moral culpability of the conditional threat could be seen as reducing her claim on protection from harm.

The duty to keep promises has many aspects associated with deontological moral theories. The duty to keep promises is non-welfarist, in that the obligation to keep a promise need not be conditional on there being a net benefit from keeping the promise—indeed need not be conditional on there being at least someone who would benefit from its being kept. The duty to keep promises is more closely connected to autonomy than directly to welfare: agents have moral powers to give themselves certain obligations to others. And these moral powers, which enable promisors to create agent- relative obligations to promisees, correlate with rights the promisees acquire in the process, such as rights to waive the duty or insist on its performance. As a result of promises, promisees acquire (not only rights but also) a special status: the promisees are the ones wronged when promises to them that they have not waived are not kept. One more aspect of the duty to keep promises that is associated with deontological moral theories is that what actions the duty requires is at least partly backward-looking: what actions the duty requires depends on facts about the past, namely facts about what promises were made and then waived or not. This paper surveys these aspects of the duty to keep promises and then explores whether rule-consequentialism can be reconciled with them.

Causal conditional reasoning means reasoning from a conditional statement that refers to causal content. We argue that data from causal conditional reasoning tasks tell us something not only about how people interpret conditionals, but also about how they interpret causal relations. In particular, three basic principles of people's causal understanding emerge from previous studies: the modal principle, the exhaustive principle, and the equivalence principle. Restricted to the four classic conditional inferences—Modus Ponens, Modus Tollens, Denial of the Antecedent, and Affirmation of the Consequent—causal conditional reasoning data are only partially able to support these principles. We present three experiments that use concrete and abstract causal scenarios and combine inference tasks with a new type of task in which people reformulate a given causal situation. The results provide evidence for the proposed representational principles. Implications for theories of the na ve understanding of causality are discussed.

Deontic reasoning is thinking about whether actions are forbidden or allowed, obligatory or not obligatory. It is proposed that social norms, imposing constraints on individual actions, constitute the fundamental concept for the system of these four deontic modalities, and that people reason from such norms flexibly according to deontic core principles. Two experiments are presented, one on deontic conditional reasoning, the other on “pure” deontic reasoning. Both experiments demonstrate people's high deontic competence and confirm the proposed representational and inferential principles. Experiment 1 additionally shows small effects of the conditional formulations. These findings support the dual source approach (Beller & Spada, 2003) that distinguishes between domain-specific and domain-general inferences. Implications for other theories of deontic reasoning are discussed.

In two experiments, we investigated how people interpret and reason with realistic conditionals in the form of inducements (i.e., promises and threats) and advice (i.e., tips and warnings). We found that inducements and advice differed with respect to the degree to which the speaker was perceived to have (a) control over the consequent, (b) a stake in the outcome, and (c) an obligation to ensure that the outcome occurs. Inducements and advice also differed with respect to perceived sufficiency and necessity, as well as the degree to which these statements were perceived to be effective in changing the behaviour described in the antecedent of the conditional. Multiple regression analyses indicated that perceived control over the consequent, necessity, and sufficiency emerged as the best predictors of (a) the degree to which statements were perceived to be effective in changing the behaviour of the addressee, and (b) inference patterns on a conditional arguments task.

Recent research (e.g., Evans & Over, 2004) has provided support for the hypothesis that people evaluate the probability of conditional statements of the form if p then q as the conditional probability of q given p , P( q / p ). The present paper extends this approach to pragmatic conditionals in the form of inducements (i.e., promises and threats) and advice (i.e., tips and warnings). In so doing, we demonstrate a distinction between the truth status of these conditionals and their effectiveness as speech acts. Specifically, while probability judgements of the truth of conditional inducements and advice are highly correlated with estimates of P( q / p ), their perceived effectiveness in changing behaviour instead varies as a function of the conditional probability of q given not-p , P( q / ∼p ). Finally, we show that the conditional probability approach can be extended to predicting inference rates on a conditional reasoning task.