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Chater and Oaksford developed both computational- and algorithmic-level analyses of syllogistic reasoning, based on a probabilistic approach. The resulting model was called the probability heuristics model (PHM). This chapter first outlines PHM, then shows how it can account for the existing data, and compares it with alternative theories. Finally, it looks at the empirical results that have emerged since the model’s appearance and addresses some of the arguments that have been levelled against it. An important feature of PHM is that it extends directly to syllogisms involving generalized quantifiers such as most and few. The crucial feature of these syllogisms is that they cannot be explained logically, and hence they fall outside the scope of theories like mental logic and mental models that assume standard logic as their computational-level theory.

In this chapter, four subtests of the CART are described. All four are direct measures of the avoidance of miserly processing. The subtests are: the Reflection versus Intuition subtest; the Belief Bias in Syllogistic Reasoning subtest; the Ratio Bias subtest; and the Disjunctive Reasoning subtest. All of these subtests have heavy processing requirements despite varying substantially in their knowledge dependence. The history of each subtest is described, as well as a large study of each subtest in which correlations with cognitive ability and thinking dispositions are examined. Correlations among these subtests themselves are reported from several different studies.

It is clear that a wide range of situations exist that can potentially lead people to believe that they have experienced the paranormal when in fact they have not. The question regarding possible differences between believers and non-believers in the paranormal in terms of proneness to cognitive biases can now be answered rather more definitively than has been possible previously. Believers in the paranormal tend to be poorer at syllogistic reasoning, have a more distorted concept of randomness leading them to see meaning where there is none, are more susceptible to experiencing anomalous sensations and are, in certain circumstances, more suggestible. Memory biases in the accuracy of eyewitness testimony for ostensibly paranormal events have also often been reported, and evidence is beginning to accumulate that believers may be more prone to false memories.

This chapter examines judicial reasoning in France. In France, the long-established assumptions, still deeply rooted in the French legal mind, that only the legislature can make the law and that codes provide a self-contained and internally consistent body of legislation, have greatly contributed to the deductive model of legal reasoning which prevails in the French judicial method. In such a system, codes are deemed to provide the axioms and postulates from which conclusions are drawn. From this it follows that judicial decisions cannot, overtly at least, be the outcome of what the judge feels to be the best solution. They are primarily the result of applying a rule of law to an actual situation. However, the chapter shows how in practise judges has been able to introduce value judgement in their decisions despite the constraints of the system.

This chapter argues that Kant’s Critique of Pure Reason was meant to provide a new logic, a transcendental logic capable of moving beyond the merely analytic conclusions of syllogistic reasoning and capable of securing the claims reached by way of induction. For these reasons, Kant secured Bacon’s inductive practices. The choice of Bacon—father of the “New Science”—was, in fact, a case of subversive appropriation on Kant’s part and that what it announced, more than anything else, was his specific intention with respect to a redefinition of empirical science altogether.

Welcome to Camberwell, home of the Institute of Psychiatry at King’s College London. In many ways Camberwell is typical of inner-city London: built-up, busy, and ethnically very diverse. It’s also an area of considerable poverty. In the 2004 Index of Multiple Deprivation—a government-sponsored survey of living standards across England—Camberwell was ranked at 6,327 out of 32,482. This sounds alright until you know that the most deprived area is ranked number 1 and the least deprived number 32,482. (Parts of the Anfield area of inner-city north Liverpool were officially deemed the most deprived place in England in 2004; the village of Oakley in rural Hampshire took place number 32,482.) Pictured opposite is the area’s main shopping street. Follow it far enough and it’ll lead you to the Thames, but the wide expanse of the river seems a very long way from the run-down, traffic-clogged, and people-thronged streets of Camberwell. What effect—if any—does an urban environment like this have on paranoia? To find out, we asked fifteen volunteers with strongly paranoid thoughts to walk down the Camberwell Road from the Institute, buy a newspaper, and come back. Afterwards they were given a range of psychological tests. Finally, their test scores were compared to those of fifteen other people, again all with pronounced paranoia, who’d simply stayed at the Institute listening to a relaxation tape. Did making the trip down the Camberwell Road increase the volunteers’ level of paranoia? Absolutely. And given the stressful nature of the environment that didn’t come as a surprise. (As we saw in Chapter 3, there’s a well-established link between stress, particularly in urban environments, and mental illness.) More intriguing though were the results of one particular psychological test: the beads task. In the beads task, participants are presented with two glass jars. One contains 85 orange beads and 15 black beads; the other contains 85 black and 15 orange. The beads have been mixed up in the jars. The researcher conducting the test chooses one of the jars (without telling the participant), and moves them both out of view.