This chapter considers induction, deduction and abduction as methods of obtaining scientific knowledge. The introductory section again ends by highlighting that there is no single method, and refers to claims that scientific reasoning uses various heuristics or rules of thumb based on the specific approach and the background information we have, and that we should recognise that this can introduce various errors of reasoning: by being aware of the potential for making these errors, we are better able to guard against making them. The bulk of the chapter then looks at specific logical fallacies, using neuroscience examples to illustrate them. These include ad hoc reasoning; begging the question; confusing correlation for causation; confirmation and disconfirmation biases; false dichotomies; false metaphors; the appeal to authority, tradition and emotion; the mereological fallacy; the naturalistic fallacy; and straw man arguments.

Suicide is a leading cause of death for young people (variously defined as those aged up to 24-29 years) worldwide. Non-fatal self-harm, which we define as including all intentional acts of self-poisoning (e.g., intentional drug overdoses, ingestion of products not intended for human consumption) or self-injury (e.g., self-cutting) regardless of degree of suicidal intent or other types of motivation is more common. In this chapter, we do not distinguish between attempted suicide and non-fatal self-injury as there is a high degree of co-occurrence between the two behaviours, particularly in young people.

The final chapter considers the challenge of immigration in global context, and explores possible paths going forward. Immigration is taking place in a context of globalization and pressures for deglobalization, climate change, declining birth rates, and aging populations in many Western and non-Western countries, as well as lower trust. One group of extremists are placing intense pressures on national governments to completely close borders to immigrants, but other extremists insist that borders should be open. Authorities have to apply policies somewhere between these two extremes. As societies become increasingly diverse, authorities must also adopt policies for managing diversity. We have suggested that omniculturalism and the celebration of human commonalities, as well as increasing intergroup contact, represent promising avenues for meeting the contemporary challenge of immigration.

Thus far, we have largely considered technologies that are capable of changing persons’ mental states. However, today, a range of technologies are also being developed that can gain insight into the mental realms of others. One example is the measurement of brain activity, which has enabled researchers to make inferences about individual mental states and faculties. In particular, fMRI and EEG can measure brain activity in a way that allows for inferences about what a person remembers, recognises, thinks or feels. EEG has been used, for example, to identify concealed memories about a criminal offence; and fMRI has been used to reveal sexual orientation, political ideology or a person’s craving for cocaine. Recently, various research groups used neurotechnology together with emerging forms of artificial intelligence (AI) to decode mental content from brain activity, with some interesting first results. According to Brownsword, with the development of these kinds of “brain-reading” technologies, “researchers have a window into the brains and, possibly, into a deeper understanding of the mental lives of their participants”.

Suicide and suicide attempts ravage societies and are now considered a top priority on the Global Health Agenda. In Ghana, lack of systematic reporting and recording hamper genuine efforts to prevent the problem. Among the many factors militating against progress in this direction is the strong taboo associated with suicidal behaviours in general and the criminalisation of suicide attempts in particular [1].

Evidence is essential to suicide prevention. Delay until the evidence base is complete is not possible, so cautious advice must be given to policy makers on imperfect evidence. This means recognising uncertainty, including the risk that the advice may cause more harm than good. Evaluation during implementation is critical but frequently neglected. The UK has a system of nationwide statistics, supplemented by a National Confidential Inquiry into Suicide and Safety in Mental Health (NCISH) into all apparently suicidal deaths during or after mental health care. In addition, there are recently devised real-time statistics of suspicious deaths. There is a system of self-harm registers, independent of official systems. These systems have generated unusually good information on suicidal deaths and self-harm, leading to tangible improvements. However, like all evidence, it is still imperfect.

Men comprise the majority of those who die of suicide [1]. This pattern is often taken as an indication that suicide is a male behaviour and a male problem, and that men are naturally and perhaps inevitably more prone to suicide than women (see Canetto’s studies in 1992–3 and 2021 [2,3] and Kushner’s 1993 study [4] for critical analyses of this idea).

Suicide, however, is not always more common in men than in women when the data is examined over time, by country and within country by age groups. For example, as recently as 2012, men were less likely to die of suicide than women in China, Indonesia, Iraq and Pakistan [5]. These countries compose a major proportion of the global population, so their suicide patterns cannot be dismissed as minor exceptions. Also, currently, in some countries, men are less likely to die of suicide than women in certain age groups.

This chapter examines the psychological foundations of assimilation and multiculturalism. Assimilation is rooted in intergroup contact and similarity-attraction theories, which suggest that increased interaction and perceived commonality between immigrants and host societies foster trust, reduce prejudice, and facilitate integration. However, assimilation faces challenges such as societal resistance, biases, and the tension between maintaining cultural identity and adapting to the dominant society. In contrast, multiculturalism emphasizes the value of cultural diversity. It is grounded in the psychology of cultural identity, intellectual humility, and the belief that embracing one’s culture can promote acceptance of others. Despite its benefits, multiculturalism also faces challenges in balancing diversity with social cohesion and overcoming resistance from dominant groups. This chapter explores how these psychological principles inform both assimilation and multiculturalism, their impact on intergroup relations, and the complexities of integrating immigrants into diverse societies.