This chapter uses Malthus's Essay on the Principle of Population to provide a simple model of stagnation, which explains GDP per capita’s flat trend during the longest part of History. That model of Malthusian stagnation explains the constancy of standards of living as follows: during the longest part of History, each time a technological progress took place, this was followed by a rise in population size that annihilated any improvement in standards of living. As such, this chapter provides one possible representation of the stagnation regime. Criticisms of that theory of long-run stagnation by Marx, Weyland and others are also examined.

Judgments in acceptability judgment tasks are not uniform – because of the conditions involved, but also because of additional variation across participants and across items. Some of the variation is meaningful, some is noise. This chapter discusses both types of variation and provides recommendations on how to deal with them. We show how some of the interspeaker variation stems from micro-differences between grammars. Statistical procedures like distribution analysis or cluster analysis help in detecting such variation. The same procedures can be used to identify variation across items. Further, we outline how to reduce variation across and within items. In particular, we recommend keeping length and complexity of sentences constant as well as the accessibility of NP-antecedents. The rest of the chapter deals with variation stemming from extralinguistic sources. Beside individual differences related to performance factors, e.g. working memory, we discuss methodological artifacts like scale effects and non-cooperative behavior.

This concluding chapter pulls together the material of this book into a more synoptic account. We begin by clarifying the aims of our book, highlighting that our approach poses steep challenges but also offers important payoffs. We proceed by summarizing the findings presented in previous chapters, discussing the causality of scale effects and the dimensions along which scale matters. We then offer a tentative theoretical synthesis that ties together many of the themes introduced in previous chapters. Next, we evaluate the implications of scale for big topics like governance, democracy, and freedom, where we identify a series of recalcitrant trade-offs. These concern efficiency (preferences versus policies), political relationships (informal/personal versus formal/institutional), systems of rule (intensive versus extensive), models of popular rule (participatory versus competitive), power (individual versus collective), and freedom (where trade-offs are conditional on structural features of the landscape). In the final section, we discuss the relevance of scale for current policy debates, looking specifically at the effect of boundaries between polities, changes in electoral laws, levels of government in a polity, and suffrage rights.

There has been a prodigious level of interest in graphene over recent decades, and also in (the closely related) carbon nanotubes (CNTs). This has included quite a strong focus on their mechanical properties, with various claims in particular being made about high strength levels, which relate to their extremely fine scale. Since the scope for their usage in isolation is relatively limited, at least in terms of exploitation of high strength levels, a lot of attention has been directed towards the production and use of composite materials containing them as reinforcement. Unfortunately, most of the hopes originally expressed have not been fulfilled. In fact, the mechanical properties of such composites have in all cases been inferior to those of conventional carbon fibre composites. This is partly due to severe difficulties in manufacturing composites with relatively high levels of well-dispersed, well-aligned reinforcement. However, this is not the only problem, since many of the original expectations were based on incomplete understanding of the issues involved in defining the strength of a material, with particular reference to the role of toughness. These CNT-reinforced composites tend to have a low toughness, as a direct consequence of their very fine scale. In this chapter, the issue of scale-related effects is first addressed in general terms, followed by information about some specifics of using fine-scale reinforcement (particularly CNTs).