Central to any scientific endeavour are efforts to advance evidence and reasons in support of particular conclusions. Some conclusions are broad, ranging over all space and time; others are far narrower and may concern the attributes of a particular biological species, chemical element or geological feature. Some conclusions may depart from previous work, requiring some degree of revision to existing attitudes; other conclusions extend our understanding into new terrain. Attempts to understand scientific methods can be understood in terms of a desire to better articulate the kinds of arguments that scientists develop, the kinds of evidence that they appeal to and the reasons those methods and evidences are valued.

Very often the ability to comprehend and evaluate scientific arguments requires significant training in the relevant discipline. Gathering data and evidence in ways that are reliable is not always straightforward. Evaluating someone's analysis of the evidence and the plausibility of the conclusions she draws may require familiarity with sophisticated mathematics and statistics, computer modelling or the intricacies of technical apparatus that laypersons typically don't possess. Nevertheless, if we understand science very broadly as the collection of our best methods for investigating the world and reaching reliable beliefs about it, then we would all think more scientifically if we spent time developing basic critical thinking skills.

The need for more responsible argument evaluation can also be motivated by reflecting on the cognitive biases that we considered in Chapter 5. Given our natural tendencies to prefer evidence that fits with prior beliefs, for example, it becomes all the more important that we cultivate a habit of pausing to reflect on the reasons we have for holding certain opinions. Do we have good reasons for doubting anthropogenic climate change, or have we merely heard sceptical attitudes repeated sufficiently often that they have attained an inflated and false level of plausibility? An important step towards improving our critical thinking involves asking ourselves what reasons are being advanced in support of some claim, whether those reasons are themselves plausible and whether there are better ways of accounting for the conclusions being presented. Many arguments are advanced in opposition to mainstream sciences which are so patently unconvincing that basic critical thinking should be sufficient to expose their flaws. In this chapter, we'll review a variety of ideas that can help us all improve the way we assess arguments and debates.