This is a textbook for the whole or a significant part of a particular kind of philosophy course. It’s for a course that has as a main goal learning how to do the exegetical task of analyzing or making explicit the arguments presented in a classical philosophical text. The volume has texts from across many of the special areas in academic philosophy, including the philosophy of religion, epistemology, the relationship between mind and body, freewill and determinism, and ethics. The texts represented for analysis come from Plato, St Anselm, Hume, Gilbert Ryle, and so on, up to John Searle and Paul Churchland. After a few chapters introducing argument analysis using examples from outside philosophy, for each of these texts Harrell asks and makes explicit the answer to the title question ‘What is the argument?’. Sometimes she also includes some evaluation comments on the analyzed argument. So a course this textbook might be suitable for is an introductory-level survey that emphasizes the analysis of philosophical arguments. It might also be useful for a critical thinking course of the kind offered by philosophy departments at many colleges and universities. One reason to question this use is the issue of skill transfer. A critical thinking course will often have as a main objective learning how to analyze arguments into their component parts. But the idea is that this skill should be applicable everywhere and not just in philosophy. What is the Argument? only considers philosophical texts. So will students using this as their main textbook in a general purpose critical thinking course be able and disposed to take these tools of argument analysis beyond philosophy? Fortunately there is evidence that the argument analysis skills acquired with only these examples will in fact transfer.^{Footnote 1}

A special feature of this textbook is its concentration on learning how to present the result of an argument analysis as an argument diagram or map. Many readers of this journal will be familiar with presenting an analyzed argument in what is sometimes called ‘standard format.’ This is an ordered list of statements, some being premises of the argument and at least one a conclusion. An argument diagram or map is a directed graph representation of an analyzed argument, with premise and conclusion statements as the vertices or nodes of the graph and support or inferential relationships as the directed arcs or edges. Here is a brief example showing the difference. In the Critique of Pure Reason, Kant says:

A standard format presentation of the argument here is:

1. (1) Changes are real

2. (2) Changes are possible only in time

3. ∴ (3) Time is something real

A diagram or map presentation (drawn using the online version of the Rationale argument diagramming program with colour removed^{Footnote 2}) is:

Is there any benefit to using the diagram over the standard list representation format for an argument, at least when it comes to learning how to make their important parts explicit? Unfortunately, what evidence there is says that, when time spent on learning argument analysis is controlled for, using argument diagrams is no better than the standard format, at least in the short term.^{Footnote 3} Of course, this allows for there being longer term beneficial effects from argument mapping. In addition, argument mapping is certainly more engaging and so are some of the tools for producing them than producing standard format analyses with a word processing program. This can have various beneficial effects, including students spending more time on learning.

How should What is the argument? be used as a course textbook? If the textbook under review has a good analysis of St Anselm’s ontological proof for the existence of God, for example, what is left for an instructor to do in the classroom when using that section of the volume? Here, it is good to think of how a symbolic logic textbook might be used in a course. If an introductory level logic textbook has a good explanation of how to use the EXIST ELIM rule, what might an instructor add? Sometimes it is useful for an instructor to re-explain what’s in the textbook. For this text, in cases where the author doesn’t comment on the quality of the argument she has extracted from a philosophy text, an instructor could also do this. But a much more important thing is doing supervised student practice, just as in a logic course. As there often is with a typical symbolic logic textbook, there are exercises to be done in the classroom and for homework. Indeed, what the research evidence shows is that lots and lots of sequenced and supervised practice is central to learning the skill of argument analysis and improving critical thinking capacities.^{Footnote 4} You won’t learn how to juggle or play the harmonica just by having someone else do this or lecture to you about how to do it.