Taxonomising Theistic Arguments (Part 1)

This is a work in progress. Comments and feedback are welcomed.

Sabio, over at triangulations, recently did a post on taxonomies. Luke, over at commonsenseatheism, is trying to develop a taxonomy of worldviews. Biologists, apparently, have been at it for years. I want to add my voice to the growing chorus of taxonomy-fetishists by attempting a taxonomy of religious/theistic arguments.

In doing so, I am inspired by what I recently read in Graham Oppy's book Arguing About Gods. In the opening chapter, Oppy sets out ad-hoc taxonomy of theistic arguments. But he says:

I don't care how the arguments are grouped together; what really matters is that no arguments should be neglected.

Frankly, that kind of attitude baffles me. I love a well-developed system of classification, and I think it does make a great difference to how we approach and perceive the world. One of the more persuasive aspects of Darwin's theory of branching descent was how it fit the Linnaean taxonomic system.

Now, I have heard all the usual criticisms. It is said that taxonomies can be arbitrary; that they carve nature at its non-existent joints; that they turn a continuous reality into a discontinuous abstraction. The classic example of this comes from Jorge Luis Borges. His short story "The Analytical Language of John Wilkins", which is all about arbitrary classification, includes the following (fictional) extract from a Chinese encyclopaedia:

[I]t is stated that animals can be divided into the following classes: (a) belonging to the Emperor; (b) embalmed; (c) trained; (d) sucking pigs; (e) mermaids; (f) fabulous; (g) stray dogs; (h) included in this classification; (i) with the vigorous movements of madmen; (j) innumerable; (k) drawn with a very fine camel hair brush; (l) etcetera; (m) having just broken a large vase; (n) looking from a distance like flies.

I'm sure we can agree that this classification system is silly and paradoxical ("included in this classification" - wtf?). Therefore, all classification schemes are silly and paradoxical. Case closed, right?

No, of course not. The response to critics like Borges is not to abandon systems of classification, but to develop better ones. The reason is straightforward: they are all we have. I challenge anyone to come up with a way of viewing the world that does not rely on some sort of classification. I maintain it can't be done.

This is turning into a bit of a rant so I'd better get back on track.

Going back to Oppy for a moment, and to be fair to him, he does offer a pretty decent taxonomy of theistic arguments. He divides them into ontological, cosmological, teleological, minor evidential, moral and non-evidential (pragmatic e.g. Pascal's Wager). This is a fairly standard philosophical approach. I want to try something a little different.

As stated at the outset, this is a work in progress. I would like to see if people agree/disagree with my approach. Obviously, if you do agree or disagree, give reasons.

Anyway, I will to do two things in this post. First, I will consider the need for an organising principle for the taxonomy. Second, I will sketch my proposed taxonomy. To give the discussion some credibility and weight, I will use evolutionary "tree of life" taxonomies as a reference point.


1. Finding an Organising Principle: A Pilgrimage? 
All good taxonomies need an organising principle: some overarching cognitive goal that shapes and guides the process of classification. Bad taxonomies, like Borges's one, lack organising principles. To illustrate the point, consider the following (beautiful) diagram (you need to click on it to get the full effect):

This diagram is of the tree of life. The organising principle behind the tree is descent with modification. This is the idea that every organism is related by descent from a common ancestor. They look and behave differently because offspring can differ slightly from their parents (or parent!) and, given enough time, this process results in the huge diversity of life. The diversity and time is amply illustrated in the diagram.

The tree of life represents a journey through design space.* It starts with one parent organism at time T1, this parent has offspring at T2, they have offspring at T3 and so on. At each reproduction point, the offspring can spread through design space. What is meant by this is that although organisms vary along multiple dimensions (bone density, size of teeth, acuity of vision, sensitivity, brain mass etc.), and so occupy a vast swath of a multi-dimensional design space, they once started off in a localised, non-differentiated location (i.e. the last universal common ancestor or LUCA).

So to reiterate, the organising principle of the tree of life is "descent with modification". By fitting organisms (living and extinct) into the tree, we can represent life's journey through design space.

There is another important point to be made here: we can approach the tree in two directions. We could, of course, start at LUCA and work our way up through the madly divergent branches to the present day. Alternatively, we could, as Richard Dawkins does in his wonderful book The Ancestor's Tale, go on a pilgrimage back down the tree of life.

In other words, we  could start in the present day (at the tips of the branches) and wander back down to LUCA. As we do so, we rendezvous with our cousins (who start out on their own pilgrimage at the same time). Our first rendezvous is with our chimpanzee and bonobo brethren, our second is with the gorillas, and so on.

These two ideas -- the organising principle and the backwards pilgrimage -- are going to guide my approach to taxonomising theistic arguments.

2. A Journey Through Argument Space
The organising principle for my taxonomy of theistic arguments is going to be dialectical usefulness in journeying through argument-space. That's quite a mouthful, so let's unpack it and see what it means.

I am imagining groups of believers and non-believers having an argument over who has the right beliefs. Their argument takes place in a multi-dimensional argument-space. This "space" consists of different methods of argument (emotional, evidential, experiential, scientific, historical, and logical) and different types of argument (first cause, moral, design and so on).

 The goal of both sets of individuals is to convert the other set to their way of thinking. To achieve this goal, they cannot simply dive-in and use their favourite arguments. They have to figure out how best to sequence their arguments in order to convince the other side.

The best sequence of arguments, is the one that achieves the most common ground between the opposing sides. We will rendezvous on different common ground with different types of believers. If we can get the participants to use the same methods, and to focus on the same arguments, at the same time, we will achieve partial success. If we can get them to agree on conclusions, we will achieve total success.

This is what I mean by "dialectical usefulness in journeying through argument-space".

I hope you can begin to see how this is similar to Dawkins's backward pilgrimage: Dawkins envisaged all the currently existing species setting out on a journey to LUCA; I am envisaging all current believers and non-believers setting out on a journey to a common ground (yet to be defined).

There are two crucial differences between my journey and Dawkins's journey. First, Dawkins's journey has a temporal dimension: we are not just journeying through design space, we are journeying through time. This means that the branches on the tree of life can only ever grow in one direction: upwards towards the future, not downwards toward the past. I suggest we ditch this temporal dimension when considering argument-space. This means that the tree we ultimately draw will have offshoots and dead ends that need to be traversed.**

Second, in Dawkins's journey, we rendezvous with those we are most closely related to first and those we are least closely related to last. I suggest that the opposite is true in argument-space: to find the most useful path is to find a way to rendezvous with those most distant from your position first.

This may seem counterintuitive but I maintain it is correct because you might not know who you are arguing with. So, imagine three different people: A is a non-believing, scientific rationalist; B is a believing scientific rationalist; and C is a believing anti-scientific fideist. Now let's approach an argument from the perspective of A (I do this because it is my own perspective).

A does not know whether he is arguing with B or C. If he was arguing with B, things would be relatively easy: they would agree on methods for testing and confirming their respective beliefs, and they could focus on the available evidence and on particular arguments (cosmological perhaps). If he was arguing with C, things would be more difficult because they would not have an agreed-upon method for assessing their relative beliefs. It seems clear that if A wants to have a successful argument, he must assuming he is arguing with C. In other words, he needs to start by showing why emotional convictions are not a sound basis for beliefs and then try to develop a common epistemology.


Okay, that's enough for now. In the next part of the series, I will try to offer a more detailed elaboration of the taxonomy of arguments that follows from my organising principle. Before that, I would love to get feedback back from any of the (20?) people who read this blog. Do you think this approach is useful? What snags might it face?


*An abstract representation of the possible ways in which an organism can vary.


**The tree of life also has these, but as we journey back in time we only ever find the ancestors of species that went down these dead ends, we do not journey down them ourselves. In argument space we may need to go down these dead ends in order to rescue our fellow travelers.