There was a state election in Victoria recently. As you’d expect we were getting a lot of political junk mail in our mailbox, including this postcard*:

Vote Green postcard

Actually, it is a bit unfair to call this “junk” mail, since it appears to be an first-rate piece of graphical communication – an excellent use of what Bob Horn calls visual language. It is presenting a serious argument, but in a cartoon format. Obviously the format makes the somewhat dull subject-matter (how the election system works, and why that means your vote for the Greens is not wasted) much more engaging.

It reminds me of another excellent argument cartoon, by Scott McCloud.

From a theoretical standpoint, the postcard is also interesting as an illustration of how the order of presentation of claims is generally not the same as the logical order among the claims.

What does this mean?

Well, the main point the card wants to make is that the claim, which apparently many believe, that

(1) A vote for the Greens is a wasted vote.

is wrong – i.e., it is objecting to that claim.

Now, if presentation order was the same as logical order, you’d expect the main objection to the claim – the thing which is “closest” to it, logically speaking – to be also closest on the page.

However, what we see next is, in simplified form:

(2) In the first count of ballot papers most often no one hits 50% first time.

But that isn’t actually the main objection to (1). On its own, it doesn’t seem to make any difference to (1).

The main objection is actually quite a bit further down – the claim we might paraphrase as

(3) A vote for the Greens has double the influence [of a vote for a major party].

The text in between (1) and (3) is actually subordinate to (3), which then refutes (1). And there is some logical complexity already in the material between (1) and (3).

It might be clearer if we lay this out in a diagram:

Vote Green Simple

Notice how, as step down the logical order, claim (1) is the last claim we reach – whereas in the order of presentation, it was the first thing mentioned after the contention at issue.

There’s one more complication here – the final claim,

A higher vote for the Greens sends a strong message.

This is another objection to the main contention, and so appears at the top level:

Vote Green Simple 2

This illustrates the relative strengths and weaknesses of argument maps versus other forms of presentation. When done really well, other forms, such as the cartoon postcard discussed here, can be more engaging, and can convey the gist of a complex argument quite effectively. However they generally present the logic in a quite convoluted order, which often makes it difficult to determine exactly what the argument is.

An argument map, by contrast, is rather spartan; it presents just the claims and their logical relationships. But it does this in a totally transparent and unambiguous way. If your concern is getting the argument exactly right – perhaps because you want to know, with great confidence, just how good it is – then the argument map format is the best one.

A lot more could be said about this argument. The maps here are just a simple “first pass” laying out of the argument. In particular, I haven’t made any mention of the various assumptions being made, and where they fit on the map. A topic, perhaps, for another entry.

* Reproduced without permission – though I figure this is OK since I’m helping spread the Green message