Terry and all,
I'm glad the references to Bob Horn's work struck you as important. I'm a great fan of his work. (He is on our Board of Governors too). But dealing with your central point: 

On 08/04/2010, at 11:51 PM, Terence Love wrote:

> The fundamental issue to be addressed in any kind of design (and often not
> addressed by graphic designers) is accurately predicting the behaviour of
> the outcome. For example, how does one know if a poster and a public health
> promotion program will achieve its aim of reducing smoking by 50%? Why did
> or didn't the design produce the right outcome? To ask these questions about
> behaviour is central to design as a profession and to development of
> suitable design methods, design processes and design education.

I'm not sure that this is necessarily the case in all aspects of design, nor even desirable, even in the case you mention. 
As you and many on the list will also know, I have been an advocate for evidence based design in my own field of information design. The reasons are simple enough. We have developed design methods for creating things like instructions for using a medicine, and if, following our methods, a pharmaceutical company creates instructions that people find difficult or impossible to use, then people can come to harm and even die. Everything about our design methods for this type of work is done with the intention of minimising any kind of disadvantage or harm to the people who have to use the designs.

And within very strict limits, we are able to 'predict' the outcome. I say within very strict limits because our research into these methods also shows that after a very short period of use—six months or so—there can be measurable deteriorations in the design's performance, in other words people start making mistakes in their use of the information, or they miss things. To use an analogy, its like watching a stable pattern at the edge of chaos slowly start to loose its stability and order before collapsing back into chaos. I would love to see some further research done on this phenomenon. I suspect there are at least half a dozen potential phds in this area.

But getting back to the idea that such methods are in some sense 'fundamental', I'd suggest there are many other methods and 'outcomes' to design. I think the case you mention can be looked at from many other valid points of view. 
> how does one know if a poster and a public health
> promotion program will achieve its aim of reducing smoking by 50%? 
First, I think there is a danger in being blind to the root metaphors involved in this approach. (The approach is widely described as 'social marketing'). The root metaphor is that of cause and effect: billiard balls bouncing off each other, so that the poster in this case has an effect on the person who sees it. 
If you are interested in an in-depth (100,000 word plus) critique of this approach, look at:
http://communication.org.au/publications/principles--amp--philosophy/Thinking-about-public-information-campaigns/104,30.html.

The second point I'd make is that even among the people who undertake such campaigns there is a recognition that such things do not have 'effects', even emotional ones. So, why do them? A potential reason for doing them can be discerned in a great deal of graphic design. I tend to think of much graphic design as concerned with the powerful biological  and social ritual of display. I wrote a brief blog about this at: http://blog.communication.org.au/?p=21

Put simply, governments and other organisations want us to see that they care about something, obviously in the hope that we too will care about it, or be shamed into doing something about it. But at the very least the ritual demonstrates that they care and have at least done something! And often the scale of the ritual is in inverse proportion to any real measurable outcome. It shows how much they *really* care. It's not all that complicated and nothing to do with cause and effect. But even if it is, there are some subtle 'effects'  

Think of mating rituals. Well done mating rituals get noticed by some potential mates, but not all potential mates end up mating with the displayer of that particular ritual. Does that make the ritual ineffective? Not necessarily. 

There are a few potential phd's in this area.

Anyway, the weekend and the footy call. Ritual, like metaphor, is everywhere!

David
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blog: www.communication.org.au/dsblog
web: http://www.communication.org.au