Debate 101

I've been practicing being a mathematician (of sorts) of late. I've also been thinking about explaining why I think what I think. And why I believe CNN about riots in Toledo and not e-mail forwards about kidney stealing gangs in New Orleans.

A core idea I have been thinking about is that my ideas tend to be the results of chains of thought.

For example, when CNN reports that a curfew has been announced after disturbances following a neo-NAZI rally, there is a train of beliefs that leads me to believe this to be credible news.

- I believe that Toledo exists. I have friends who claim to live there. I have many people who talk about living there. I've driven through it.
- I believe neo-Nazis exist and stage rallies.
- I believe people tend to get violent rather quickly, especially in emotionally heated topics.
- I believe that curfews are a likely way for city authorities to try and restore order.

So even without CNN reporting on the incident, the incident fits into my world view. It helps, of course, that I believe that CNN is a news reporting agency and tends to accurately (if with bias) report news.

Let's sum up this set of beliefs as A, and represent the conclusions they lead to as B. We can represent this as

A-->B

(Sorry, couldn't resist putting in a bit of math; there's plenty more coming. But I'm trying to make in comprehensible.)

Now someone might propose reality A'. For example, neo-Nazis don't exist; the protestors are really government agents promoting a policy of capitalistic exploitation over the masses. A' would not lead someone to believe CNN when CNN reported riots in Toledo. And there might be separate proposals A'', A''', and such, each leading to a different interpretation of the CNN report.

Now in reality, these beliefs chain together:

(A) I believe my parents so
(B) I believe that cars are dangerous so
(C) I believe that lying down on the traffic lanes on a freeway is dangerous so
(D) I believe that people who do so are either insane, reckless, and/or stupid.

So we have

A-->B-->C--D.

In reality, we usually have more than one A for each B, more than one B for each C, and such. That is, we have something like

(A.1 + A.2 + A.3)-->B.1.
(A.1 + A.4 + A.5)-->B.2.
(B.1 + B.2)-->C.1.
and so on

Now the question that often interests me is this: How firm is belief D? In other words, how much of the logic and argumentation has to be wrong to make argument D' true instead? The tricky part is that often an argument A.1 will support B.1 or B.1', but not B.1''.

For example, a genetic similarities between species support the idea of evolution (B.1). They also can support the idea of a common designer (B.1'). They don't tend to support the idea of many separate creatures coming into spontaneous existence (B.1''). (Don't laugh; we're simply too conditioned to expect genetic similarities to easily consider the implications if they didn't exist.)

Those of you who love logic probably see lots of ways this line of thought can be used in persuasion. I'm afraid I probably lost many people, though, on the weird math symbols. Well, not very weird. I just don't have that many symbols available in plain text. But here's a quick conclusion:

It is generally useless to try and convince someone of a logical consequence (D) if they do not share the beliefs (C) that lead to that consequence. For example, try arguing against abortion with the belief that life begins at birth. (Note that the beginning of life is also a logical consequence of other beliefs.)