I'd like to have an argument please

People believe a lot of odd things. Donald Trump is the greatest President of all time; coal is good for humanity; I can loose weight with just 6 minutes exercise per day; the Queensland Reds will win the Super Rugby grand final.

And there are many reasons why we might hold these beliefs. I saw it on Fox News; I read about it in a book; I heard it from a man with PhD wearing a lab coat; believing it makes me feel good. Psychologists, sociologists, and cognitive scientists can furnish us with a range of explanations about why we believe such things - belief preservation, motivated reasoning, the halo effect, self delusion.

But a much more interesting question is whether we should believe them.

Now some of the reasons we should believe certain things are the same reason we do believe them - experts typically know more about their domain than we do, believing certain things might help me reach my goals - but the simplest reason we should believe something is just because it is true.

Of course, how we can know that certain things are true turns out to be pretty tricky. We could know something is true because we saw it but our perceptions are fallable. We could rely on our memory of something but memories can be faulty. We rely on the testimony of others but they could deceive us. We could make something true by definition but that seems pretty empty.

One very simple way of know something is true however, is by reasoning our way to it. And for that we need argument.

An argument is simply a connected series of statements used to establish the truth of some other statement. You hear, see, and use arguments everyday - scientific explainations, legal justifications, and advertisements are all arguments. Any time you come across the word because, you are dealing with an argument.

Arguments consist of truth bearing statements called propositions. These are any statement that could be true or false about the world we live in - "Over 90% of climate scientists believe in anthropogenic climate change" (objectively true), "New York City is the capital of New York state" (stipulatively false), "it will rain tomorrow" (unknowable today), "Salted peanut butter ice-cream is better than pistachio lime flavour" (subjectively true).

We can weave these propositions together to establish the truth of some other proposition through a process of inference:

  1. Either Fred ate my chocolate or Bob did.
  2. Bob is lactose intolerant.
  3. Therefore Fred ate it.

If propositions #1 & #2 in this admittedly odd and trival example are true, then it is high likely that proposition #3 is also true. Of course, Bob could have been happy to suffer an afternoon on the loo the still have eaten my chocolate just to piss me off and to set up Fred but given the relative implausibility of that scenario, I would be justified in infering that #3 is true from #1 & #2 being true.

Now not all arguments are good ones in that they allow us to infer from the supporting claims to the conclusion. If there is no relevence between the claims, and if the supporting claims being true have no bearing on the conclusion being true, then we have a bad argument - in this case, a non sequitor.

So that's it. An argument is just a connected series of statements used to establish the truth of some other statement. Arguments are everywhere, explaining things or justifying them. Arguments help us know the truth of particular claims about the world and what makes them so useful compared with other ways of truth-knowing is that we can know the truth of a conclusion without ever having experienced it before.

So how do we work out which arguments are good ones and which are bad? That's a story for another week.

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Dave Kinkead

G'day, I'm Dave!

I work at the intersection of philosophy and technology. I'm a computational philosopher at the University of Queensland where I teach critical thinking, research digital pedagogies, and manage the UQ Critical Thinking Project. When I'm not thinking about thinking, I'm working on becoming a millionaire ski bum.

So far I've nailed the ski bumming bit.