In a strict world of purely deductive reasoning, in which every proposition is tied to the next via an unassailable logical connection, many things are fallacies. Those things include aspects of the scientific method and much of informal reasoning. From a purely logical viewpoint it would seem that many or all informal arguments are just a mess of fallacious reasoning. However, it is possible to identify that some informal arguments are worse than others – so there is some disconnect here between a strictly logical notion of fallacy and its application to actual argument.
As I’ve suggested previously (and eventually will write a longer post about) much of this is due to the difference between formal proof (as used in formal logic and mathematics) and evidential reasoning. When reasoning with and about evidence, we are trying to evaluate which claims have merit. There is no fundamental guarantee of truth and our beliefs are provisional and open to change when new evidence is found.
The argumentum ad hominem and the appeal to authority are both common styles of argument that are used both fallaciously and non-fallaciously in arguments. Both styles of arguments pertain to issues of the credibility of claims made by a third person and so to make sense of when and how these arguments are valid, it is important to consider why we need evidential claims by other people.
Formal logic can be seen as a mechanism that is truth preserving i.e. it allows us to take propositions (or more complex entities) and operate on them using valid methods and ended up with propositions with predictable truth values. However, to function it needs some sort of established truths which could be axioms or ‘facts’ (claims which we know by some other means to be true). Necessarily establishing the truth of facts requires something more than formal logic and so we have science, philosophy, mathematics, peer-review, academic rigor, legal process and many other things which help us to varying degrees establish what is or isn’t true.
Much of what I just listed is social in nature – these are things that require multiple people to take part in for the process to work. They are also time consuming and cognitively challenging and open to challenge in terms of their reliability and veracity. This presents a challenge to us all in so far as it is not possible for any non-omniscient being to individually replicate all these processes by yourself. The more formal claims of mathematics are also not accessible to a single individual and arguably it has been many decades since a single individual could be fully conversant in all of the field of mathematics. Even an ambitious genius who hopes to verify all mathematical proofs up to, say, the mid-nineteenth century would still have to contend with the possibility that they have repeated an error in a proof thought to be true but which unknown to everyone contains an unobserved flaw.
In short – the edifice of human knowledge rests on the shaky foundations of that most dubious substance: other people and one’s own fallibility.
Credibility matters and so arguments that pertain to credibility matter. People can be wrong in multiple ways:
- Maliciously i.e. intentionally attempting to distort belief by
- Knowingly stating falsehoods – saying something is true which they no to be false
- By being misleading about relevance – providing evidence that appears to be relevant but is actually irrelevant
- By being misleading about process – knowingly suggesting evidence has greater weight or reliability than it actually does
- By bullshit – assert claims as if they were facts without any regard to whether they are true or not
- By suppression – knowingly hiding evidence or ignoring evidence or providing only part of the story
- Cherry picking – a specific form of suppression of evidence in which a person only uses the data that supports their claim
- By selective skepticism – by applying skepticism about either truth in general or a process in particular
- Self-deludely i.e. attempting to support a strongly held opinion despite the evidence
- All of the above in a less knowing way
- By being misled by cognitive biases
- By assuming they have more expertise in an area than they do
- Honest error i.e. the mistakes we all make because we make mistakes
- By being misled by cognitive biases
- By making errors in process
- By accidentally ignoring data
- By using an inappropriate process
- Incompetence i.e. the mistakes some people make because they aren’t actually very good at the thing they are supposed to be good at
- All of the above
So people: can’t reason with ’em, can’t reason without ’em.
Nobody can seriously cover all of human knowledge by themselves and yet we are faced with situations that require the integration of claims from multiple fields of knowledge if we are to make sound decisions. Take a policy decision like implementing a carbon tax: that requires an understanding of taxation policy (in which ever country you are), international trade agreements, micro- and macro-economics, resource economics specifically, PLUS all the fields of study in the area of climate change including physics, chemistry, climate science in general etc etc. Even if one brilliant polymath gets their head around all of these things and derives their conclusions (without making errors) this genius would still be stuck with the problem of how to convince everybody else that her conclusion was correct.
So we have no choice – if we are going to debate matters of real significance then, at some point, we have to consider what other people have claimed without re-doing all their leg work ourselves. Consequently, arguments are going to shift away from questions of physical evidence and to questions of credibility – i.e. who is making this claim and can they be trusted?
More in Part 2 later.