Whilst we taking a tour through the world of formal logic and philosophical arguments, it’s worthwhile to clarify a few other terms and concepts related to arguments. Arguments can be formed from deductive reasoning and inductive reasoning. Deductive reasoning is often explained as working from a general point to a specific conclusion. In deductive reasoning a person works from the premises and moves towards a specific conclusion – the syllogism arguments in the previous chapter were examples of deductive reasoning.
Inductive reasoning is the opposite of deductive reasoning; it makes generalizations from specific observation. In inductive reasoning you try to notice a pattern and generate a theory or an explanation for phenomena. A simple example of inductive reasoning might be to realize that all the swans you have ever seen where white and therefore believe that all swans are white.
In deductive reasoning, if an argument is valid and the premises true, the conclusion of the argument is also indisputably true. However, in inductive reasoning the conclusion of an argument is only supported and not proven to be true. The white swan example is a rather famous case; it was once believed that all swans were white, but it was discovered that black swans exist in Australia & New Zealand.
Occasionally you might also hear the term ‘abductive’ reasoning. Abductive reasoning tries to form the simplest and most likely explanation from the evidence provided – it is often called ‘inference to the best explanation’. You can think of abductive reasoning like a crime scene investigator meticulously observing a crime scene and theorizing what happened and how. The crime scene investigator doesn’t know what happened and nor can they always rule out the possibility of an alternative explanation for the evidence they gather. However, they can look at the little details and form a highly plausible explanation for what occurred.
In abductive reasoning, true premises do not guarantee the conclusion. In fact, in terms of logic abductive reasoning is fallacious – it generates conclusions from evidence or premises that cannot truly prove said conclusion. However, abductive reasoning is useful because often evidence is lacking and we do not have enough information to generalize – we essentially have to make a calculated guess using what we know.