It is not an exaggeration to say that Aristotle (384-322 BC) made modern civilization possible. He invented formal logic at a time where most of humanity could neither read nor write. If it wasn’t for Aristotle’s contribution to philosophy, we wouldn’t enjoy such a high standard of living nowadays.
In his book “Prior Analytics,” Aristotle outlined the method for drawing correct conclusions; his method is called syllogism or syllogistic reasoning.
A syllogism is a sequence of thoughts, ideas or statements that lead to an inescapable conclusion. Human intelligence can employ syllogisms (animals cannot, even the most intelligent) and, through programming, computers imitate what humans do naturally.
The three elements in Aristotle’s philosophy of logic
Syllogisms typically consist of three elements. In Aristotle’s works, the first element is called “major premise” because it is making a wide statement. For instance, “cats are carnivorous.”
The second element is called “minor premise” because it’s making a narrower statement. For example, “my pet is a cat.” I draw your attention to the fact that major and minor premises must share a common feature that enables a conclusion.
In our example, the conclusion is “my pet is carnivorous.” I can imitate Aristotle’s style and place the word “therefore” at the beginning: “Therefore, my pet is carnivorous.”
Categorical versus hypothetical syllogisms
When a syllogism is based on permanent characteristics, it’s called “categorical syllogism.” For instance, the major premise “all horses have four legs” and the minor premise “my pet is a horse,” lead to the categorical outcome “my pet has four legs.”
Syllogisms can also employ hypothetical premises. Let’s use the example, “when the weather is cold, there are fewer people on the beach” as major premise. The minor premise “today is a cold day,” leads to the outcome “today, there are fewer people on the beach.”
Modern philosophers have criticised Aristotelian syllogisms because of their rigidity, but that’s precisely their key strength. The whole point of syllogisms is to lead to conclusions that are either true or false.
Deviations from Aristotle’s logic lead to uncertainty. That’s far from ideal for making important decisions. If we employ as minor premise “today is a bit colder than yesterday,” you could conclude that “there are fewer people on the beach today than yesterday,” but you might be wrong.
If yesterday we had very hot weather, the fact that today is a bit colder might have little bearing on the number of people on the beach. As soon as you deviate from Aristotelian logic, your thinking accuracy will degrade.
Hypotheses in Aristotle’s philosophy of logic
The Scottish philosopher David Hume (1711-1776) attacked Aristotelian logic, arguing that it was incapable of generalising and making hypotheses. According to Hume, science requires a process of generalisation based on anecdotal observations.
Hume’s criticism is wrong because he is mixing hypotheses with conclusions. Aristotelian logic does not prevent you from making guesses and formulating theories, but it sets a standard for proving those.
Anecdotal observations do not carry scientific weight before they have been proven. Only then can Aristotelian premises be enunciated and solid conclusions drawn.
Hume may have favoured innovation and bold hypotheses, but those constitute only a preliminary step for employing the method devised by Aristotle twenty-three centuries earlier.
If you want to draw accurate conclusions, Aristotelian logic offers the best tools. Do not allow pointless criticisms to doubt a system of thought that has proven its high effectiveness over and over again.
If you want to make good decisions, you should do much better by following Aristotle’s recommendations. If you are interested in applying Aristotle’s ideas in everyday life, I recommend you my book “The philosophy of builders.”
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