The Four Types of Reason - Aristotle Topics - Parts I - XIII
In the Topics Aristotle says that he is laying out the nature of reasoning. He defines it generally as an argument in which when certain truths are set out others become manifest. He then gives four types of reasoning: Demonstration, dialectic, contentious, and mis-reasoning.
Demonstration is the highest form of reasoning with regards to its level of certainty because the truths with which is begins are "primary and true," or in other words are self-evident to all and cannot really be put into question. Dialectical reason does not begin with premises that are self-evident but those which may be generally regarded by many or most to be true. They still carry some weight to them, but may end up being wrong. Then there are contentious types of reasoning in which the premises set down may seem to be generally accepted on their face, but in reality are not, or even fallaciously misleading. Lastly, Aristotle mentions mis-reasoning, which is something like an error within reasoning in a specific technical science. The example he gives in an error within the workings of geometry.
Aristotle, then, briefly mentions the uses of reason, and identifies four. He says, firstly, to help us in our intellectual training. Understanding how reason works will allow us to penetrate a subject more deeply. Second, in casual encounters with people we will be able to detect error or question someone on their claims more effectively. Thirdly, for use in the philosophical sciences, as we will be able to make sense of them more easily and to figure out difficulties on both sides of a problem. Lastly, in searching out and understanding the first principles of different sciences or disciplines.
If we make use of the power of reason, we will not waste any tools which would be of use to us in our relative disciplines or life.
The parts which make up reasoning are propositions (or phrased in a different way, called "problems"). Propositions are based in a subject and related to a predicate - both of which can be made up of four different parts: A genus, a species/definition, a property, or an accident.
To add to this, a definition is regards a things essence, or what it is. Aristotle is referring to the which in which we phrase the nature of a thing. A property is predicated of a subject, not in an essential way, but in a way in which it is an aspect of that thing or type of thing alone. Aristotle uses the example of grammar in relation to man. The ability to use grammar is not essential to man's essence, it is more of an effect of something deeper, yet man alone is able to do this. Therefore, it would be classified as a property. A genus is a logical and essential category which includes different types of things which share an essential quality. And finally, an accident is a relative and temporary property in that it is not essential to have that property and could be otherwise, such as the shade of color of one's skin.
Aristotle here makes the point that just as mistakes can be made in classifying something with regard to its genus, its properties, and its accidents we can also make mistakes with regard to defining a thing's species.
Here Aristotle defines "sameness" as ways of talking about the same subject but in terms of the four categories which have been mentioned here. One can speak of things as the same in terms of the genus, in terms of the same species, or in terms of something's properties or accidents. We predicate in different ways when we identify the same thing depending on the circumstance.
Aristotle points out that logic as a rational discipline is predicated on the reality of these four categories and that however you look at it, you will end up back with these categories, whether you look at each example inductively one by one or reason about the natures of things.
Aristotle then says that these four modes of predication are found in 10 categories in reality. These are: Substance, quantity, quality, relation, place, time, positions, state, activity, and passivity. Here, now, Aristotle has laid out the nature of subjects and predicates which reason and argumentation uses and requires inevitably.
Here Aristotle talks about the nature of dialectical arguments. They must begin with premises, or the inversions of premises, that are held to be the general or accepted opinion by the people or the by experts. It's not the idea that everyone already knows is obvious or the conspiracy theory, but somewhere in the middle.
Dialectical arguments also include practical moral questions about what we are supposed to do, about questions on which there is disagreement, or even questions in which there is much that is unknown and so therefore a clear answer cannot yet be had. It can also arise when the philosophers or experts contradict the common opinion of men. Aristotle presents the term "thesis" here to mean something like this is which an alternate opinion is put forth as a problem to be solved.
Induction is the passing from the individual to the general from the senses to the intellectual.
So now Aristotle has defined the subject and predicate (the material out of which arguments are built), and now he is making clear the place from which we then take arguments:
(1) the securing of propositions; (2) the power to distinguish in how many senses particular expression is used; (3) the discovery of the differences of things; (4) the investigation of likeness.