TYPES OF REASONING
Two main processes allow conclusions to be drawn from sets of premises: inductive and deductive reasoning. Hierarchies of modular arguments can link simpler and more complex arguments.
Reasoning involves the process of inference.
DEFINITION: Inference is judging conclusions to be true based on one or more premises (Barker, 1989).
However, how do we know if we correctly come to conclusions based on the available premises?
The field of Logic studies how to make valid inferences.
Throughout history, concepts of logic have evolved and changed (Thompson, 1992). However, one common categorization splits logic into two main fields. First, "Formal" logic studies the structures ("forms") of valid and invalid arguments. Formal logic can be abstract, and use mathematical symbols and specific operations. Second, "Informal" logic, or "the grammar of argumentation," studies the practical aspects of using language to persuade others (Thompson, 1992). Scientific communication is primarily based on logic and not persuasion.
How do scientists use logic to make inferences? Scientists use two primary modes of inference to support conclusions, DEDUCTIVE and INDUCTIVE reasoning (Moore and Parker, 2017). HIERARCHICAL structures can connect the conclusions of modular inductive or deductive arguments to build larger arguments.
SUMMARY
Two main types of reasoning are used for reasoned arguments: deductive and inductive reasoning.
Deductive reasoning allows us to come to conclusions (e.g. make predictions) based on information that we already know. “Knowing” something means either that the information is well-supported by evidence, or that we assume that the information is true. Deductive arguments are “valid” if they have a strong structure: if the premises are true, then the conclusions are also true. Deductive arguments are “sound” if they have a strong structure AND have true premises. However, it is important to avoid using (or being fooled by) logical fallacies that can appear reasonable, but are actually misleading.
Inductive reasoning allows us to generate knowledge and understanding based on observations. In fact, inductive reasoning is the only way that we can gain general knowledge about the world. However, inductive reasoning can never lead to proof: we cannot be 100% certain of conclusions based on inductive reasoning. For example, inductive reasoning is generally necessary to support or reject “general” hypotheses, or scientific models of the world. Therefore, empirical science cannot “prove” hypotheses, only become more and more confident that the hypotheses are consistent with observations. Moreover, we must be sure to avoid inductive “fallacies” when using inductive reasoning to support conclusions.
Using graphical frameworks and hierarchies such as trees, outlines, and literatures can help to plan, organize, and present reasoned arguments.
We can finalize our CERc framework by adding inductive reasoning:
