Cognitive Psychology Reasoning Reasoning • Judgment and decision making involve evaluating opportunities and selecting one choice over another. A related kind of thinking is reasoning. • Reasoning is the process of drawing conclusions from principles and from evidence. In reasoning, we move from what is already known to infer a new conclusion or to evaluate a proposed conclusion. • At a very basic level reasoning can be split into two distinct categories: deductive and inductive reasoning. Deductive Reasoning • Deductive reasoning at its most basic level is simply reasoning from the general to the particular, for example, starting with a theory and looking for instances that confirm the deduction. • Deductive reasoning is based on logical propositions. • A proposition is basically an assertion/statement, which may be either true or false. • Examples are “Cognitive psychology students are brilliant,” “Cognitive psychology students wear shoes,” or “Cognitive psychology students like peanut butter.” • In a logical argument, premises are propositions about which arguments are made. • Cognitive psychologists are interested particularly in propositions that may be connected in ways that require people to draw reasoned conclusions. That is, deductive reasoning is useful because it helps people connect various propositions to draw conclusions. Syllogistic Reasoning • One branch of deductive reasoning is that of syllogistic reasoning. A syllogism or logical appeal is a kind of logical argument in which one proposition (the conclusion) is inferred from two others (the premises) of a certain form. • Circle diagrams may be used to represent categorical syllogisms such as the one shown here: • All cognitive psychologists are pianists. • All pianists are athletes. • Therefore, all cognitive psychologists are athletes. Inductive Reasoning • Inductive reasoning involves moving from specific facts to a conclusion. It involves going from a series of observations of a specific event to a rule encompassing all such events. • For example, if I find that multiplying 3 by 2 gives me an even number and 5 by 2, likewise 4 by 2, then I may put forward a hypothesis that says that if I have a number (n) and I multiply it by 2 the resulting number will always be an even one. • Or • Seawater is salty, in fact throughout my life every seawater sample I’ve experienced has been salty therefore, I can hypothesise that all seawater is salty. • In evaluating an inductive argument, we must decide how strong the argument is because in inductive reasoning, we may never reach a logically certain conclusion • A strong argument is defined as having an outcome that is likely to be true and a weak argument as having an outcome that is unlikely to be true. • There are a number of factors that can have in impact on the strength of an argument: • How well does my observation fit all other observations, or is my observation a good example of category? E.g., if I see a person patting a lion in a zoo, I might induce that all lions are safe, but my observation was not a very good example of the group of ‘lions’. • How many observations have I made? If I’ve observed that every time I touch ice it is cold then this would start to create a strong argument for ice always being cold. • Are my observations backed up any other scientific descriptions of the phenomenon or category that I’m observing? If I observe that every fish I have ever seen can survive underwater, and the biological evidence suggests that fish have gills that can absorb oxygen from water, then this may strengthen the argument for fish being able to breathe underwater • Inductive reasoning is much more similar to the problems we encounter in real life. It models the way that the majority of us attempt to make rational judgements about the world we live in.
