Logic

logic comes from the work “logos” in greek

logic and reasoning go hand and hand

when we reason we go through the reading, argument and inference process

reasoning is the process of providing reasons in support of an idea or action, or a statement that justifies a belief or action

we judge the validity of an argument

argument is the use of one or more reasons to support an idea or action, arguments are made of reasons (or premises) and a conclusion

conclusion key words : so, therefore, consequently

premise key words : since, because

inference is the mental process that occurs when we move from premises to a conclusion

The argument can be reasonable due to past experience, existing information or given information

forms of reasoning : deduction and induction

deduction : based on deductive reasoning, drawing a conclusion from a general statement (specific conclusion from wide statement)

induction : inductive reasoning, observing things and making generalized conclusions (starting at specific premises to form a wide statement)

a syllogism is a form of reasoning in which a conclusion is drawn from two reasons or premises

syllogisms help to see the forms of reasoning, turning an argument into a syllogism can help judge its validity

logic does not necessarily mean truth, just something that could logically make sense

antecedent : an event that exists before or logically proceeds another

consequent : an even or thing that happens as a result or effect of the antecedent

affirming the antecedent : if p then q, p, therefore q

denying the consequent : if p then q, not q, therefore not p

chain argument : if p then q, if q then r, therefore if p then r

disjunctive syllogism : either p or q, not p, therefore q

inductive reasoning is the belief that a number of observations or specific objects/events are used to develop a more general conclusion or generalization

induction can lead to new knowledge

specific observations can lead to formulation or general laws or rules with some level of probability or certainty, until exceptions are found which alters our conclusions

several examples of observation of an occurrence lead to inductive reasoning that allows general conclusions to be made

conclusions reached because of inductive reasoning are probable to a degree, conclusions are about probability and validity.

aristotle was the first person to articulate the principles and techniques of formal logic

aristotles founding work on logic is the Organon, made up of six treaties : On interpretation, prior analytics, posterior analytics, topics and on sophistical refutations, a tool he used to reflect his concepts of logic

three laws of thought : the law of non-contradiction, the law of the excluded middle and the law of identity

law of non-contradiction : something can’t be said both to be and not to be at the same time and not in the same respect

law of the excluded middle : something must either be or not be, it must be either true or false

law of identity : something is what it is

critical thinking involves judging the value of information and judging the strength of arguments

we need to judge whether information is relevant, whether it is empirical or factual, what its biases are and how reliable the source of information is

relevance : determining whether the information have any impact on the argument

empirical value : information attained through the senses and experiments

bias : a point of view

reliability : how reliable a source is