Essay On Natural Deduction

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RULES OF INFERENCE IN NATURAL DEDUCTION Natural deduction is a technique that is used to try to prove that some reasoning is correct or to check the validity of a certain sequent. This technique has two positions; a set of rules put in place to construct proofs of tautologies in an orderly manner and the application method of these rules. Natural deduction mostly has or uses two kinds of rules which are the rules of replacement and the rules of inference. In the rules of inference as our main point, (moura, 2010) defines it as a template for building a valid argument. A set of rules can be put in place to infer any of the conclusion that are valid if they are complete and not inferring to a conclusion that is invalid. There a lot of rules of inference in natural deduction which are there to check the…show more content…
Chain argument or hypothetical syllogism is another inference rule which a syllogism is having a valid argument form where it has a conditional statement for one or both of its premises where there is a chain of arguments and this can formally be stated as (P→Q,Q→R)/(∴P→R) where this rule is that when P→Q and Q→ R are seen on the line of proof, then P→R can be placed on a subsequent line. For example, If I do study hard, then I will pass the exams. If I do pass the exams, then I will be rich Therefore, if I do study hard, then I will be rich. Disjunctive syllogism also is another rule of inference where it has a disjunctive statement in one of its premises and that the argument is valid in form. Disjunctive syllogism can be stated formally as P or Q, not P therefore Q or P˅Q, ¬P ˫Q. for example. Levi is either going to watch football or netball. Levi is not going to watch netball Therefore, Levi is going to watch football. The other rule of inference is constructive dilemma. This is an inference that if P implies Q and R implies S and either P or R is true, then we conclude that Q or S has to be true or stated as(P→Q,R→S,P V R)/(∴Q V
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