Dr Sohail Ansari

Validity, Truth, Soundness, Strength, and Cogency In this lesson we will finally get around to judging whether arguments are "good" or "bad". An argument can go wrong in two ways. Remember the two claims: the  claim of inference  and the  factual claim . Well, to check an argument you check these two claims. Is the  structure , or  form  of the argument such that the premises actually do support the conclusion? (In  asking this question you are checking the claim of inference) And, are the premises actually true? (Obviously, the factual claim) First we'll look at the claim of inference--at the form of the argument. If it passes that test, then we'll go on to look at the truth of the premises. Deductive Arguments A  deductive  argument is either  valid  or  invalid .  There is no in-between, no gray area. The test for validity of a deductive argument is the following:  If there is any possible way for an argument to have all true premises and a f

Deduction And Induction Arguments can be divided into two groups: deductive  arguments- involve  necessity inductive  arguments- involve  probability Remember that we are always concerned with the relation between the  premise(s)  and the  conclusion . In this lesson we are still only concerned with what an argument is  intended  to be. We are not yet concerned with evaluating arguments as good or bad. In a deductive argument it is claimed that the premises provide  necessary  support for the conclusion. In logic we are dealing with a very specific meaning of necessity, absolute necessity. For example, although it is very, very likely that the sun will rise tomorrow, it is not necessary that it do so--only very probable. On the other hand, the proposition that 2+2=4 is a necessary proposition. There is absolutely no other way around it, it follows by the meaning of those terms. Once you have internalized this sense of necessity it becomes hard to deal with "

Arguments, Premises And Conclusions   Logic  is the science that evaluates  arguments. An  argument  is a group of statements including one or more  premises  and one and only one  conclusion. A  statement  is a sentence that is either true or false, such as "The cat is on the mat." Many sentences are not statements, such as "Close the door, please" , "How old are you?" A  premise  is a  statement  in an  argument  that provides reason or support for the conclusion. There can be  one  or  many  premises in a single argument. A  premise  is a previous statement or proposition from which another is inferred or follows as a conclusion. ‘If the premise is true, then the conclusion must be true’ A conclusion  is a  statement  in an  argument  that indicates of what the arguer is trying to convince the reader/listener. What is the argument trying to prove? There can be  only one  conclusion in a single argument.   In this lesson you wi