We are now in a position to outline a basic procedure for the assessment of arguments represented in standard form. We first consider arguments that have only one inference. When you represent an argument in standard form, do not include the word 'probably', or any similar word, in the conclusion - not yet. Put such words in the premises only. Once you have reconstructed the argument in this way, you should proceed as follows (and you should, looking back at the definitions given in this chapter, stop to see why the chart is arranged as it is):
1 Is the argument deductively valid?
If not, proceed to 1.
If yes, are all the premises true?
If yes, the argument is deductively sound. Stop.
If not, the argument is valid but unsound. Stop.
2 Does the argument consist of an inductive inference?
If not, proceed to 3.
If yes, write 'Probably', or suitable variant, before the conclusion of the inference. Is the inference a forceful one? If yes, proceed to 3.
If not, the argument is neither valid nor inductively forceful. Stop.
3 Is the argument inductively forceful?
If not, the argument is neither valid nor inductively forceful.
If yes, how forceful? Write 'Probably', or suitable variant, in the appropriate place in the conclusion. Are the premises true?
If yes, the argument is inductively sound. Stop.
If not, the argument is neither deductively nor inductively sound.
In the case of extended arguments, this procedure is to be carried out first with respect to the sub-arguments whose conclusions are premises of the extended argument. For example, suppose we have an extended argument whose form is like this:
Was this article helpful?