Search results
Results from the WOW.Com Content Network
This problem lies beyond the deductive reasoning itself, which only ensures that the conclusion is true if the premises are true, but not that the premises themselves are true. For example, Spinoza's philosophical system has been criticized this way based on objections raised against the causal axiom, i.e. that "the knowledge of an effect ...
An argument that is not valid is said to be "invalid". An example of a valid (and sound) argument is given by the following well-known syllogism: All men are mortal. (True) Socrates is a man. (True) Therefore, Socrates is mortal. (True) What makes this a valid argument is not that it has true premises and a true conclusion.
But the fact that new information is added means that this additional information may be false. This is why non-deductive reasoning is not as secure as deductive reasoning. [58] [64] A closely related aspect is that non-deductive reasoning is defeasible or non-monotonic. This means that one may have to withdraw a conclusion upon learning new ...
Such reasoning itself, or the chain of intermediates representing it, has also been called an argument, more fully a deductive argument. In many cases, an argument can be known to be valid by means of a deduction of its conclusion from its premises but non-deductive methods such as Venn diagrams and other graphic procedures have been proposed.
A form of deductive reasoning that concludes one disjunct must be false if the other is true and a disjunction is given (if and not , then ). disquotationalism A theory of truth that focuses on the disquotation principle, which suggests that the function of the truth predicate is to remove quotation marks to form equivalent sentences.
Non-deductive logic is reasoning using arguments in which the premises support the conclusion but do not entail it. Forms of non-deductive logic include the statistical syllogism , which argues from generalizations true for the most part, and induction , a form of reasoning that makes generalizations based on individual instances.
The argument itself could have true premises, but still have a false conclusion. [3] Thus, a formal fallacy is a fallacy in which deduction goes wrong, and is no longer a logical process. This may not affect the truth of the conclusion, since validity and truth are separate in formal logic.
For example, the proposition that water is H 2 O (if it is true): According to Kripke, this statement is both necessarily true, because water and H 2 O are the same thing, they are identical in every possible world, and truths of identity are logically necessary; and a posteriori, because it is known only through empirical investigation.