Is logic always consistent? If so, is it merely so by definition, or is it a law?

Question

...'by definition' means defining logic as that which is consistent.
...as a 'law' means logic has been consistent all along, but one doesn't know why.

yvanoseki,
i understand wat u say, but i'm questioning the basis... why can't it be A and notA? One may say its obvious. But ultimately is it obvious because that has what one has observed to be consistent all along?

Answer 1

logic proceeds to a conclusion stepwise. Each step following in fact from the preceding. Thus, by nature, it is consistent. A natural law is one where no exception has been found.

Answer 2

The very basis of logic is that you can not accept a fact and its opposite. (A or not A), but never (A and not A). If you posit a fact (Or premise), then you're automatically denying its opposite.
Therefore, logic is, by definition, guaranteed to be consistent, as long as it is considered only as an internal system. You can posit a number of premises, so long as these premises are not inconsistent (do not lead to contradictions).
But this is a closed system. As soon as you start making assertions about the outside world, you will find out things aren't always as they seem or as you first thought. When such inconsistencies appear, science has to step back and look at what went wrong. Either a) You made a mistake in your observations b) Your logic is flawed (but not logic itself) or c) There is another fact you neglected to factor in.
But as a closed system, logic must be consistent. Otherwise, it would not be logic.

Answer 3

Leibniz argues that there is a principle (I guess you could call it a law) called the principle of non-contradiction. This is the notion that A and not-A is always false. But there are other logical systems that incorporate paradoxical ontologies, such that A and not-A can both be simultaneously true, such as acintya-bhedabheda-tattva (existence as simultaneous unity and difference). So, it really depends upon whose logic you use.

According to Hegel's logic, knowledge consists in the 'resolution' of contradictions, so that even contradictions are not necessarily pernament contradictions, but problems to be solved.

Answer 4

.Logic as its own subject is as logic as its own object? No. Self as subject as its own logic is not as logic as its own object. Self and logic do not exist isolated as individuals nor particulars. Logic as means to ends is not the creator for ends. If there were only one universal end, then logic could not possibly produce anything other than self consistency.

Answer 5

I say by definition, but sometimes logic is personal view.

Answer 6

no