# Logic

## Arguments[edit]

### Formal logic is the only logic[edit]

Some apologists argue that formal logic is the only form of logic worth considering:

*"The point is that there’s only one type of logic that helps us discover truth. It’s the one built into the nature of reality that we can’t avoid using. Despite this, people will try to tell you that logic doesn’t apply to reality, or logic doesn’t apply to God, or there are different types of logic, and so on. But as they say such things, they use the very logic they are denying.*^{[1]}"

*"The Laws of Logic are absolutely true. [...] People's minds are different. What one person considers to be absolute may not be what another considers to be absolute. People often contradict each other. Therefore, The Laws of Logic cannot be the product of human, contradictory minds.*^{[2]}"

*"The street is either filled with cars or it is not. It is either safe to cross or it is not. BOTH realities cannot exist at the same time. One truth must exist at the exclusion of the other.*^{[3]}"

Not everyone agrees that logic is objective or absolute. There are various alternative systems of logic, collectively called non-classical logic. People temporarily *assume* that logic is absolute for the sake of their argument. That assumption does not make it absolute in reality. The particular choice of logic system they adopt is a subjective choice. The way experiences are interpreted into objects in order that logical may be applied is subjective.

Someone claiming that an object cannot be A and not-A at the same time, which is indeed a law of logic, shows they have a lack of understanding of quantum mechanics. It is quite common for things to be an different mutually-exclusive states simultaneously, such as Schrödinger's cat, or even in two different places at once, as in the double-slit experiment. Attributes such as alive/dead, inside/outside are often not mutually exclusive. This shows that logic does not always reflect reality and is therefore not absolute. In other words, can be be absolutely sure the law of non-contradiction is applicable in a particular physical situation which may be subject to quantum effects?