The CONTEXT statement
Contexts exist in Ampersand for the purpose of dealing with truth. Within one context there can be no contradictions. The Ampersand way of dealing with a contradiction is either to resolve it or to separate them in different contexts.
A context is a set of Statement in the language of this context, which are true within the context.
The world is full of contradictions. Examples:
- Bob's personal income over March 2013 according to Bob's employer differs from Bob's personal income over March 2013 according to the National Tax Authority.
- The police can be convinced that Peter X commited the crime, yet his attorney is convinced he is innocent.
- One computer system can tell that the person with social security number 721-07-4426 was born on April 27th, 1943, while at the same time another computer system tells me this person was born on May 3rd, 1952.
In language philosopy, the idea of a context was invented to give truth a place.
- In the context of the National Tax Authority, Bob's personal income over March 2013 can be computed to precisely one amount. In the context of his employment, Bob's personal income over March 2013 can be different, because that is another context.
- The job of a court of law is to create a new truth, whose consequences (e.g. imprisonement) can be enforced by law. The court creates a new context, in which conflicts between the (different) truths of both parties are resolved by a decision of the court.
- If two computers operate in the same context, yet disagree on matters of fact, we say there is an error. It is likely that in this example someone must step in to determine which date of birth is correct (if any). The error could be detected because we know (i.e. we have a rule that says) that a person must have a unique date of birth.
Ampersand uses contexts to organize truth. Within one context, there is a single truth and there are no contradictions. For this reason, a context defines a language by means of concepts and relations, in which utterances can be made. We say that these utterances make sense in that context.