Knowledge means the things which are true, as opposed to opinion. Information which is correct is knowledge. Knowledge can always be supported by evidence. If a statement is not supported by evidence, then it is not knowledge. The evidence makes it justified; it is not an opinion or a guess.
Knowledge can refer to a theoretical or practical understanding of a subject. This was the point of Ryle's distinction between "knowing that" and "knowing how". It can be implicit (as with practical skill or expertise) or explicit (as with the theoretical understanding of a subject); it can be more or less formal or systematic. In philosophy, the study of knowledge is called epistemology. The philosopher Plato defined knowledge as "justified true belief". This definition is the subject of the Gettier problems.
All knowledge is a claim to be true, but the claim can be incorrect. The only claims (propositions) which are certainly true are circular, based on how we use words or terms. We can correctly claim that there are 360 degrees in a circle, since that is part of how circles are defined. The point of Aristotle's syllogism was to show that this kind of reasoning had a machine-like form:
- If all swans are white, and this is a swan, then it must be white.
But actually, in the real world, not all swans are white.
The most widely accepted way to find reliable knowledge is the scientific method. Yet one thing all philosophers of science agree is that there is that scientific knowledge is just the best we can do at any one time. All scientific knowledge is provisional, not a claim of absolute truth.
Religion and knowledge
Knowledge in religion is different in that it depends on faith, belief and the authority of religious leaders, not on evidence of a scientific or legal kind. There are differing views on whether religious statements should be regarded as knowledge.
In many expressions of Christianity, such as Catholicism and Anglicanism, knowledge is one of the seven gifts of the Holy Spirit. In the Garden of Eden knowledge is the factor that made humans greedy and treacherous. But in the Book of Proverbs it states: 'to be wise you must first obey the LORD' (9:10).
In Islam, knowledge has great significance. "The All-Knowing" (al-ʿAlīm) is one of the Names of God, reflecting distinct properties of God in Islam. The Qur'an asserts that knowledge comes from God (2:239) and various hadith encourage getting knowledge. Muhammad is reported to have said "Seek knowledge from the cradle to the grave" and "Verily the men of knowledge are the inheritors of the prophets". Islamic scholars, theologians and jurists are often given the title alim, meaning 'knowledgeable'.
- Ryle, Gilbert 1949. The concept of mind. London: Hutchinson, Chapter 2 Knowing how and knowing that.
- "knowledge: definition of knowledge in Oxford dictionary (American English) (US)". oxforddictionaries.com.
- "Part Three, No. 1831". Catechism of the Catholic Church. Retrieved 2007-04-20.