Through some years of philosophical study I've become confused about what exactly it means for me to have knowledge. What was once a familiar and seemingly clear concept has now become unfamiliar and obscure. Can it be made clear again for me? Can I ever know whether or not I know? It seems as though the more I read about knowledge the more obscured it becomes.

The topic of knowledge is an old one, going back at least to Plato who wrestled with the difference between knowledge and correct opinion. The traditional, most common understanding of knowledge is that a person knows X (whatever X stands for) if that person has a true, justified belief about X. Justification refers to evidence. This traditional understanding of knowledge has been challenged on the grounds that you might have a justified true belief about X --that Pat Jones is in Spain-- and yet the justification / evidence is spurious, e.g. imagine you are seeing Jones' identical twin, Chris Jones, in Spain and you inappropriately conclude you are actually seeing Pat. This has caused some philosophers to amend the definition to:

A person knows X if the person's belief is true and the evidence for this belief does not involve essential reasoning by way of a false premise.

Matters that remain unsettled include (a) Just how much evidence or justification is needed for one's belief to count as knowledge, and not simply a reasonable assumption? Some philosophers press for a strict, unsurpassable amount of evidence, to the effect that knowledge claims need to be infallible (not subject to error) and incorrigible (not subject to change); others adopt more flexible, less strict accounts (b) Can you know X and not be able to reconstruct the evidence that your belief(s) about X are based upon? There is a view, sometimes called reliabilism, according to which a person may know X if her beliefs are reliably true, even when the person is not consciously aware of the relevant evidence. (c) Can you know x without knowing that you know X? Many philosophers think this is possible. Children and some nonhuman animals may have knowledge without knowing that they have such knowledge. (d) Is there a significant difference between the forms of knowledge we express by the phrases "knowing how" and "knowing that"? Some philosophers contend that someone might know how to swim or ride a bike without being able to put such knowledge-claims in the form of propositions.

I believe that there is some variation in the English usage of "knowledge." I have heard people say "I knew that _______ but then I realized I was mistaken." On the traditional view, if you actually know that (say) Jones is not in Spain, it cannot be the case that Jones is in Spain.

Good luck in your philosophy! The topic of knowledge (its nature and value) is relevant to almost every domain of philosophy.

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