Emma asked:

What is the role of justification in distinguishing between knowledge and true belief?

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Offhand, I'd say that just because a belief is true doesn't necessarily imply that you know why, i.e.,
that you know it's justification, i.e., that you knowthat it's true. So knowledge, as justified belief, can
imply that you also know the justification, depending, of course, on how you understand "justification".
On the other hand, can something justify your belief, so that it becomes knowledge, yet you don't
know of that justification? Well, why not? Then you'd have knowledge but not know you have it. But in
that latter case, you could not distinguish between knowledge and true belief.

Steven Ravett Brown

Perhaps I might expand on this answer a little?

Justification is typically understood to be constitutiveof the difference between knowledge and true
belief. For a pithy explanation why, see Kenneth Stern's answer to a related question at: Answer page
15, Question 19

The account of knowledge as justified true belief is sometimes called the 'tripartite definition' —
justification, truth and belief being the three parts. It originates with Plato (see Theaetetus201 and
Meno98) and it is very widely accepted as at least giving necessary conditions for knowledge.
(Although some social scientists refer to any justified belief as knowledge, irrespective of whether it is
true, this is a deplorable habit which leads to unnecessary confusion and hostility when they address
wider audiences).

The tripartite definition has been the focus of much intense scrutiny since Edmund Gettier published
apparent counterexamples to its sufficiency in a hugely influential and charmingly brief paper 'Is
justified true belief knowledge?' Analysis23(1963), reprinted in A. Phillips Griffiths Knowledge and
belief(Oxford, 1967) and many other places. Gettier cases involve beliefs which are true and
apparently justified, but which do not seem to be knowledge.

One of Gettier's own examples should make this clearer: Smith and Jones are to be interviewed for
the same job. Smith observes Jones, who he has good reason to suppose is much the better
qualified candidate, nervously counting his pocket change. Hence he forms the justified belief that the
man who will get the job has ten coins in his pocket. However, unbeknownst to Smith, he too has ten
coins in his pocket, and unexpectedly, he gets the job. So Smith's belief is true and justified--but it
doesn't seem like knowledge.

Here the truth of the belief and the justification for believing it are not linked in 'the right way'.
Needless to say, it is a far from simple business to specify what the right way is in sufficiently
watertight terms.

Andrew Aberdein