Explain what Ayer means by justification, truth, and conviction (belief), (2) the details and reasons for Gettier’s objection.

Philosophy

In the Mediations, Descartes was concerned to find knowledge that was true,
certain, and well-justified. Three centuries later, A. J. Ayer wrote that to know
something is have a justified true belief about it. Gettier objected to Ayer’s
characterization of knowledge by offering a counterexample.
In your view, are the criteria of justification, truth, and conviction necessary
and sufficient conditions for having knowledge? In other words, can we claim to
know something if we meet Ayer’s criteria? Do we need to meet all of them in
order to have knowledge? Even if we have a justified true belief, are there any
criteria missing, as Gettier seems to have thought?

Answer this question succinctly as possible. 

Explain what Ayer means by justification, truth, and conviction (belief), (2) the details and reasons for Gettier’s objection.

Offer reasons for and against your view.