Gettier cases

Previously, we have discussed what is knowledge and offered the traditional tripartite definition of propositional knowledge as Justified True Belief:

i). There is a belief, eg. Humans are mammals;

ii). The belief must be true, eg. Humans are indeed mammals;

iii). The belief is justified, eg. Humans have the physiological characteristics of mammals.

The American philosopher Edmund Gettier argued in a famous paper in 1963 that we can have a JTB and yet still not have knowledge, although there were precedents to his analysis. Gettier cases provide counterexamples which raise concerns about the nature of justification. Bertrand Russell provides the example that you could look at a mechanical clock which says 2 o’clock and form the belief that it is 2 o’clock. Your belief is true because it really is 2 o’clock at that moment. However, the clock is not working for it stopped twelve hours ago, but even a non-working clock is correct twice a day. Thus, you were justified in believing that it was 2 o’clock, for your justification was based on the reasonable assumption that the clock was working. You thus fulfilled the requirements of JTB. Yet you were lucky that it was 2 o’clock.

It would seem sensible to add a fourth condition to the definition of knowledge. One suggestion is to revise the JTB as follows:

i). There is a belief;

ii). The belief is true;

iii) The belief is justified;

iv) ‘Justified’ means that the belief is not based on luck or falsehoods.

Thus, JTB is a necessary but not a sufficient condition for knowledge.

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