The sixth question is another that has a predictable format. It asks candidates to assess the credibility of two witnesses, making two points of credibility about each. Each point is worth up to 4 marks, so that’s 16 in total; this is another big question that can make or break your overall grade.

Question Format

The question should look something like this: “Consider witnesses A and B. Assess the credibility of evidence relating to them. For each, make two points of assessment, each of which should: identify a claim made; assess how this is strengthened or weakened by any relevant credibility criterion; state what you must suppose to be true in order to reach your assessment.”

Strategy

The first thing that you need to do for each point of credibility is identify a relevant claim that the witness makes. Doing this is worth 1 mark for each point of credibility. This part of the question is very simple; nearly everyone gets these marks.

The second thing that you need to do is to apply a relevant criterion of credibility. For a proper application, you should make explicit whether the credibility of the claim is strengthened or weakened by this criterion, and explain your judgement.

If you think that the witness’s credibility is strengthened by his relevant expertise, state what his relevant expertise is and why you think he has it (e.g. “Joseph’s claim that Catholics don’t worship Mary is strengthed by his relevant expertise in Catholicism, what with him being Pope”).

If you think that their credibility is weakened by vested interest, say what the vested interest is (e.g. “Gary’s claim that the other driver caused the accident is weakened by his vested interest to avoid being blamed himself and having to claim on his insurance”).

If you think that they lack neutrality, say who they’re biased towards or against and why (e.g. “Bart’s claim that Sideshow Bob is plotting to kill Selma is weakened by bias against Bob as Bob has tried to kill him several times in the past”).

For each point of credibility, there is 1 mark available for proper application of a criterion of credibility.

The third and final part of this question is where most students fall down. It asks you to identify what assumptions you must make in order for your point of credibility to hold.

For each point of credibility, there are 2 marks available for doing this (you only need to identify one assumption to get them both).

So, for example, the point about Joseph holds “… assuming that being Pope involves knowing about theology rather than just performing Mass.”

The point about Gary holds “… assuming that the accident caused enough damage that it’s worth getting an insurance company involved.”

The point about Bart holds “… assuming that he and Bob haven’t been reconciled.”