12/3/13 Critical thinking web

philosophy.hku.hk/think/fallacy/ir.php 1/1

2004-2013 Joe Lau & Jonathan Chan Copyright and terms of use

[TUTORIAL F03] Irrelevance

Fallacies of relevance are of two kinds:

F03.1 Taking irrelevant considerations into account

This includes defending a conclusion by appealing to irrelevant reasons, e.g. inappropriateappeal to pity, popular opinion, tradition, authority, etc. An example would be when a studentfailed a course and asked the teacher to give him a pass instead, because "his parents willbe upset". Since grades should be given on the basis of performance, the reason beinggiven is quite irrelevant.

Similarly, suppose somone criticizes the Democratic Party's call for direct elections in HongKong as follows : "These arguments supporting direct elections have no merit because theyare advanced by Democrats who naturally stand to gain from it." This is again fallaciousbecause whether the person advancing the argument has something to gain from directelections is a completely different issue from whether there ought to be direct elections.

F03.2 Failing to take relevant considerations into account

For example, it is not unusual for us to ignore or downplay criticisms because we do not likethem, even when those criticisms are justified. Or sometimes we might be tempted intomaking snappy decisions thinking that our decisions are the best when in fact we should beinvestigating the situation more carefully and doing more research.

Of course, if we fail to consider a relevant fact simply because we are ignorant of it, then thislack of knowledge does not constitute a fallacy.