Argument from Incredulity
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[edit] Definition
Argument from Incredulity is an informal logical fallacy where a participant draws a positive conclusion from an inability to imagine or believe the converse. The most general structure of this argument runs something like the following:
- I can't imagine how P could possibly be false
- Therefore, P.
A simple variation on this is
- I cannot imagine how P could possibly be true
- Therefore, not-P.
This is a fallacy because someone else with more imagination may find a way. This fallacy is therefore a simple variation of argument from ignorance. In areas such as science and technology, where new discoveries and inventions are always being made, new findings may arise at any time.
[edit] Examples
Example 1:
- Antagonist: I can't imagine how bread rises without fairies; therefore, I believe in faeries.
Example 2:
- Antagonist: How could that dowser have made the stick move without paranormal powers? Obviously dowsing has to work.
Example 3:
- Antagonist: I can't believe the medium figured all that stuff out about me without spiritual aid; she must be in touch with the paranormal.
Example 4:
- Antagonist (Eugene Cernan, the last man to walk on the moon): "No one in their right mind can look in the stars and the eternal blackness everywhere and deny the spirituality of the experience, nor the existence of a Supreme Being. There were moments when I honestly felt that I could reach out my hand, just as the pilot John Magee says in his poem 'High Flight', and touch the face of God." (Source: Observer Magazine, 16 June 2002, cited by Julian Baggani)
In general, no inferences can be drawn from a lack of evidence. This is particularly true when the lack of evidence is merely personal incredulity and other potential explanations, are well-known to others, such as the existence of the ideomotor effect as an explanation of dowsing, or the standard cold reading stage technique as an explanation of many mediums' performances.
Argument from incredulity is also a fallacy in the hands of scientists as well; as Clarke's First Law puts it, "When a distinguished but elderly scientist states that something is possible he is almost certainly right. When he states that something is impossible, he is very probably wrong."
[edit] Exceptions to the Rule
As with argument from ignorance, in some cases we may be able to believe that our knowledge of a specific area is sufficiently complete that our imagination can be expected to cover all (reasonable) cases. In such cases, "I can't imagine that P" can be treated as a rhetorical flourish on the simple statement "not-P." For example, in this case, the following argument is reasonable (and not an argument from incredulity).
- This train station has been closed for five years, althought the line is still in use
- I can't imagine why a train would stop at a closed station
- Therefore, the train now approaching us will not stop at this station
