Safalra's Website Philosophy Logical Fallacies Perfect Solution

Perfect Solution

Perfect Solution refers to the fallacy of using an argument of the form:

  1. Proposed solution S does not fully solve problem P
  2. Therefore S should not be implemented

An argument of this form is most convincing when the existence of a perfect solution seems possible.

Relation to Denying The Antecedent

Perfect Solution is a special case of the fallacy of Denying The Antecedent if we accept the additional premise that a perfect solution should be implemented. With this additional premise, the above argument can be rewritten:

  1. If proposed solution S fully solves problem P then S should be implemented
  2. Proposed solution S does not fully solve problem P
  3. Therefore S should not be implemented


This fallacy is often employed by those who believe no action should be taken on a particular issue, and use the fallacy to argue against any proposed action. For example the following argument is often employed by those who believe governments should not intervene in public health matters (note, however, that it is far from their strongest argument):

  1. Few people change their behaviour in response to public health advertisements
  2. Therefore public health advertisements do not solve public health issues
  3. Therefore the government should not produce public health advertisements

The counter-argument is that the slight improvement in public health is worth the expense of producing the advertisements. Those opposed to this form of government intervention should argue against it directly rather than employ the Perfect Solution fallacy (and indeed their strongest arguments do not rely on the fallacy).

A note on cost-benefit analysis the extent of a problem

When deciding whether a proposed solution to a problem should implemented, the deciding factor should be whether the benefits from implementing the proposed solution outweigh the costs (and not whether the proposed solution fully solves the problem). Costs and benefits can be difficult to quantify, however, and may take the form of complex social effects or abstract notions of utility.

In reality, all problems are constructed from smaller problems and are part of larger problems. Any solution that does not solve all problems could be regarded as imperfect, and so the Perfect Solution fallacy could be employed to justify complete inaction. Instead, a proposed solution can be regarded as completely solving a smaller problem (specifically the subset of the problem it was intended to solve).

Further reading

For a comprehensive reference on logical fallacies and the principles of good argument, see Attacking Faulty Reasoning: A Practical Guide To Fallacy-Free Arguments: