Logical fallacies are errors in arguments. We need to be able to assess an argument on the logic of its presentation; that is, whether the premises lead to a valid conclusion. It is irrelevant whether or not we agree with the conclusion; we need to be able to assess whether the conclusion is based on sound premises and reasons. The more we seek to analyse others’ arguments, the better we become at constructing our own arguments.
Many people claim to be arguing rationally and logically, when all they are doing is asserting their scepticism. If there is no evidence to support this sceptical assertion, then it is still not an argument, but only an opinion.
To assess an argument, try to stand back from your personal preferences and beliefs.
We may wish to believe in the conclusion, but we can also accept that the conclusion is not logically argued.
To assess the strength of an argument, look at how the argument is constructed.
1. What is the overall conclusion(s)?
2. What are the premises/evidence/data/reasonings to support that conclusion(s)?
3. Are the premises valid?
4. Do the premises lead to a logical conclusion?
The following are examples of logical fallacies, sorted under their names. Towards the end, I have gathered the logical fallacies under their general headings (fallacies of distortion, fallacies of generalisation etc). It may help to remember them if they are categorised in this way. I have not given descriptions, or made many notes here. Read the examples, and see if you can see where the fault is in the argument. If you cannot see any fault in the argument feel free to email me.
There are several reading practices throughout - evaluate the arguments for logic and soundness and see how many fallacies you can detect. Remember, to analyse an argument means to assess whether it is valid and logical. We may actually agree with the point of the author- but we may also see that the point is not argued logically. On the other hand, we may have to admit that he argument is logical, even if we, personally, do not agree with the point. Logical and critical analysis involves us having to understand our own opinions, and put them aside.
Begging the Question (Petitio principii)
The government’s budget proposals for an improvement in our economy are fundamentally flawed; they simply will not work.
The sentence has what seems to be two parts: a premise and a conclusion: which is which??
This fallacy occurs if you assume as a premise the conclusion which you wish to reach. Often, the proposition is rephrased so that the fallacy appears to be a valid argument. For example:
"Homosexuals must not be allowed to hold government office. Hence any government official who is revealed to be a homosexual will lose his job. Therefore homosexuals will do anything to hide their secret, and will be open to blackmail. Therefore homosexuals cannot be allowed to hold government office."
Note that the argument is entirely circular; the premise is the same as the conclusion. An argument like the above has actually been cited as the reason for the British Secret Services' official ban on homosexual employees.
To cast abortion as a solely private moral question,…is to lose touch with common sense: How human beings treat one another is practically the definition of a public moral matter. Of course, there are many private aspects of human relations, but the question whether one human being should be allowed fatally to harm another is not one of them. Abortion is an inescapably public matter."
A question begging epithet is a word, often used as an adjective, which in slyly inserted to persuade the listener to accept the speaker’s judgment without having to give evidence for that judgment
Eg. That incompetent minister Bloggs should be sacked.
Compound Question /Loaded Question
A compound question is one which is phrased in such a way so as to unfairly limit the…