When discussion and debate is conducted properly it should lead to logical conclusion. However debate can often become muddied by people using what is known as 'logical fallacy'. Logical fallacy is often used to bolster ones own argument or prejudice, usually when ones own argument is very weak.
We should always watch out for the use of 'logical fallacy' as it can detract from the debate, 'muddy the waters', and lead to poor outcomes. If not spotted, its use can lead to illogical conclusions being drawn and poor decisions being made.
Attacking an opponent personally so as to undermine their argument.
Using double meaning or ambiguity in words to mislead or misrepresent the truth.
Using an isolated example rather than a sound argument or evidence.
Appeal to Authority
Using authority to claim truth.
Appeal to Emotion
An attempt to create an emotional response instead of using a valid reasoning.
Appeal to Nature
Claiming that if something is natural it is valid.
Appealing to popularity as a form of validation.
Black or White - False Dilemma - Binary Thinking
Claiming only two alternatives exist, when there are more possibilities.
Burden of Proof
Claiming that something must be disproved by others. Claiming that if it cannot be disproved then it must be true.
Composition - Division
The assumption that one thing must be applied to all.
Where two things occur, it is claimed that one is the cause of the other.
Claiming the argument must be wrong because it was poorly made or a fallacy was used when making it.
To claim that statistically independent phenomena will affect future outcomes. For example believing that if you were to flip a coin 10 times and the outcome were heads every time, that the chances of heads/tails on the 11th flip becomes something other than 50:50.
Judging something by where it comes from or who it came from rather than on its own merit.
Asking a question which implies guilt no matter how it is answered.
The claim that the middle point between two extremes must be correct.
No True Scotsman
Appealing to an example of purity to dismiss criticism or flaws. Some Scotsman put sugar on their porridge. Ah but no true Scotsman would ever put sugar on their porridge.
If something is not understood, it is claimed it is not true.
If we allow A to happen, eventually Z will happen, therefore A should not happen.
Moving the argument or making exceptions when proven to be wrong
The opponent's argument is exaggerated or misrepresented in order to undermine it.
Avoiding the argument by criticising the accuser of something else.
Finding a pattern to fit a presumption. Like shooting at a wall and then painting on a target where most of the most bullets hit.
Use of logical fallacy can be inadvertent, but it can also be used deceitfully. It is often used by people who are insistent on getting their own way.