1. Appeal to nature
    A rhetorical tactic in which it is proposed that "a thing is good because it is 'natural', or bad because it is 'unnatural'.


    1. It is morally permissible to eat pigs because it is natural. Humans have the teeth for it and it is the cycle of life.

    2. Homosexuality is immoral because it is unnatural

    Someone may be naturally violent but it doesn't mean it is good to act on those violent impulses.

    Poisonous berries may be natural but it does not mean that they are good in a health sense. Chemotherapy may not be natural but that does not mean that it is bad.

    There is also vagueness in the term 'natural'. What is natural to one person can be unnatural to another.

    It is logically inconsistent to believe that some natural acts are moral and some are immoral
  2. False dichotomy (black and white thinking fallacy)
    When we illegitimately limit the options available


    You are not a Democrat therefore you must be a Republican

    If you don't vote for this law, you are a Nazi

    Sometimes they really are limited options. For example God either exists or He doesn't exist

    In psychology, it is called polarized thinking

    Do not rely on emotion alone, because it often sees in black and white
  3. Ad hominem fallacy
    When we try to disprove a conclusion by criticizing the person or the person circumstances instead of their argument.


    Some Catholic priests are pedophiles so their beliefs about God must surely be false

    Your argument against eating meat is bad because I saw you eating meat

    Clinton's law is bad because he's a jerk and he cheated on his wife


    Ad hominem fallacies illegitimately focus on the person rather than their argument
  4. Genetic fallacy
    Whenever we dismiss a claim because of its origin or history


    You can't believe Bob's idea because it came from his dream

    That's not possible because he got the idea from a science-fiction film

    Pythagoras Theorem can't be true because he got it after smoking a joint


    • To avoid this fallacy focus on the argument itself not on its origin or history
    • A bad source doesn't make an argument bad. Bad premises make an argument bad

    People fall for this fallacy because they can confuse reason with causes
  5. Slippery slope fallacy
    This is when we argue that A will cause B and B will lead to undesirable C. Since we don't want C, we shouldn't do A.


    Humans will eventually be marrying trees and raccoons if we allow gay marriage

    If I loan you a dollar today you're going to ask me for $20 tomorrow and $100 the next day so I shouldn't loan you a dollar


    There is no good justification why the first step will lead to the others

    The above examples are good arguments if there is good evidence that A will lead to be and B will lead to C, but not in its own
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