Overall Comments.  Fallacious arguments are nearly always invalid.  Exceptions: FA often fits the valid DD form; and CR may be valid in a very trivial way.  Fallacious arguments are ways of reasoning poorly;  hence they, by definition, cannot be strong arguments.  If you judge an argument to be invalid but strong, then do not say it's fallacious!

Formal Fallacies.  Simple arguments that fit the formsAC and DA are fallacious, invalid, and weak.  (More complex reasoning wherein AC or DA patterns are one component of a longer argument can sometimes be strong.)  Identify by doing and labelling the diagram.

Hasty Generalization, HG.  Reasoning from information about very few things (in the reasons) to a conclusion about many things.  Identify by naming the few things and the many things, and saying that those few are not enough.

False Alternatives, FA.   Two (occasionally more) alternatives are explicitly given in the reasons, but there are other alternatives that should be considered.  Identify by naming the two alternatives stated in the reasons, and then describing a plausible (not weird or far-out) missing alternative.

False Cause, FC.   Two main versions.  1)Post Hoc: Reasons explicitly say, one things occcurs before another.  Conclusion explicitly says, the earlier thing caused the later one to happen.  Identify by suggesting a some other plausible cause than the one mentioned in the conclusion.  2) Association: Reasons explicitly say, two kinds of things frequently occur together.  Conclusion explicitly says, one of them causes the other to happen.  Identify by suggesting a some other plausible cause than the one mentioned in the conclusion.

Argument from Ignorance, IG.   Absence of knowledge, or absence of proof, is explicitly stated as the reason why something is true or is known.  Identify by filling in the blanks:  failure to know (or prove, etc.)      X       is inadequate for showing (or proving, etc.)      not-X      .

Ad Hominem, AH.  The reasons criticize or find fault with a person (or group of people).  The fault-finding may be direct and vicious, or indirect and subtle.  But the conclusion is not about that person (or group of people); instead, the conclusion rejects some position or point of view that is held by that person (or group of people).  Identify by naming the person(s), stating what the criticism of them is, and describing the viewpoint that the arguer rejects without criticizing.

Equivocation, EQ.   A conclusion is reached incorrectly due to a shift in meaning of some word or phrase in the argument.  Identify by naming the word or phrase whose meaning shifts, and stating what the two different meanings are between which it shifts.

Circular Reasoning, CR.  The conclusion of an argument is, explicitly or implicitly, used as a reason for itself!  Identify by clearly explaining how it is being used as both a reason and the conclusion.  Often this can be done by noting that in the diagram, the conclusion-number appears among the reason-numbers.  Warning: a number that is inside a conditional or a disjunction is not, by itself, being used as a reason or a conclusion!