What is a logical fallacy?

Logic is the study of reasoning — the nature of good and proper reasoning and of bad and improper reasoning. A logical fallacy, then, is an invalid form of argument — incorrect or faulty reasoning.

What is equivocation? This is a logical fallacy that stems from the ambiguous meaning of certain terms/words. An illustration may help:

• Only man is logical.
• No woman is a man.
• Therefore, no woman is logical.

The word "man" in the first statement above literally means all mankind. In the second statement, man means only a man, but not a woman; for instance, Adam, but not Eve. Therefore, because of the subtle shift in meaning of terms/words, this makes the conclusion in the third statement improper, incorrect, and literally false.

There are numerous types of logical fallacies. Here are a few: (1) affirming the consequent; (2) anthrocentric fallacy; (3) appeal to authority; (4) a priori fallacies; (5) arguing from "is" to "ought"; (6) argumentum ad baculinum; (7) argumentum ad captandum; (8) argumentum ad crumenam; (9) argumentum ad hominem; (10) argumentum ad ignorantiam; (11) argumentum ad lazarum; (12) argumentum ad misericordiam; (13) argumentum ad populum; (14) argumentum ad verecundiam; (15) argumentum ex silentio; (16) begging the question; (17) circular reasoning; (18) equivocation; (19) fallacy of false alternatives; (20) fallacies of interrogation; (21) flamboyance; (22) gadarene swine fallacy; (23) genetic fallacy; (24) hasty generalization; (25) if-then fallacies; (26) ignoratio elenchi; (27) invincible ignorance; (28) naturalistic fallacy; (29) non sequitur; (30) paralogism; (31) performative contradiction; (32) petitio principii; (33) poisoning the wells; (34) post hoc ergo propter hoc; (35) red herring; (36) straw man fallacy; (37) tu quoque fallacy; and (38) undistributed middle, etc.

I'll leave it up to the reader to investigate various definitions of the words and phrases above.