My favorite example of equivocation comes from my graduate logic professor, Dr. Johnstone (Penn State):
Hot dogs are better than nothing
Nothing is better than steak.
Therefore, hot dogs are better than steak.
The oddity of the conclusion should tell us that something has gone seriously awry with the argument - even though both premises are, on first blush, true.
What has gone wrong - "nothing" is used in two different senses in the premises. In the first premise, "nothing" means something like "nothing to eat at all," while in the second premise "nothing" means something like "no possible food choice on the planet." It is the slippage from the one sense to the second that allows for the peculiar conclusion - but this slippage rests on equivocation in the meaning of "nothing."
A more serious example is suggested by Mary Anne Warren, in her analysis of a familiar anti-abortion argument:
1) It is wrong to kill innocent human beings
2) Fetuses are innocent human beings
Therefore, it is wrong to kill fetuses.
Warren argues that, in fact, this argument faces its own dilemma: either it is guilty of equivocation - or it is guilty of question-begging.
It is easy enough to argue that "innocent human beings" means two different things in the premises - and thus the argument equivocates. For example:
innocent human being in premise 1 = "conscious of moral choice, but not guilty of committing/choosing an immoral act"
innocent human being in premise 2 = "innocent because the fetus is not capable of moral intentions and choices in the first place"
IF two different senses of "innocent human being" are thus at work in the argument - then the argument equivocates: while we might agree that it is wrong to kill innocent human beings in the first sense - this is not immediately relevant to fetuses as innocent human beings in the second sense, and so the conclusion does not follow.
[Alternatively, if we are not equivocating - if we somehow mean "innocent human beings" in the exact same sense in both premises - then the argument begs the question. That is, the premises taken together would then mean:
it is wrong to kill innocent human beings, where "innocent human beings" includes fetuses.
BUT: this is precisely the conclusion we're seeking to establish (or, the question under discussion). Our argument in this version then amounts to
[P] it is wrong to kill innocent human beings, where "innocent human beings" includes fetuses
[C] therefore it is wrong to kill fetuses [as innocent human beings]
The argument thus goes in a circle, as the premises already include everything we're attempting to assert in the conclusion - alternatively, the premises offer no additional argument, evidence, or information in support of the conclusion. Rather, the premises merely restate the conclusion, and the conclusion merely restates the premises. Or: the question, "Is it wrong to kill fetuses?" is begged as the answer to the question is merely assumed in the premises.
A still more serious example of equivocation comes in the debate among religious communities over abortion. See Judaism vs. Christianity: Hebrew vs. Greek texts as the source of divergent teachings on abortion
Other possible examples of equivocation:
1. Ross Perot: Now there's a choice for President!
2. Our military operation in Panama was not, I repeat not, an invasion. That would violate the national sovereignty of one of our strongest friends and allies. "Operation Just Cause" was simply the result of my directing our armed forces to protect the lives of American citizens in Panama, to execute pre-planned missions in Panama, to conduct efforts to support the democratic processes in Panama, and to assure the integrity of the Panama Canal while creating an environment safe for American citizens. (based on quotes from a recent American President.)
3. Of course I don't have a problem with alcohol. I'm getting my school work done, showing up for my job on time, and doing o.k. with my boyfriend. O.k., so I have a drink or two every night -- but I just do it to relax and be social. Besides, a family friend with a heart condition was told by his doctor to have a glass of wine every day to help him relax and improve his digestion, so my drinking is just my way of staying healthy.
[Hints: the speaker here is a 19 year old female; the family friend with the heart condition is a male in his late 40's recovering from a heart attack.]
4. 1) Thank you for your manuscript. 2) I shall lose no time in reading it.
5. [The Second Amendment to the Constitution states: "A well- regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed." A number of law professors hold that "the right to bear arms" is a _right restricted to members of a militia organized by the state_. For the sake of the following, assume that this meaning is what is intended in the Second Amendment.]
The Second Amendment guarantees the right to bear arms. So if I, as a private citizen, have the right to bear arms - I therefore have the right to purchase a handgun for any purpose I choose.
6. My father started a DARE program about 45 years ago when he told me "If you dare mess with drugs, cigarettes or alcohol, I'll wear out my razor strap on you."
7. "We can never have jam today," the Queen insisted.
"But it must come to jam some day," Alice protested. "After all, the rule is, 'jam every other day.'"
"Precisely," said the Queen. "'Jam every other day.' But today is not any other day, you know."
8. Einstein demonstrated that our experience of time/space, while absolute within a given frame of reference (i.e., the speed of light within the frame of reference is always measured as 300,000 km/sec), is also relative to that frame of reference. (We would observe space/time in a different frame of reference - i.e., one moving close to the speed of light relative our own - to be distorted compared to our own, e.g., time "there" would slow down compared to "here," etc.)
So I guess all things are relative.
9. You're born from nothing. You go back to nothing. What do you lose? Nothing! So always look on the bright side of life... (Monty Python)