Why do native speakers sometimes use “dispel with something” instead of using "dispel something"?

Question

Dispel is defined as a transitive verb in dictionaries. But I notice native speakers sometimes use "dispel with something" instead of using "dispel something".

I just came across this sentence said by presidential candidate Sen.Marco Rubio,

Let’s dispel with this fiction that Barack Obama doesn’t know what he’s doing. He knows exactly what he’s doing.

I've also googled and got some other examples,

Let's please dispel with the notion that opposing women in direct combat and conscription is sexist.

What myths are you trying to dispel with this book and who is the audience?

I consulted dictionaries but didn't find any examples of such usage with a preposition "with". Then why do native speakers sometimes use “dispel with something” instead of using "dispel something"? Is it grammatically correct?

Answer 1

In the first two sentences, the speaker is using the wrong word: 'dispel' when the correct word is 'dispense'. This kind of error is common enough in English that we have a word for it: Malapropism

Let’s dispense with this fiction that Barack Obama doesn’t know what he’s doing.

In the third sentence, the verb 'to dispel' applies to the myths, not the book. 'with this book' is a separate clause.

What myths are you trying to dispel?

I'm trying to dispel myths about dating.

Adding the clause back in:

What myths are you trying to dispel with this book?

I'm trying to dispel myths about dating with this book.

Answer 2

Native speakers normally don't. To many people, this sounded like an error. In cases of preposition use like this, there is no clear line between "grammatical error" and "usage error," but "dispel with something" is definitely not a usual turn of phrase. The linguist Mark Liberman made a post about it on Language Log (Badly scripted) where he discusses other possible examples of this construction. His conclusion:

Given the sparseness of this construction, I'm inclined to continue to regard it as a sporadic malaprop.