Logical Opposition

[Julie777]

Hello!

While I was solving parellel reasoning, I just got confused about verbs and its logical opposition.

So basically, 'CAN' is logical opposition of 'CANNOT', but 'WILL's logical opposition is 'MAY NOT', not 'will not,' right?

But does also 'CAN' be logical opposition of 'MUST'?

Here's what I thoguht. If you are certain about something(must), the logical opposition of it is that you are not certain(can). That's how I end up here. Can you explain 'logical opposition' more specifically?

Thanks in advance!
Julie

[Jeff Wren]

Hi Julie,

Logical opposites take whatever subject under consideration and divide it into two parts.

For example, the logical opposite of the word "cold" is "not cold," which literally includes every temperature that doesn't reach the threshold of "cold." The word "hot," on the other hand, would be considered the polar opposite of "cold" rather than the logical opposite because it's at the other end of the temperature spectrum.

For words like "can, cannot, will," etc., it can be helpful to think of these using percentages.

For example, if something "cannot" happen, then it has a 0% has of happening.

The logical opposite of "cannot," which would be "can," means it has a 1-100% chance of happening (literally every possibility except 0%). The important thing to note here is that "can" includes 100%. In other words, if something "must" or "will" happen (meaning a 100% of it happening), it is also true that it "can" happen. If something "will" happen, it would have to be able to (i.e. can) happen.

So "can" is not the logical opposite of "must." "Must" actually falls within the scope of "can."

The logical opposite of "must happen" is "not necessarily happen" (meaning a 0-99% chance of happening (literally every possibility except 100%). "May not happen" is just another way of saying that it will "not necessarily happen."

"Will not happen" on the other hand, is the polar opposite of "will happen."

For example, if a question on the LSAT asks for an answer that "Must Be True," the 4 incorrect answers will be the logical opposite, which is "Not Necessarily True."

While it may seem like "not necessarily happen" and "can happen" are the same, they are not. They largely overlap but differ at the endpoints.

More information about logical opposition can be found in lesson 2 of The PowerScore LSAT Course.