4. Modus Tollens [MT]

 

If p then q

not q

________

not p

 

Here is an example of an argument that has Modus Tollens form:

 

33 McCoy did not know of any such materials. But,  37 if alien materials had been recovered, then McCoy would've known about them.  So, we can be sure that 38no alien materials had been recovered in New Mexico in 1947.*

______________________________________________________________________________________________________

Notes

38.  33,37 MT

 

 

In this example, p = "Alien materials had been recovered," and q = "McCoy knew [ = would've known] about the materials." The argument appears in the text with premises reversed, i.e., as

 

not q

If p then q

________

not p

 

but the form remains Modus Tollens.

 

 

 

5. Complex Modus Tollens [CMT]

 

If p and if q, then r

q

not r

______________

not p

 

Example of an argument that has Complex Modus Tollens form:

 

128 If these men knew about such materials, and if they believed it to be more of a social scientific issue than an issue of national security, then they would've told Jeffrey about the materials. 129 In fact, they must've realized that it was more of a social or scientific issue than one of national security, 130 and, in fact, they did not tell Jeffrey about the recovery of any exotic materials. 131 Therefore, they probably did not know about any such materials.*

_____________________________________________________________________________________________________

Notes

131.  128, 129, 130 CMT

 

 

 

In this example, p = "These men knew about such materials," q = "They believed it to be more of a social scientific issue than an issue of national security", and r = "They would've told Jeffrey about the materials."

 

 

 

6. Hypothetical Syllogism [HS]

 

If p then q

If q then r

_______

If p then r

 

Example of an argument that has Hypothetical Syllogism form:

 

 35 If alien materials had been recovered from a crashed saucer in 1947, then they would have been taken to Wright-Patterson, and  36 if any such alien debris had been taken to Wright-Patterson, then Colonel McCoy, as Chief of Intelligence of AMC would have known about it.  All of this means that 37 if alien materials had been recovered, then McCoy would've known about it.*

_____________________________________________________________________________________________________

Notes

37.  35, 36 HS

 

 

 

 

7. Disjunctive Syllogism [DS]

 

p or q

not-p

_____

q

 

 

8. (one kind of ) Categorical Syllogism [CS]--A, B, and C each stands for a term, not a statement

 

All A are B

All B are C

_________

All A are C

 

Example of an argument that has Categorical Syllogism form:

 

 25 Any flying saucer would be an unimaginably sophisticated flying machine26 Any unimaginably sophisticated flying machine would never crash [i.e. would never be a thing that crashes]  27 Therefore,  a flying saucer would not crash.*

_____________________________________________________________________________________________________

Notes

27.  35, 36 HS

 

 

So, suppose that you want to submit a counterargument against 91 above ("If any flying machine were capable of interstellar travel, then it wouldnt crash"): Fill out the form at the bottom left corner of the book page to get to the submissions page. On the submissions page, there's another form that you can fill in  like this:

 

My suggestion:

 


the following argument should be inserted into the "Roswell" text immediately following statement 95:

96If any flying machine were capable of interstellar travel, then its pilot could make errors. 97But if its pilot could make errors, then the machine could crash. 98So, even if a flying machine were capable of interstellar travel,  it could still crash. [*HS]

 

 

SECOND, you might wish to strengthen a statement that you basically agree with, to make it more convincing or clear.

Suppose you think that statement 91 above could be written more clearly. Fill out the form at the bottom left corner of the book page to get to the submissions page. On the submissions page, there's another form that you can fill in  like this:

 

My suggestion:

 


Statement 91 should be replaced by the following, clearer statement:

91If any flying machine were so technologically sophisticated as to be capable of interstellar travel, then it would be so sophisticated that it could not possibly crash.

 

 

THIS IS THE END OF THE BASIC GUIDE.

THE MASTERSHIP GUIDE STARTS ON THE NEXT PAGE.

 

 

 

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© Richard Crist, 2007