INCLUSIVE OR EXCLUSIVE
On the main page about deductive reasoning, an example is given:
Major Premise - Everyone who eats cheese puffs is a computer programmer.
Minor Premise - Alley eats cheese puffs.
Conclusion - Therefore, Alley is a computer programmer.
Notice the construction of the first statement: Everyone who eats cheese puffs is a computer programmer. When attempting to build a premise, ask yourself a few questions -
Is the premise testable? In the above case, can one realistically poll the entire intersection of the set of people who eat cheese puffs and computer programmers? Not really. If you can’t reasonably test your premise, either rebuild it or abandon it.
INCLUSIVE OR EXCLUSIVE
I like to think of premises as inclusive and exclusive. The above is what can be called inclusive. In this case, everyone in set (A), cheese puff eaters, is included in set (B), computer programmers.
(A & B)
If we re-worded it to say “No computer programmers eat cheese puffs,” we are saying that a person can be in set (A), cheese puff eaters, OR set (B), computer programmers. There is absolutely no overlap.
(A) or (B)
KEEP THE SETS SMALL
When building premises this way, try to keep the sets as small as possible. Let’s say you are trying to figure out who at work ate your lunch. You start with the set of people who were in the building between the time you put it in the refrigerator and the time you came back. That’s likely a fairly small set. Then you can check people’s calendars for meetings, conference calls, etc. If they were occupied during the time the issue occurred, you can de-prioritize them.
The major premise is : Whoever took my lunch had to have been in proximity of the refrigerator.
The minor premise is : Bill or Joan or whoever was known to be in another location at the time in question.
The conclusion is that since the person couldn’t have physically accessed the fridge, they could not have stolen the lunch.
You would use a set of premises to form the shortest list possible, then go check their trash cans for the evidence.
In conclusion, remember: only use testable premises, try to keep the data sets as small as possible, and don’t cling to a premise once you realize it is faulty.
CONCLUSION & APPLICATIONS
In conclusion, remember: only use testable premises, try to keep the data sets as small as possible, and don’t cling to a premise once you realize it is faulty. Here are some small ways that you can use this information: