Save
Upgrade to remove ads
Busy. Please wait.
Log in with Clever
or
show password
Forgot Password?
Don't have an account?  Sign up 
Sign up using Clever
or
Username is available taken
show password


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account. Your email address is only used to allow you to reset your password. See our Privacy Policy and Terms of Service.

Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
focusNode
Didn't know it?
click below
 
Knew it?
click below
Don't Know
Remaining cards (0)
Know
0:00
edit
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

2 Be Logical

INTERMEDIATE logic Lessons 13-15

QuestionAnswer
formal proof of validity a step-by-step deduction of a conclusion from a set or premises, each step being justified by an appropriate basic rule
Formal proofs can only prove VALIDTY; they cannot prove INVALIDITY.
rule of inference a valid argument form which can be used to justify steps in a proof
modus ponens (MP) If p then q; p; therefore q
modus tollens (MT) if p then q; not q; therefore not p
hypothetical syllogism (HS) if p then q; if q then r; therefore if p then r
disjunctive syllogism (DS) p or q; not p; therefore q
constructive dilemma (CD) Both (if p then q) and (if r then s); p v r; therefore q v s
conjunction (Conj) p; q; therefore p and q
absorption (Abs) if p then q; therefore if p then (p and q)
simplification (Simp) p and q; therefore p
addition (Add) p; therefore p v q
Compound propositions of the form "not (p and q) do NOT simplify to not p.
You may NOT skip or combine steps in a proof, even if it seems obvious. You MUST explicitly perform each step AND provide justification for it.
The variables in the rules of inference can represent very complicated compound propositions.
In a proof, different variables in a rule of inference can represent the same or similar propositions.
The variables in the rules of inference may represent different propositions from ONE STEP to the NEXT STEP. That is why they are called variables.
Start a proof by comparing the conclusion with the premises.
Try saying the premises OUT LOUD or in your head to help you recognize which rules of inference to use.
Know ALL of the rules well, but especially learn how to use ABSORPTION and ADDITION.
Created by: MrsHough
Popular Social Studies sets

 

 



Voices

Use these flashcards to help memorize information. Look at the large card and try to recall what is on the other side. Then click the card to flip it. If you knew the answer, click the green Know box. Otherwise, click the red Don't know box.

When you've placed seven or more cards in the Don't know box, click "retry" to try those cards again.

If you've accidentally put the card in the wrong box, just click on the card to take it out of the box.

You can also use your keyboard to move the cards as follows:

If you are logged in to your account, this website will remember which cards you know and don't know so that they are in the same box the next time you log in.

When you need a break, try one of the other activities listed below the flashcards like Matching, Snowman, or Hungry Bug. Although it may feel like you're playing a game, your brain is still making more connections with the information to help you out.

To see how well you know the information, try the Quiz or Test activity.

Pass complete!
"Know" box contains:
Time elapsed:
Retries:
restart all cards