PHI 220 Symbolic Logic
© 2025 Professor Gary Mar with Haya, Gabriel, Jessica, Yutong
Show
Let =
Yes No
= → ? HINT 2. Use ID
HINT 1. Use CD
Show → Show
Assume (CD) ~ Assume (ID)
Show
HINT 3. Enter PREMISES.
HINT 4. Apply MP, MT,
DN to antecedent lines.
HINT 5. Is ~(→)
as an antecedent line,
Show → . Look at the closest
uncancelled ‘Show’
HINT 6. If → an
unused antecedent line, if have the Box & cancel by CD,
consequent of that citing the consequent
Show ‘Show’ line
if have any
contradiction. Box & cancel by ID,
citing a contradiction
separately, then apply MP.
No Yes
Is the derivation rigorous,
i.e., complete and HALT
correctly annotated? ND
A FLOWCHART FOR CHAPTER 1 DERIVATIONS
© 2025 Professor Gary Mar with Haya, Gabriel, Jessica, Yutong
Show
Let =
Yes No
= → ? HINT 2. Use ID
HINT 1. Use CD
Show → Show
Assume (CD) ~ Assume (ID)
Show
HINT 3. Enter PREMISES.
HINT 4. Apply MP, MT,
DN to antecedent lines.
HINT 5. Is ~(→)
as an antecedent line,
Show → . Look at the closest
uncancelled ‘Show’
HINT 6. If → an
unused antecedent line, if have the Box & cancel by CD,
consequent of that citing the consequent
Show ‘Show’ line
if have any
contradiction. Box & cancel by ID,
citing a contradiction
separately, then apply MP.
No Yes
Is the derivation rigorous,
i.e., complete and HALT
correctly annotated? ND
A FLOWCHART FOR CHAPTER 1 DERIVATIONS
