Chapter One

XKCD on formal logic
Brown Sharpie on philosophy and mathematics

Chapter Two

XKCD on things meta
Logicomix

Chapter Three

SpikedMath on Three Logicians
XKCD on Lojban

Chapter Four

Brown Sharpie on Zeno

Chapter Five

Brown Sharpie on the empty set
XKCD on Polish

Chapter Six

XKCD on tautology

Chapter Seven

XKCD; no pun intended
XKCD; on self-description

Chapter Eight

XKCD on probability
Dinosaur Comics on Hilbert's Hotel
XKCD; on Monty Hall

Chapter Nine

XKCD on truth

Chapter Ten

XKCD on time travel
SpikedMath XKCD
XKCD on arguments

Chapter Eleven

XKCD on knights and knaves
XKCD on explosion

Chapter Twelve

XKCD on Godel
Brown Sharpie on Godel
SpikedMath on Godel
XKCD; on the Halting Problem