PHLA10 Reason and Truth
Exercise 2
1. Here's a little logical puzzle: you are in a strange land where everyone is either a knight or a
knave. Knights always tell the truth; knaves always lie. You meet two of them, A and B. A says
"we are both knaves". What are A and B? Prove it.
The A cannot be a knight. Knights always tell the truth, so if he were a knight, he would tell you
so. Instead, he says, "we are both knaves." If the A is a knave, then he must be a liar. This means
they cannot both be knaves. So, since we have established that the A is a knave and a liar, the B
must be a knight.
2. What are the four main characteristics of God as Aquinas understood it?
The four main characteristics of God as Aquinas understood as “personal”, “omnipotent” ,
“omniscient” and “omni-benevolent”.
3. Explain why the "Birthday Fallacy" is a fallacy.
4.
5. What is "backward (in time) causation"? How would it affect Aquinas's first two arguments for
God's existence?
Backwards causation is a concept of cause and effect in which an effect precedes its cause in time
and so a later event affects an earlier one. If we push backwards far enough, we find that the
universe reaches a state of compression where the density and gravitational force are infinite.
This unique singularity constitutes the beginning of the universe—of matter, energy, space, time,
and all physical laws. The idea of gravity defies the argument of motion and every change in
motion of a body requires a cause. Thus backward causation counter argues Aquina’s first two
argument for god existence.
6. What is the difference between necessity and contingency?
Necessity is a proposition that could not possibly have been false. This can be expressed by
saying that a necessary truth is a proposition that is true in every possible world. Contingencay is
a proposition that is not necessarily true or necessarily false. A contingent truth is a true
proposition that could have been false; a contingent falsehood is a false proposition that could
have been true. This is sometimes expressed by saying that a contingent proposition is one that is
true in some possible worlds and not in others.
Exercise 2
1. Here's a little logical puzzle: you are in a strange land where everyone is either a knight or a
knave. Knights always tell the truth; knaves always lie. You meet two of them, A and B. A says
"we are both knaves". What are A and B? Prove it.
The A cannot be a knight. Knights always tell the truth, so if he were a knight, he would tell you
so. Instead, he says, "we are both knaves." If the A is a knave, then he must be a liar. This means
they cannot both be knaves. So, since we have established that the A is a knave and a liar, the B
must be a knight.
2. What are the four main characteristics of God as Aquinas understood it?
The four main characteristics of God as Aquinas understood as “personal”, “omnipotent” ,
“omniscient” and “omni-benevolent”.
3. Explain why the "Birthday Fallacy" is a fallacy.
4.
5. What is "backward (in time) causation"? How would it affect Aquinas's first two arguments for
God's existence?
Backwards causation is a concept of cause and effect in which an effect precedes its cause in time
and so a later event affects an earlier one. If we push backwards far enough, we find that the
universe reaches a state of compression where the density and gravitational force are infinite.
This unique singularity constitutes the beginning of the universe—of matter, energy, space, time,
and all physical laws. The idea of gravity defies the argument of motion and every change in
motion of a body requires a cause. Thus backward causation counter argues Aquina’s first two
argument for god existence.
6. What is the difference between necessity and contingency?
Necessity is a proposition that could not possibly have been false. This can be expressed by
saying that a necessary truth is a proposition that is true in every possible world. Contingencay is
a proposition that is not necessarily true or necessarily false. A contingent truth is a true
proposition that could have been false; a contingent falsehood is a false proposition that could
have been true. This is sometimes expressed by saying that a contingent proposition is one that is
true in some possible worlds and not in others.
