I call upon You, Lord, God of Abraham and God of Isaac and God of Jacob and Israel, You who are the Father of our Lord Jesus Christ, the God who, through the abundance of your mercy, was well-pleased towards us so that we may know You, who made heaven and earth, who rules over all, You who are the one and the true God, above whom there is no other God; You who, by our Lord Jesus Christ gave us the gift of the Holy Spirit, give to every one who reads this writing to know You, that You alone are God, to be strengthened in You, and to avoid every heretical and godless and impious teaching.

St Irenaeus of Lyons, Against the Heresies 3:6:4

Sunday, January 31, 2010

Right Reasoning, pt. IV, The Hypothetical Syllogism

Yet another valid form of Right Reasoning...

IV. The Hypothetical Syllogism

A. Formally stated:

1. If P, then Q;
2. If Q, then R;
3. If R, then S,
4. Therefore, if P, then S

B. 1. Illustrated from epistemology:

i. If (P) knowledge is possible, then (Q) truth exists.

ii. If (Q) truth exists [and truth is absolute], then (R) truth requires an absolute mind [since truth is absolute and is mental activity].

iii. If (R) truth requires an absolute mind, then (S) knowledge is dependant on an absolute-personal being [since mind is a property of persons].

iv. Therefore, if (P) knowledge is possible, then (S) knowledge is dependant on an absolute-personal being, and that being can only be the God of Christian theism.

B. 2. Illustrated from (anti-) ethics:

i. If (P) Naturalism is true, then (Q) then nothing exists beyond natural phenomena.

ii. If (Q) nothing exists beyond natural phenomenon, then (R) morality must have its basis in natural phenomena.

iii. If (R) morality must have its basis in natural phenomena, then (S) scientific investigation is the only method of detecting morals.

iv. If (S) scientific investigation is the proper method for detecting morals, then (T) we’re left with only descriptions [i.e., “what is the case”], never prescriptions of behavior [i.e., “what ought to be the case”].

v. If (T) we’re left with only descriptions of behavior, never prescriptions [and we can’t move from “is” to “ought” – Hume], then (U) morality is impossible.

vi. If (U) morality is impossible, then (V) there is no morally significant reason one ought to believe anything at all.

vii. Therefore, if (P) Naturalism is true, then (V) no one ought to believe it.

C. Fallacy factor:

With the hypothetical syllogism, we risk postulating relations between antecedent (the “if” clause) and consequent (the “then” clause) that either are not obvious or not there at all. In fact, the hypothetical syllogism is most helpful for demonstrating the truth of more general propositions, such as, “There is no reason to believe Naturalism,” through a chain of causal or logical relations.

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