C. S. Lewis' Moral Argument

Lewis’s Premise (1): Everyone knows, and so believes, that there are objective moral truths.

Lewis: People blame, praise, and try influence things on the basis of the belief that certain things are really right and wrong – in some objective sense.  And it really is obvious that, e.g., cruelty is wrong.

Objection 1: Many people deny that there is any objective right or wrong.

Lewis: They are always inconsistent in that they go on believing and asserting such that, e.g. some actions are unfair and that there is sometimes such a thing as the “objectively right side” in a war.

Objection 2:  Our sense of morality is just a “herd instinct” that has developed (perhaps by evolution).

Lewis: Morality sometimes commands that we act in accordance with the weaker instinct (e.g. to save a drowning man).  Morality sometimes requires that certain instincts be suppressed or encouraged in a way contrary to our natural impulses.  So it is implausible that morality itself is an “instinct”.

[Note that Lewis is assuming that we are sometimes aware of a conflict between instinct and the Moral Law – and so that the latter is perceived as objective.]

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