David Hume, suicide and the fallacy of ambiguity

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David Hume

Does Hume commit the fallacy of ambiguity when discussing the arguments against suicide?

In his posthumously published essay "Of Suicide", one of Hume’s arguments for the claim that suicide is not morally wrong goes something like this:

a. It is not morally wrong (a violation of duty) to act according to general law.

b. Acts of suicide accord with general law.

c. Therefore, acts of suicide are not morally wrong (a violation of duty).

His argument for (b) is the observation that "This is what people do -- when distressed and miserable they sometimes commit suicide."  

One might accuse Hume of committing the logical fallacy of ambiguity in the main argument.  This fallacy is committed when a word or phrase has different meanings in two or more propositions.in the same argument (For example: “If all sharp objects are knives and some cheeses are sharp, then some cheeses are knives.”). 

In Hume’s argument the phrase “general law” in premise (a) means a prescriptive law that tells us the conditions under which suicide is morally wrong.  But in premise (b) “general law” refers to a descriptive law that tells us the conditions under which persons are more or less likely to commit suicide.  This ambiguity renders the entire argument invalid. 

In defense of Hume, it might be argued that insufficient attention has been paid to Hume’s claim that the general laws are created by God.  Hence, “it would always be wrong to contravene these laws for the sake of our own happiness. But clearly it is not wrong, since God frequently permits us to contravene these laws, for he does not expect us not to respond to disease or other calamities. Therefore, there is not apparent justification, as Hume put it, for God’s permitting us to 'disturb nature' in some circumstances but not in others. Just as God permits us to divert rivers for irrigation, so too ought he permit us to divert blood from our veins”
 (Cholbi, Stanford Encyclopedia of Philosophy, "Suicide").

[For more on David Hume's essays see my book Understanding David Hume: The Smart Student's Guide to Dialogues Concerning Natural Religion and the essays on Miracles, the Immortality of the Soul and on Suicide. The link takes you to my website.  Once there, scroll to the Hume book cover located below the free book offer.  Click on the book cover.  This will take you to the book's Amazon detail page.]