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Dissecting Martin Luther’s beer argument- Part 1

15 Jul

Martin Luther and beer

Soon we will celebrate the 500th anniversary of Martin Luther publicizing his 95 ‘bones of contention’ with the prevailing Roman church of the time. Not among them was the following argument, but we can have some fun with this example of Luther’s logic.  Let’s see if it’s sound.

“Whoever drinks beer, he is quick to sleep; whoever sleeps long, does not sin; whoever does not sin, enters Heaven! Thus, let us drink beer!”

To determine if an argument is sound, we must test its validity and truthfulness. On to validity to check if Luther DID construct his argument correctly in how he laid it out.

  • Step # 1 is to ‘translate’ it into logical form.  When we encounter the pronoun ‘whoever’, we substitute the universal quantifier ALL.

P1 – All those who drink beer are those who are quick to sleep

P2 – All those who sleep long are those who do not sin

P3 – All those who do not sin are those who enter Heaven

C – Therefore, all people who drink beer are those who enter Heaven.

Maybe this is the first time you have encountered a chain argument.  Don’t be thrown off by the existence of 3 explicit premises plus the conclusion.

Aristotle never mentioned this argument, although it is named for him.  The Aristotelian or classic ‘Sorites’ is a series of 2 or more syllogisms with accompanying unstated conclusions until the very last one.

Aristotle

Using letters to stand in for the subjects and predicates (what precede and follow the ‘is/are’ in each premise) we get:

P1 – All A is B

P2 – All B is C

P3 – All C is D

Therefore, all A is D

What is missing in THIS case is one implicit conclusion leading to the final one. As logical gals and guys, we have to flush it out.  In general with all sorites we articulate the ‘hidden’ conclusions by extrapolating them through re-ordering two premises at a time in order to create separate syllogisms. In our argument above, there are only 3 premises and you’ll see that we tease them out to form 2 syllogisms

Watch what happens when we switch the position of P1 and P2 and deductively bring to light the hidden conclusion. (Not to worry, we are following a ‘school’ procedure that is perfectly prescribed for just this kind of argument.)

P2 – All B is C  – All those who are quick to sleep are those who do not sin

P1 – All A is B  – All those who drink beer are those who are quick to sleep

C1 -Tf, All A is C  – Therefore, all those who drink beer are those who do not sin (unspoken by Luther)

*

Next we bring down P3 – All C is D  –  All those who do not sin are those who enter heaven

and place underneath it our ‘new’ C1 – All A is C  All those who drink beer are those who do not sin

Following along deductively we arrive at – Therefore, all A is D – Therefore, all those who drink beer are those who enter heaven

and we notice that this latest conclusion, renamed C2 from C1, was the original one in Luther’s argument –  Therefore, all who drink beer are those who enter heaven.

We’ll stop here for this week. The argument IS valid in that the premises and both the extrapolated as well as original conclusions are in the correct form.  Let me know what might still be unclear.  Next time, God willing, we’ll tackle the truthfulness of each premise.  If we determine that the premises are true, it follows that the conclusions must be true because we know the sorites is correctly laid out.  But only if we find all to be true can we THEN conclude that Martin Luther presented a SOUND argument to his beer-swilling buddies!