The petty thief’s fallacy
Little Timmy likes cake. Mmm.
Have you come across the petty thief’s fallacy? It takes the following form.
- It is wrong to breach principle P
- Person B breaks principle P to a small degree
- Therefore, person B has not acted wrongly
An example. Mother has just finished baking and icing a chocolate cake. She says to little Timmy, ‘Timmy, you are not to eat any of this delicious chocolate cake’. But then little Timmy thinks, ‘But if I only eat a small slice, it won’t be so bad. There’s lots of chocolate cake and I only want a small piece. There will be plenty of cake left over if I only take a small slice’. So little Timmy cuts himself a very small slice of cake and eats it. Mmm, that delicious chocolate cake. Here’s little Timmy’s reasoning:
- Mother said it is wrong to eat any of the chocolate cake
- I’ll only eat a small slice of the chocolate cake
- Therefore, it’s okay for me to eat a small slice of the chocolate cake
But little Timmy’s reasoning is fallacious because he mistakenly thinks that the magnitude of his infraction matters — that it’s okay if he only takes a small slice of chocolate cake. Little Timmy’s fallacy turns on his belief that taking a small slice of the cake only constitutes a small breach of Mother’s orders. But any breach of Mother’s orders, large or small, is a breach of Mother’s orders. The magnitude of the breach does not matter.
Now, little Timmy’s fallacious reasoning is often used when it comes to breaches of privacy or property, as follows.
- It is wrong to invade someone’s privacy without just cause
- Person B ever so slightly breaches someone’s privacy without just cause
- Therefore, person B has not acted wrongly
For example, you walk into a room and there’s a diary open on a desk. Reading the diary constitutes a breach of privacy, and according to (1) you cannot breach privacy without just cause. But you really want to read the diary, so you say to yourself, ‘I’ll only read the pages that lie open; it’s not like I’ll read the dairy cover to cover’. But the reasoning is fallacious. Any attempt to read the diary is a breach of privacy.
You may fell the need to read parts of the diary in order to find who the owner is and return it to them. But this would constitute ‘just cause’ for breaching privacy, and so would not be a breach of (1).
Here’s another example, applied to property.
- It is wrong to steal without just cause
- Person B takes Person C’s packet of matches without just cause
- Therefore, person B has not acted wrongly
A packet of matches is pretty insignificant, but that doesn’t change the fact that taking the matches constitutes theft. Here is where it gets interesting, however. Let’s change the scenario a little. Let’s look at the fallacious reasoning from the point of view of the person whose property has been stolen. What is an appropriate response by person C?
C may think, ‘It’s only a packet of matches, who really cares that they’ve been stolen’. But, given (1) and the fact that the magnitude of a breach of (1) doesn’t matter, if C adopts this response then C can not adopt a different response when B steals something significant. That is, if C doesn’t care when B makes a small infraction of the principle, then how can they adopt a different position towards a greater infraction? They can’t; at least they can’t adopt different responses to breaches of different magnitude and remain consistent.
The principle is worth upholding or it is not. If it is worth upholding then the magnitude of any breach of the principle does not matter. But if person C takes into account the magnitude of a breach when considering whether to uphold the principle, then they commit the same fallacious reasoning as the petty thief. In essence, they wrongly believe that the magnitude of a breach of the principle matters.
So, where are we? Well, we can conclude that if it is wrong to steal without just cause then the magnitude of a breach does not alter the rightness or wrongness of that breach. Furthermore, the magnitude of a breach cannot influence our response to a breach. If it is wrong to steal without just cause and we ignore a small infraction of the principle then we cannot complain when there are large infractions. Why? Because that would imply that the magnitude of the infraction matters.
Category: Philosophical Analysis | Tags: logical fallacy 6 comments »
December 17th, 2010 at 11:04 am
There is at least one non-trivial problem with how I’ve set out the argument. If you can find it, you can have a piece of chocolate cake.
December 17th, 2010 at 11:58 am
I think it comes down to how the principle is stated; one could restate it in a way that is not a fallacy by taking consequences into account.
The new version of your original form (with my charges highlighted) would then be:
1.It is wrong to breach principle P [if there are significant negative consequences]
2.Person B breaks principle P [with no significant negative consequences]
3.Therefore, person B has not acted wrongly
I think that gets around the problem; if the person/organistion/society wronged considers the breach to be trivial, then they can let the person off without punishment while still maintaining the principle in the case of non-trivial infractions.
I could be wrong, as I have little to no training in logical arguments, but that is my take.
December 17th, 2010 at 2:05 pm
I think that clears it up nicely Jason.
December 17th, 2010 at 2:13 pm
Jason, you’re quite close. The mistake or oversight in my reasoning does have to do with consequences. Here’s what I had in mind, specifically.
I included the clause ‘without just cause’ in the later examples because to omit it would imply that it is never right to breach a principle. This seems silly. There may, at times, be very good reasons for breaching a principle. Including the clause allows for such occasions, so long as there is a good reason for the breach — i.e. just cause.
But if I include this clause in the later examples, I should also include it in the first example of little Timmy and the chocolate cake. Accordingly, the argument becomes:
1. Mother said it is wrong to eat any of the chocolate cake
2. And it is wrong to breach Mother’s orders without just cause
3. I’ll only eat a small slice of the chocolate cake
4. Therefore, it’s okay for me to eat a small slice of the chocolate cake
The important question becomes: ‘Does (3) constitute just cause?’ If yes, then it is okay for little Timmy to eat the cake. Now, the pettiness of the transgression does not by itself constitute just cause. If so, then no principle would hold at the level of minor infraction. One could breach any principle if one only did so in a small way. I could always take a little slice of cake; could always invade people’s privacy ever so slightly; could always commit petty crime. But if (3) became ‘If I don’t eat a slice of this chocolate cake I’ll die’, then little Timmy might have just cause for eating a slice. Hell, he might even have just cause to eat the whole thing!
And this is the next question. If little Timmy is starving, thereby giving him just cause to infract Mother’s order, is he thereby within his rights to eat the entire cake? The answer seems to turn on what he needs to avoid starving to death. If little Timmy only needs a slice to prevent his imminent death by starvation, then his ‘just cause’ only covers that amount of cake. Beyond that, he’s breaching Mother’s order without just cause.
This has implications for my later argument that we cannot complain about large infractions of principles if we do not complain about small infractions. It’s now apparent, given the revision to the case of little Timmy, that in some instances we may be able to complain about major infractions when we didn’t complain about minor infractions. If little Timmy has just cause for committing a minor infraction (eating a slice of cake) but not for a major infraction (eating the whole cake), then we can complain when he commits the major infraction even though we didn’t complain when he committed the minor infraction. But this all depends on little Timmy having just cause and that just cause extending only to a minor infraction. It does not simply depend on the magnitude of the infraction. It just so happens that a small infraction is that sized infraction which little Timmy has just cause to commit.
So, it seems that there are cases in which we can legitimately complain about a major infraction of a principle even though we didn’t complain about a minor infraction of the same principle.
There is one other option. One could simply say that little Timmy never has just cause to disobey Mother’s orders; that is, we could adopt the idea that one is never justified in breaching a principle. And your suggestion seems a reasonable response to this position.
You can have a small piece of cake.
December 20th, 2010 at 1:21 pm
Dylan, I feel you should clarify to Jason what constitutes a small piece of cake? Having a passion for mathematics, I generally find expressing things in fractions a suitable resolve when faced with such explanations.
December 20th, 2010 at 2:17 pm
1/16 ≡ small piece of cake