David B. Calhoun’s Blog

What is Moorean shift?

Before I discuss my modification (I’m likely not the first to make this modification) to the Moorean shift, I need to explain what exactly this elusive “Moorean shift” is! Simply put, it is when the negation of a conclusion is more certain than the premises for that conclusion. The “shift” is named after common sense philosopher G.E. Moore.

To better understand this, it is best to use an example:

1. A
2. B
3. C
4. Since (A, B, C), therefore P.

(4) in this case is the conclusion, the premises of which are (1-3). But the Moorean shift explains that the belief in not-P is actually more certain than belief in (A, B, C):

1. A < - less certain than not-P.
2. B < - less certain than not-P.
3. C < - less certain than not-P.
4. Since (A, B, C), therefore P.

Simply put, there is something unsound with an argument when the negation of the conclusion is actually more certain than the arguments (premises) for the conclusion!

My modification to the Moorean shift

I agree with this shift principle, and I think it can also be modified to be more broad-ranged. In Epistemology today, I proposed a modification of this Moorean shift:

1. A < - less certain than P.
2. B < - less certain than P.
3. C < - less certain than P.
4. Since (A, B, C), therefore P.

In other words, not only does the shift apply when (A, B, C) are less certain than not-P, but it also applies when (A, B, C) are less certain than simply P. If a conclusion is more certain than its own premises, then something seems unsound with the argument. The purpose of argument is to reason from premises that are more certain than the conclusion - this is the purpose of combining the premises to form the argument for that conclusion. But if the conclusion is already more certain than its own premises, there seems to be no purpose in forming the argument at all.

The purpose of an argument and Dr. Crisp’s comments on my modification

Two things to note here:

1) There again seems to be what I have called teleology (i.e. purpose or end) here. We know that the purpose of an argument is by definition to reason from premises that are going to be more certain than their conclusion. If the conclusion is more certain than its premises, this goes against the purpose of the argument.

2) I proposed this modification to Dr. Crisp and his response was that this seems valid, but he essentially said that it’s not as strong as the Moorean shift. This modification seems to be neutral, he said. I definitely think that the Moorean shift is stronger than my modification of it, since my modification doesn’t involve the denial of the conclusion (P), but I’m not sure what Crisp means when he says that the modification is “neutral”. I think it can still be useful.

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