Hume's Law

I think I’ve finally settled on a position in regard to Hume’s Law.  There is a version of it that is true, but it has much less import than many philosophers seem to think.  The version that I affirm is weak.  It can’t do the work that many wish it to do - it can’t be used to support non-cognitivism, nor the fact-value distinction, at least insofar as that distinction tries to banish values from the realm of fact.

I think, along with Pigden, that Hume’s Law is an instance of the more general logical principle that one cannot “get out” of a conclusion what one has not put into the premises.  If there is no normative content in a premise, then the conclusion will have no normative import.  

So yes, one can indeed not move from purely descriptive premises to a normative conclusion. This requires the natural lawyer to employ the use of Bridge Principles, to move between descriptions of what constitutes human flourishing to normative claims that we ought to support human flourishing.  Murphy’s Real Identity Thesis and Oderberg’s belief that nature has built-in normativity or values are examples of such bridge principles.  The New Natural Lawyers tend to affirm Hume’s Law.  Robert P. George and Patrick Lee both affirm it, for instance. Plus Mark Murphy’s use of the Real Identity Thesis seems predicated on the truth of this version of Hume’s Law and seems to be offered as a bridge principle to cross the fork. 

But there’s a stronger version of Hume’s Law, one that many believe supports non-cognitivism, banishing values and normativity from the realm of fact entirely.  The philosopher Russ Shafer-Landau provides a relatively common formulation:  

When we describe the world, we talk about what is the case.  But morality speaks of what ought to be the case.  How can we get from descriptions to prescriptions?  How does knowing how the world actually works enable us to learn how it ought to work?  Hume thought that there was no answer to this question.  If he is right, there is a gap between what is and what ought to be, a gap that can never be crossed.

So we can distinguish two versions of Hume’s Law:

Weak Version:  You can’t derive an ‘ought’ from purely descriptive premises.

Strong Version: You can’t derive an ‘ought’ from any descriptive premises.

The Strong Version seems to be false.  Here’s a counter-example to it:  “There is an obligation.”  This is a descriptive statement, for it’s describing what there is.  And from this descriptive statement, I can infer that I ought to do something. So, contra Hume’s Law as described by Shafer-Landau, we can indeed move between ‘knowing how the world works’ to ‘how it ought to work.’ So I can indeed derive an ‘ought’ from an ‘is.’  And here’s the thing:  If moral realism is right, then something like this descriptive statement is true.  If there are no statements like this that are true, then moral realism is false.

Again, if the Strong Version of Hume’s Law is right, then you cannot derive an ought from any descriptive premise, including the one just given.  But that seems clearly false with this example.  Why? Due to normative entanglement.  Though the statement is descriptive, it contains a normative element.  And since the normative element has been “put in,” you can get it out with the conclusion.