phi202

Hume

Positivist Verification Principle

If a statement is cognitively meaningful, i.e has a truth value, is truth evaluable, then it falls into one of two categories.

First category:

Empirical Statements

Observationally definable. True at some and false at others.

Positivist assumes that any two different worlds differ in terms of some observation you'd make if you lived there.

These are empirically verifiable, which means that the truth of certain observation statements would render it true.

Also, its being true or false makes a difference to observation.

Second Category:

Analogically true or false statements

These are ones whose truth or falsity is provable by pure logic. If logically true it's true no matter what observations you'd make logically false it's false no matter what observations you make.

The truth or falsity of empirical claims follows by reason from observation

The truth or falsity of non-empirical but meaningful claims follows by logic/reason a lone

All claims that are genuinely true or false fall into one of these categories

Relation to morality:

Positivists hold that moral statements are not truth evaluable, being expressions or prescriptions rather than descriptions. So they don't have to follow from observations via logic or from logic alone. Hume argues a similar sort of view. But he argues in the opposite direction. Instead of starting from lack of truth value and saying that therefore the moral statements aren't provable in these ways, he tries to show independently that the moral statements aren't provably in these two ways and argues from that they mustn't be genuine factually claims, but merely expressions of sentiments. Instead of describing the two categories of truths as empirical analytic, he describes them as truth of experience and matters of fact (provable from observation, using logic) vs truths of reason, relations of ideas (provable by logic alone)

Hume takes examples of moral claims and challenges us to prove them either of these two ways. He claims we can't. See page 3.1.4 of The principles of Morals

p.287

at line 337 he considers the possibility of an argument from facts of experience. If there is such an argument it must derive from the whole of the circumstances involved. Those circumstances give rise to us a certain sentiment. This sentiment is contingent and arbitrary, thus, there is no logical requirement for that sentiment to arise in us.

One can be rational and be aware of the facts and fail to feel the moral response. So you can't using logic derive the moral disapproval from the observational facts. (note here the modern era assumption that you aren't illogical if you are a mad scientist who sees the world happy and wants to break it - you are evil, nasty, weird but not necessarily irrational.)

All the more you can't derive the moral response from pure reason. For Hume, the moral response is rationally arbitrary and is a species of animal sympathy.