Leibniz and innatism

What is a necessary truth?

- True in all possible worlds- cannot not be true. (in which they exist at all).
- To deny a necessary truth would involve some self-contradiction.
- Cannot be known by observation/experience.

What is a contingent truth?

- Only true in some possible worlds.
- Could be false, at least in some possible worlds.
- To deny a contingent truth involves no self-contradiction.
- Can be known by observation/experience.

What does Leibniz claim about observation and necessary truths? What does he conclude from this?

- Observation does not establish necessary truths because observation gives us instances of a truth in a particular universe. However, necessary truths have to be true for all time and in all possible universes. Observation cannot reach to all times and all possible universes.

- Necessary truths must be innate

Express this as a stepped arg.

R1: The senses only give us particular instances.
R2: A collection of instances can never show the necessity of a truth.
R3: We can grasp and prove many necessary truths (in maths, geometry, logic).
IC1: Therefore, the necessary truths that we grasp with our mind do not derive from our senses.
IC2: The mind is the source of these necessary truths.
C: These ideas are known innately.

How might people initially respond to this arg?

The stepped argument he has just formed has taught them about necessary truths and for that reason their ideas and knowledge about necessary truths must be acquired, and not innate.

What analogy does Leibniz offer in response to this?

Leibniz saw innate ideas/knowledge as equivalent to a statue carved from marble. The statue/idea is in the block of marble/mind; however, it needs to be carved/drawn out by the chisel/experience.

What is the first issue with Leibniz's necessary truths arg?

you might wonder whether the difference between innate and acquired ideas has been sufficiently marked. What is the difference between an innate and an acquired idea given that innate ideas have to be uncovered. To the person becoming aware of them, they look exactly the same. Wouldn't it be simpler to say there are only acquired ideas.- Ockham's razor?

What is the second issue with Leibniz's necessary truths arg?

Perhaps innate concepts/knowledge are acquired conceptual, analytic, truths. An analytical truth is one which is true by definition. By acquiring language we learn that the words used for certain concepts (ideas) are related to each other, such that if you know the definition of words X and Y, you understand X's definition contains word Y. You can then know truths about the relationship of X to Y. If necessary, truths were analytic and conceptual we could, as a result, understand how we grasp them without confirmation from repeated experience, and, yet understand that they are acquired by experience, through language acquisition, and are not innate.

How does Leibniz reply?

Leibniz will argue that explaining the rapid way in which we acquire necessary truths by language acquisition will not explain the necessity of these truths. If we learn necessary truths through language acquisition, we expect to only learn truths which hold in this possible world, not in all possible worlds.