LCA – Points 2 to 4

In our previous post on Leibniz’ Cosmological Argument, we examined the first premise, the PSR. I would summarize the PSR with the claim “reality is fundamentally intelligible”, though we go into more technical detail in that previous post. To remind you, here is the full argument:

  1. Every contingent fact has an explanation.
  2. There is a contingent fact that includes all other contingent facts.
  3. Therefore, there is an explanation of this fact.
  4. This explanation must involve a necessary object.
  5. This necessary object is God.

Here we will examine points 2 to 4. These are reasonably simple, and although they are sometimes disputed there shouldn’t be anything too controversial here. Most skeptics who deny this argument will take issue with premises 1 or 5.

(2)               There is a contingent fact that includes all other contingent facts.

It is at this point that we must define what a “contingent” fact is. Briefly, a contingent fact is a fact that does not explain itself. For example, we might say “a cat exists”. Is that self-explanatory? Can we coherently ask “why does a cat exist?”. In the case of my cat, explanations may include: me and my brother asked my parents for one, and also the cat has parents, and also the cat is composed of molecules, and also the species “cat” evolved. These are all partial explanations for the contingent fact “my cat exists”. Here, a contingent fact is any fact like this, any fact X that has an explanation Y, where Y and X are not identical.

This definition is a bit vague, and purposefully so. There are multiple conceptions of precisely how we cash out contingency, and I want my argument to be general enough to cover all of them. But if you are after a more specific definition, try this one: a contingent fact is a fact that is true in some possible worlds, but not all possible worlds. There are some worlds in which there is no cat (or no matter), and some that include a cat. Note that I am not talking about a multiverse here, some worlds contain one universe, some contain multiple, some contain none. A possible world is a way that reality could have logically possibly been, but isn’t. A possible state of affairs that could have attained, but didn’t. If this is a new idea for you, perhaps study this SEP article. We will occasionally make use of this definition during our argument, but I will attempt to stay as general as possible.

Some of you are necessitarians and reject possible worlds. I am. If that is you, then we will need a different notion of contingency. I intend to publish my thoughts on that once we have completed the entire LCA series.

The actual premise is relatively easy. If it’s true that “x is a fact” and “y is a fact”, then it’s true that “both x and y are facts”. So we can construct a true statement such as “x is a fact and y is a fact and……..” and so on until we’ve covered every contingent fact. This fact that we’ve constructed is contingent because all of the incorporated facts are contingent. If any of them could possibly be different, then so could the constructed fact. In some other literature, this fact is called the BCCF (Big Collected Contingent Fact).

There is a minor concern here that the BCCF could be self-referent. That is, the BCCF includes the BCCF . Some of you will be familiar with Russel’s Paradox, which relies on this kind of self-reference. So there are two solutions, I think either works. Either we say that this isn’t a set, and we call it a “collection” or something, and then we aren’t bothered by self-reference. Or we construct the BCCF by including every contingent fact that isn’t the BCCF, we include every other contingent fact. This is a relatively minor issue, it is in a sense just nitpicking. But it seems important to include it so people don’t get grumpy at me.


(3)               Therefore, there is an explanation of this fact.

This follows from (1) and (2). Every contingent fact has an explanation due to the PSR, so the fact we just constructed has an explanation

(4)               This explanation must involve a necessary object.

Let’s suppose it isn’t true, suppose the BCCF is explained by a contingent fact. Given the PSR, then this explanation still has to exist. We’re supposing it’s not necessary, which means it must be contingent. But if it’s contingent, then it’s part of the fact that we’re trying to explain.

This means that the explanation is its own explanation. It doesn’t depend on anything else to be true. This means it’s not contingent, and is instead necessary. So by reductio, the explanation for the constructed contingent fact must be necessary.

Some complain that I’ve equivocated between “fact” and “object” here. But this is not a big problem, like the self-reference above. Every fact refers to at least one object, and for every object X we have the fact “X exists”. We can travel between “facts” and “objects” freely. I choose the term which best primes the intuition of the person reading it.

This will conclude the middle section of the LCA. Next time, we will investigate what the necessary explanation is, we will work out what properties and attributes it must have, and end up concluding that it is God.