I Think, Therefore I Know

introspection, evidence

In graduate school, I once took a course on mind-reading. Seriously. But it was a big disappointment. It turns out that what academics mean by ‘mind reading’ is just reading people’s body language. Next time I’ll make sure the course is taught by Professor Xavier of X-Men fame. We are all glad, though, that actual mind-reading (mental telepathy) is currently impossible for humans (as far as we know). I would not want people knowing my inner-most thoughts, nor would I want to know the secret thinkings of others. We enjoy the safety of being able to hide a part of ourselves, only revealing it to those we deem trustworthy. But this means that there is a huge body of knowledge that I alone have access to: my own thoughts! This access comes through something called introspection.

Introspection allows us to access our memories and be aware of the logical progression of our thoughts. It enables us to consider the sensations created by the five senses. Introspection is how we know our reaction to a person’s story–whether we believe it or not, whether it makes us angry or sad. It ties everything together and makes knowledge possible. Philosophers and scientists puzzle over the nature of introspection, but all recognize it’s importance.

Introspection and Faith

religious experience, prayer, evidence, introspection

In other posts, I’ve discussed various kinds of evidence for belief in God. But how can introspection provide evidence? In Christian theism, we believe that God reveals himself, among other means, through a special form of internal communication or awareness. Some, like John Calvin, have called this the “sensus divinitatis.” God, through the presence of the Holy Spirit within us, can “speak”to us, lead us, comfort us, etc. The apostle Paul, in his letter to the Roman church, says that believers are “led by the Spirit of God.” It is the Spirit who “testifies with our spirit that we are children of God.” (8:16) Jesus himself taught that when the Spirit comes to dwell in us, He will “teach you” and “remind you of all the things I told you.” (John 14:26).

This means that we have access to evidence that comes directly into our minds from God, and we access this evidence via introspection. This probably works in the same way as when you suddenly have a new idea, and you reflect on it. But in this case, it is God who forms the idea in your mind, rather than your own cognitive processes. (So mental telepathy IS possible! But only between you and God.) So a Christian may be able to know that God exists and loves her simply by introspecting on evidence conveyed to her internally by the Spirit.

This Sounds Crazy

If you consider yourself a skeptic of Christianity, then this might sound crazy. But this is where you have to distinguish between irrationality and falsehood. Because if there is a God, then there’s no obvious reason why God couldn’t speak to humans in the way I’ve described. The Christian may be factually wrong, but she isn’t being irrational or crazy. To make a “crazy” charge stick, the atheist must show that there is no God, which cannot be done.

Still, I admit it is odd to say, “I know there’s a God because of this voice in my head.” (Though, it isn’t literally a voice.) We would never accept such an argument for any other claim, right? “I know there are aliens/will be an earthquake/Bob is the murderer because of this voice in my head.” So what makes the God case special? 

Here’s one way to think of it. If Bob were the murderer, there’s no reason to expect that I could know this via a “voice” in my head. But if the Christian God did exist, we have good reason to expect that a Christian could know this via a “voice” in her head. In other words, the Christian God (if real) is willing and able to communicate with believers in this way. Admittedly, the case of aliens is more plausible than the murder case. But we still lack good (non-ad hoc) reasons to think aliens would communicate with us in this way. It’s also important to point out that this is not necessarily the way that people initially come to know that God exists. This source of evidence comes into play only after a person comes to believe in the Christian God.

Craig’s Folly?

William Lane Craig has infamously/famously (depending on your viewpoint) said that “the fundamental way in which we know that Christianity is true, including the belief that Jesus rose from the dead, is through the self-authenticating witness of the Holy Spirit.” He goes further to say that the inner witness of the Spirit “can be so powerfully warranted in our lives that it will intrinsically defeat the extrinsic defeaters that the atheists and skeptics bring against it.” In English, what this means is that no matter what evidence is presented to him against Christianity, the inner witness of the Spirit will override all of it. Is this reasonable?

Critics of Christianity go berserk at this point. This sounds like flat-out irrational, blind faith to them. Surely, they reason, there could be evidence that would be sufficient to cause a reasonable person to give up their belief in Christianity. But while I may not necessarily agree with Craig, I think the open-mouthed astonishment at so audacious a claim rests on a misunderstanding. 

Clarifying Craig

The fact is, there are certain beliefs we all hold that are so fundamental to us, no amount of counter-evidence would ever be enough to uproot them. Consider this example from atheist philosopher, William Rowe: 

“Suppose your friends see you off on a flight to Hawaii. Hours after the take-off they learn that your plane has gone down at sea. After a twenty-four hour search, no survivors have been found. Under these circumstances they are rationally justified in believing that you have perished. But it is hardly rational for you to believe this, as you bob up and down in your life vest, wondering why the search planes have failed to spot you.”1

In truth, no matter how much evidence they produce supporting your death, it wouldn’t be enough to convince you. So the idea of a powerfully warranted belief that is immune to counter-evidence is a perfectly coherent notion, common to everyone. And Craig simply argues that the inner witness of the Spirit is just such an indefeasible source of evidence.


So no matter your religious views, there’s no harm in acknowledging the reality of introspective evidence. Such evidence pervades our beliefs–it is indispensable. And even the religious skeptic can concede the following conditional claim: If the Christian God exists, then Christians have introspective evidence of his existence. (In fact, the only way to refute such a claim is to show that God exists, but no such introspective evidence exists!) Still, skeptics can maintain that given atheism, no such non-misleading evidence actually exists! In any case, everyone benefits from reflecting on the role of introspective evidence in their belief system.