The most important questions in life are the big ones. Is there a God? What does it mean to be human? How should we live? What is justice? Big questions tend to have equally big answers – that is, answers that, once understood and accepted, change our lives.

Big questions are not always easy to answer. Why should they be? Just because something is true doesn’t mean it has to be easy to find out or understand – just ask a mathematician or scientist who has sweated blood over figuring out the answer to a tough research problem. Sometimes truth is simple, and sometimes it is complex; like reality itself, at times it is simple on the surface but reveals increasing complexity when examined closely.

So, at times it is a hard slog to find the answers to these big questions – and sometimes the big questions have answers we don’t like, or that we fear we won’t like.

One way to avoid the difficulties (and possibly distressing answers) of a real search for truth is to declare that it is impossible to know anything for sure. It’s very tempting. On the one hand, it’s apparently unanswerable, and on the other hand, it feels intellectually sophisticated. Two for one!

It is indeed possible to doubt everything – even our own existence – and thus avoid addressing questions about ultimate truth. But in the end, radical doubt is a cowardly dodge, because we don’t actually live that way – and we couldn’t even if we wanted to. Let’s consider why that is so.

It is theoretically possible that I, myself, do not actually exist; I might be a brain in a vat, or a character in a super-realistic computer simulation. It is also possible that what I call reality is not real; that the images that I take in of my surroundings only seem like other things and people. Maybe everything is an illusion, and I am just a character in someone else’s dream.

OK, that could be true. However, would you change anything you are going to do today, or next week, or next year based on the idea that you are just a brain in a vat? Or would you carry on doing your laundry, finishing your college degree, and hanging out with your (possibly unreal) friends? 

Consider two possible truth claims: First, that hummingbirds often come to the feeder in my yard. Second, that it is immoral and wrong to murder innocent people. The two claims differ; for instance, we would go about verifying the first claim through observation, and the second through moral reasoning or the application of tradition. It would seem that the second claim is harder to verify than the first, since it is abstract and invisible: perhaps it is only to me, personally, that it seems true that murder is wrong.

However, the radically skeptical position can be applied equally to both. Perhaps I only think murder is wrong because I have been programmed by a computer scientists from Alpha Centauri to think so! Perhaps that hummingbird buzzing around the feeder is not really there, but is just a projection of my brain based on something else. How can I be sure that I am really seeing what I think I’m seeing? Perhaps I only think I see a hummingbird! After all, I am only seeing what my brain presents to me as assembled data taken in by my eyes – how can I be sure that I am seeing anything, much less that I see what I think I see?

To which, at a certain point, we have to just say: Stop!

The fact that I am able to doubt my own perceptions does not mean that my doubts are justified; it simply means that as part of being human, I have the ability to think of counterfactuals: things that are not true, but possibly could be. We use counterfactuals all the time: for instance, when we experience regret or relief over a decision that could have turned out a different way.

In actuality, we do not and cannot act as if there is no truth. We act as if we do know things. I know that other material objects are real, and that my perception of them is accurate – not perfect, since I wear glasses, but generally accurate. When I cross the street, I behave as if the cars were real. If I were to behave according to the belief that the “cars” are just sensory images that impinge upon my neurons, I would come to an abrupt and unpleasant end if I were to step out in front of one of them as I cross the road. And I know that and behave accordingly.

Certainly we cannot know all truth, and we can never know it completely. As each human being is finite, and the amount of true knowledge is infinite (for instance, the amount of true things to know about the past increases with every second that goes by), it is literally impossible to know all true things.

However, such a condition should not paralyze us. Some statements are more important than others. The claim that hummingbirds visit my yard is of localized interest and limited consequence; the claim that murder is wrong is of universal interest and profound consequence.

In real life, we are constantly making decisions about what is important and what is not important, and we make decisions about our beliefs and actions based on the assumption that reality is real and we can know it. We can’t know everything, but we can know some things – or we can at least try to find out the truth about some things as best we can.

In the end, a difference that makes no difference is no difference. If we behave in all aspects of our life as if we existed, and reality is as we perceive it to be, and that we can rely on our senses and the workings of our reason, then it is irrational and inconsistent to backpedal on reality when it comes to matters that impinge on eternity. If the only time that we question reality is when we are confronted with issues regarding morality, obligation, and ultimate truth, but we otherwise are happy to take reality as it comes, then the most logical conclusion is that we just don’t want to face those questions of ultimate truth, and we’re looking for an exit.

Questions about truth can be disconcerting, even frightening – which makes it all the more important to face them with courage and constancy.