I've been a scientist for as long as I can remember. Children are born scientists; they experiment with everything, are naturally inquisitive and through this exploration they learn about how the world works. And I've never grown out of it. Of course, for many people, their modes of thought change as they find or are brought up with faith. Some manage, somehow, to hold religious beliefs alongside a dedication to the rationality of science.

I had a brief flirtation with Christianity in my teens, probably as a form of rebellion against my nuclear physicist father. But ultimately I could never reconcile what I saw as a contradiction between the principles of the scientific method and faith in a supernatural god. And ever since then, it has puzzled me how anyone could be religious whilst also being a scientist. How can one hold what I saw as diametrically opposed belief systems? How, on the one hand, could someone devote themselves to the scientific methods where, through repeated experimentation, one builds up a self-consistent representation of the rules that govern the universe, whilst on the other hand believing in a force that existed outside the rules and that, indeed, could change those rules.

Working in a university, I'm surrounded by scientists, and many of the best of them have religious faith. I've discussed these apparent contradictions of faith and science with some of these colleagues. I fully expected to hear arguments such as deism, where a god started the universe off but hasn't intervened since then. Or maybe theistic evolution, with their god directing the evolution of the Universe and life within it. And indeed some did have these stances. But many of those I spoke to also took a literal interpretation of miracles from their holy texts. Which took me back to square one. If a god can change the rules of life, then how can you believe the rules governing your experiments won't change from one day to the next? And it always came down to the fact that they just had faith in the scriptures, which left me feeling rather dissatisfied.

Ultimately faith is the knowledge that something is true even through there is not evidence to support it, whilst science is the belief that something is probably true because of a body of evidence that supports a theory. I thought you had to choose a side.

Then I started to dabble in the philosophy of science and the history of scientific reasoning. I read about Francis Bacon and his book Novum Organum (published in 1620) which set out the principles of experimental science that we still use today. Prior to this, enquiry largely followed deductive reasoning. In Novum Organum (which translates as The New Method) Bacon argued that deductive reasoning should replace inductive thought.

"There are and can be only two ways of searching into and discovering truth. The one flies from the senses and particulars to the most general axioms, and from these principles, the truth of which it takes for settled and immoveable, proceeds to judgment and to the discovery of middle axioms. And this way is now in fashion. The other derives axioms from the senses and particulars, rising by a gradual and unbroken ascent, so that it arrives at the most general axioms last of all. This is the true way, but as yet untried."

Deduction starts with statements or hypothesis and then explores what logically follows from these before making predictions. For example, if we take the two statements "eggs go rotten after their use-by date" and "this egg is past its use-by date", then we can deduce that this egg is rotten. For the deduction to be sound, then the starting statements must be true. This means that deduction limits the generation of new knowledge because you can only follow from what is already known. That’s not to say you can’t make significant progress with deduction, just that it has inherent limitations.

Induction holds that by making observations we can discern patterns before making predictions about the future. For example, if you observe that the first 11 eggs in a dozen are rotten then you can induce that the 12th egg in the box is also bad. Induction isn't as rigorous as deduction, you can't be sure of the state of the egg until you actually break it open. But, induction does have one massive advantage as it allows you to generate new knowledge without having to know anything before hand. In this example, you can be pretty sure that serving the 12th egg isn’t a good idea, even without knowing anything about the shelf life of eggs. In contrast, to deduce that the egg is rotten you need to have factual statements to base your reasoning on (as given above).

Its not just scientists (or short order chefs) that use induction, it's actually fundamental to our decision-making processes. Almost everything we do on a daily bases is derived from past experience and a body of collected observations. For example, every time you drive a car you are using inductive reasoning; when you hit the brakes you are sure that the car will slow down. But why are you confident this will happen? Quite simply because every other time you've hit that pedal, the car decelerated, and because you've had the car serviced recently.

But there's a logical problem with inductive reasoning, which was highlighted by the 18th Century philosopher David Hume. He asked why induction was justifiable. What evidence do we have that it works? The obvious answer to this is that it has always worked in the past; induction is central to the development of science, which has developed all the technology of the modern world, and our daily lives are predicated on it. But that's a circular argument; its using inductive reasoning to argue for inductive reasoning. Hume's problem still vexes philosophers to this day.

So what have these explorations in the philosophy of science got to do with my attempts to understand how people can reconcile a faith in religion and evidence-based science? Basically, there's no single logical explanation for why induction works: it just does. Which means I'm left with the belief that induction works without the sound evidence to support it, i.e. I have faith in the scientific method. This realisation made me stop worrying about how people can hold religious faith and scientific beliefs simultaneously. It demonstrated to me that faith and evidence-based beliefs coexist in my mind, so in a way, I am no different from my fellow scientists who have faith in the miracles of theologies. This realisation has made me no more inclined to believe in a god. But it has given me a better understanding of religious beliefs by demonstrating that, without ever realising it, I too have a deeply-seated faith in my own (scientific) belief system.