Reason alone is incapable of rationally justifying its own existence

fractals in nature

People are committed to basic beliefs (called presuppositions) which they have not necessarily proven, and yet they interpret all of reality in terms of those presuppositions. They cannot function in this world without first assuming these basic beliefs.

This article examines elementary beliefs in general that are the foundation of science. It then moves into perhaps the most important — and what some of the greatest philosophical minds in history have concluded regarding its validity.

The universality of the laws of logic is one general belief people take for granted. Is logic the same regardless of who is using it? Do the laws of logic remain the same across cultures? Do the laws of logic operate the same millions of light years away in some remote corner of the universe as they do here on earth? Did they operate the same in the past as they will in the future?

Most people assume the answer to these questions is Yes. If you ask them why, they will probably come up short on reasons. For as enlightened as modern society claims to be, most people haven’t even thought about these questions. “It has to be that way, or nothing makes sense.” That’s certainly true, but to state it as your reason for believing is barely more than an arbitrary assumption which violates what we call the tenets of “rational thinking.”

Another fundamental belief that gives philosophers problems, but which people simply take for granted, is the uniformity of nature: on what basis can we rationally expect the universe (things like physical cause-and-effect) to behave the same in the future as they have in the past? Why should the earth continue its revolution around the sun tomorrow as it has for thousands of years in the past? Why should the “laws of gravity” not fail us tomorrow?

These are metaphysical questions because they inquire into the nature of reality and man’s mind in relation to it.


David Hume was a brilliant philosopher of the 18th century. He raised these issues in his investigation of the problem of inductive reasoning. But, informing his investigation, was a fundamental (unstated but implied, as far as I know) presupposition which would have guided his studies: that everything in the universe is inherently unconnected. Any “connection” that appears to exist is of human convention. Merely thinking that you recognize a pattern between cause-and-effect makes it so.

Since things are inherently unconnected, the mind cannot know anything except what is present with it at any given moment — sense data. The supposition of a connection between cause-and-effect has no foundation in reasoning. Rather, our mind fills in the gaps by imagining the stuff we can’t see — stuff like the very concept of “cause-and-effect”. He said it’s not logical, but rather psychological, that we make such an intellectual leap. Since there is no underlying meaning, no underlying metaphysical form connecting anything in the universe, we all simply create our own realities through the creative powers of our imagination. This philosophical view is known as nominalism.


Nominalism is the theory that no such things as abstract entities or immaterial concepts like classes or the laws of logic exist, only people. If we put our hand to a hot stove and withdraw it in pain and yell “Ouch!”, it’s not because the stove was so hot that it stimulated reflexes in our body; rather, it was just our minds imagining such a connection. There was no real connection between the events. We could have just as easily yelled “That feels great!” and seen chickens. We couldn’t even say the stove was “hot,” just that we touched it. What we felt was all imagined in our brains.

In the language of the philosophers, Hume argued that a priori knowledge is a requirement to develop a posteriori knowledge, but discovered that a priori knowledge can only be derived from a posteriori knowledge. So, he identified a circularity in man’s reasoning from which there is no escape.


Hume’s problem is ultimately the one of the many. How many realms or modes of reality are there? The implications of his metaphysical presuppositions are that there are an infinite number: as many different realities as there are people to impose them upon the brute facts of the universe. If reality is formed by a human mind imposing patterns on metaphysically unconnected particles of existence, then every mind can potentially create a new reality.

Everything’s relative. Different strokes for different folks. Clap along if you know what happiness is to you.

In other words, there is no such thing as certainty in our universe. Hume stared into the great deepness of such an hopeless abyss and simply gave up. He quit. His own words are worth quoting:

“Where am I, or what? From what causes do I derive my existence, and to what condition shall I return? … I am confounded with all these questions, and begin to fancy myself in the most deplorable condition imaginable, environed with the deepest darkness, and utterly deprived of the use of every member and faculty.

Most fortunately it happens, that since Reason is incapable of dispelling these clouds, Nature herself suffices to that purpose, and cures me of this philosophical melancholy and delirium, either by relaxing this bent of mind, or by some avocation, and lively impression of my senses, which obliterate all these chimeras. I dine, I play a game of backgammon, I converse, and am merry with my friends. And when, after three or four hours’ amusement, I would return to these speculations, they appear so cold, and strained, and ridiculous, that I cannot find in my heart to enter into them any farther.”


Bertrand Russell was one of the most eloquent philosophers of the twentieth century. Russell, recalling the exhaustion that swept over Hume when he found himself in a dead-end alley, and yet in possession of more vigor to carry on than Hume, said that “we must either accept the inductive principle on the ground of its intrinsic evidence, or forgo all justification of our expectations about the future.”

Russell was clear: the inductive principle must be arbitrarily assumed. The foundation for most of our reasoning, and certainly all of science, is an arbitrary — that is to say, irrational — cornerstone.

But of course, this did not concern Russell. He was not after truth or certainty because he didn’t believe they exist. “Philosophy is to be studied, not for the sake of any definite answers to its questions since no definite answers can, as a rule, be known to be true, but rather for the sake of the questions themselves.”

In fact, it was the opposite of certainty that Russell hoped to achieve in this life: one of the crucial reasons to study philosophy is to “enrich our intellectual imagination and diminish the dogmatic assurance which closes the mind against speculation.”

He abhorred assurance because assurance implies certainty, and certainty implies truth, and truth implies God: “Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me” (John 14:6).

Hume wasn’t so openly antagonistic against the knowledge of God, but he was rebellious inwardly as revealed by his unsatisfying conclusions and subsequent refusal to explore other avenues — mainly, Christianity — in his pursuit of “truth.” He turned a blind eye. Russell was more self-conscious in his hatred of God, if the title of a collection of essays, not to mention their content, serves as any evidence: Why I Am Not A Christian.

Dr. Bahnsen refuted Russell and pointed out the numerous self-contradictions evident in Russell’s essay in a series of articles you can read for free by clicking here:


4 responses to “Reason alone is incapable of rationally justifying its own existence

  1. Pingback: If logic can’t be used to justify reason, can an appeal to irrationality? | Rebuild Your Biblical Worldview

  2. Thanks for this excellent summary of Hume’s argument! You might enjoy watching this video.

  3. Pingback: If atheism were true, science would be impossible | Rebuild Your Biblical Worldview

  4. Pingback: False dichotomy: faith vs. fact | Rebuild Your Biblical Worldview

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