There is always circularity involved when considering logic, reason and rationality. One set of definitions gives:
- Logic: The study of valid reasoning.
- Reason: A broader concept that encompasses logical thinking, critical thinking, and problem-solving.
- Rationality: The quality of being reasonable or logical.
What is logical is not always considered reasonable. Yet we derive the rules of our logic from our reason. If we try and define what reason is we come back to logic and what is rational. But we also differentiate between logic and reason and rationality. It seems to me that all claims of objectivity whether for logic or reason or rationality are trying to square the circle.
Thinking through the nature of logic and its relationship to human reason, I am struck by the idea that logic, as we know it, may be much more of a human construct than being anything objective or universal. Logic, with its clear-cut rules of deduction, can only be a mirror of the world we claim to observe. It is a reflection of how humans perceive the world—through patterns, cause and effect, and binary distinctions between truth and falsehood. The concept of truth and falsehood as binary and mutually exclusive is a foundational assumption in classical logic, and propositions are either true or false without any middle ground. (The Law of the Excluded Middle). The rules of logic derived by reason are assertions and are fundamental assumptions. The binary distinction between true and false and that the one excludes the other is also just an assumption. It does not reflect all that we observe. It seems logical to us to say that if A is true, then B must follow, and if not-A, then not-B. But is this framework truly a reflection of the world as it is, or just a convenient tool we’ve developed to make sense of our observations?
I conclude that logic is inherently tied to the human mind – and particularly to individual human minds. It is a product of how we, as humans, experience the world through our senses, our language, and our understanding of cause and effect. Our observations, no matter how often repeated, and no matter how many times duplicated, are all perceptions. A delusion shared by multitudes does not make it true. A perception shared by billions does not make it any more objective than a single individual’s perception. The idea of something being “true” or “false” may not be a feature of the universe itself but a structure imposed by human cognition. A spider, for instance, will perceive the world in ways that are entirely alien to us, and it may have an entirely different logic that makes sense within its own experience. What we call “logic” could thus be nothing more than a human artefact, and there might be other forms of reasoning—unknown to us—practiced by other species or even extraterrestrial beings.
I must reject the idea of an absolute, objective logic. If logic is shaped by the mind that perceives the world, it cannot be universal. It must always involve the observer, making it inherently subjective. What we consider logical may not be logical to other beings whose cognitive processes are different from ours. I am quite certain that our pets do not consider our actions always to be logical. Logic, as a formal system, can only tell us what conclusions follow from given premises according to certain rules, but it does not tell us why those rules reflect the reality we observe—or whether they would hold in different contexts or for different minds. The rules of logic only give us an assumed correct process of thought, given a starting true condition, to reach other true conclusions. But logic does not attempt to define what truth is. It takes as a foundational assumption that what is not true is false and vice versa.
Hence, logic clearly is connected to but is not the same as reason. Further, I find it interesting to explore the distinction between what is reasonable and what is logical. There is no law of nature which requires us to act logically (or reasonably for that matter). Human actions may overrule what is logical to instead be reasonable or even unreasonable. While logic is about formal consistency, reasonableness is about sound judgment within the real-world context. A conclusion can be reasonable—based on experience, intuition, or practical considerations—without being strictly logical. Conversely, something can be logically valid but still seem unreasonable when we take into account broader factors like emotion, ethics, or practicality.
Thus, human reason is much wider than logic alone. I like to think of it as logic being the correctness part of that part of the thought process which needs to be bound by rules. Reason needs much more than just thinking correctly. Reasoning often involves flexibility, considering context, emotion, and pragmatic outcomes, whereas logic is strict and rule-bound. It is this broader sense of reason that helps us navigate the complexities of human life, and where strict logic fails to account for the richness of our experiences.
I conclude that logic is a guideline for structured thinking, but it is not synonymous with being reasonable. It is a product of human thought, applied to our thinking. It is tied to our perception and cognition, and its validity can only extend to be within the boundaries of what we can observe or understand. Reason, on the other hand, embraces a much wider scope. Reason brings judgement into play. To make judgements needs a set of values to compare with. The use of reason is what brings a judgement of what is “best” to do into play. Logic only allows us to follow the rules but reason allows us to act wisely and sensibly in a world that is often too complex for formal logic to capture.
But it also means that logic applies only to thinking and is no constraint on human actions. Reason is what we often use to overrule logic and as the justification of our actions. In this way, reason functions as the adaptive, real-world application of human thinking, whereas logic remains an internal tool for organizing thoughts, not necessarily dictating how we behave.
Even truth is an artefact of the mind. The world around us exists – it is. That part we perceive as observations (direct or indirect or implied) we take as being existential truth. This is the closest we get to any absolute truth and even that is tainted as being a perception of a human mind with all the limitations and foibles of that mind. A brute fact it seems, but still subjective. And everything else we take as truth is just a perception in a human mind.
Logic, reason and rationality are all artefacts of human minds. They are all subjective. There is no such thing as objective logic – except as a subjective perception.
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