A quick survey of literature:

Goel V. Anatomy of deductive reasoning. Trends Cogn Sci. 2007 Oct


García-Madruga JA, Gutiérrez F, Carriedo N, Moreno S, Johnson-Laird PN. Mental models in deductive reasoning. Span J Psychol. 2002 Nov

Prado J, Chadha A, Booth JR. The brain network for deductive reasoning: A quantitative meta-analysis of 28 neuroimaging studies. J Cogn Neurosci. 2011 Nov

tells us:

1. Neuroscience uses a lot of imprecise terms: "involved in", "related to", "region", "assumed".

2. Logical processing occurs, not in a single brain structure, but through various combinations of disparate brain regions.

Accepted that 1. indicates that it is early days, and Science may yet answer my questions. However, I think, such inductive processes will not easily get to deductive certainty. And from 2. we see that our brains do not handle logic in the same (material) way as a computer.

In our species' pre-semantic past we could not learn by deduction, we had to acquire language in order to start teaching each other... also see related:

Based on evolution, do we arrive at deductive principles inductively?

Implications of a discovered mathematics

Similarly infants learn by induction until they have learned enough to benefit from deductive learning {or they become teenagers}

Now Either: We are born with a capacity for Deduction; but with no innate brain structure to support it: Where does it come from?

Or: We gain access by non-deductive means (emergence maybe?). Does this constructivist approach entail that we brought Deduction into the Universe?

Is there literature on the metaphysical origin of deductive forms? Or any references on multiple intersecting Ontologies?

  • I realize deductive reasoning and learning is not equivalent. But the structures or objects of it are still the same. – christo183 Jun 21 '18 at 13:49
  • 1
    Sorry, I do not follow what the question is or how it is different from the linked one. Deductive reasoning is certainly a human creation, so we did "bring deduction into the universe". Presumably, there are biological predispositions to it that evolved because they conferred some adaptive advantages on our ancestors. In this sense at least they are not "alien to the material world". I do not see why acquiring more advanced deductive skills is any different from acquiring any other skills and would require "emergence", and there is no "deductive certainty" when it comes to empirical matters – Conifold Jun 21 '18 at 18:36
  • The linked question is about an apparent logical dilemma, this is about the possible ontological implications. If we created deduction then there was a time when only inductive skills existed, where then would "biological predispositions" come from? I'm contending that in a world where only induction were extant, "deductive certainty" is essentially alien. So does that imply that Ontology must include some kind of formal sphere distinct from the material? – christo183 Jun 22 '18 at 3:51
  • @Conifold, it's not really human creation like hand is not. It is a result of evolution (as you say) and people evolved to reason deductively (sometimes). I think animals also have some kind of deductive reasoning: this is food, if I will eat it, I will get satiety. – rus9384 Jun 22 '18 at 6:09
  • I'd suggest adding "Gödel, Escher, Bach" by Douglas Hofstadter to your book list (it's a very long book) in order to see a view on the matter that might help you. Generally, it isn't necessarily true that the brain and the computer works the way you suggest. Alternatively, a different view might suggest that those "inductions" comes form an a priori deductive reasoning that allows those inductions. – Yechiam Weiss Jun 22 '18 at 6:54

The phenomenon of consciousness have long been a vexation to philosophers. Explanations have over the millennia been informed by the vogue of contemporary thinking. Most recently under the influence of Scientism and Materialism we are availed of some of the most in depth and comprehensive expositions to date. In the, required reading, texts

Gödel, Escher, Bach: An Eternal Golden Braid and I am a Strange Loop - Douglas Hofstadter

recants how recursion and emergence gives rise to Consciousness, overall a conceptual treatment.

The Remembered Present - Gerald M. Edelman

Is a proper scientific theory touching on areas such as evolution and Neural Darwinism. This is a biological description of how consciousness happens. And finally

Shadows of the Mind: A Search for the Missing Science of Consciousness - Roger Penrose

which blames it all on Quantum action.

So why all the Consciousness talk, when the topic is Deduction

Since the days of Plato there is a recognition that certain Formalisms appear to be innate: 1+1=2 is True regardless of the symbols "1" and "2" and we assign "+" to an operation that can be mechanically expressed. Similarly with Logic we find such structures that can be recognized in physical actions (infra high order processing): If I touch a hot stone, it will hurt; this stone appears to be hot, therefore I will not touch it. Indeed according Johann Gottlieb Fichte gaining awareness of something cannot happen without an immanent fraction of prior knowledge. Awareness is possible because the necessary mechanisms is already present. Furthermore it is hard to imagine how Immanuel Kant's a priori knowledge could be developed sans a conscious mind. The declarative nature of such knowledge, whether immanent or from intuition, requires that once a fact has coalesced it be repeated by the mind in a suitable language.

It can be seen that our awareness of Deductive Logic is fundamentally facilitated through the contrivance of the conscious mind.

Thus we have to distinguish Reason as 1) the object and method of self discourse and Reason as 2) the innate structures and relations that is the subject of that discourse. This is no easy task precisely because it is our very apparatus of scrutiny, under scrutiny. See:


But for all that we can see that there are in nature, apart from human activity, expressions of Deduction, we can deduce that Reason preceded us. The ultimate ontological status of Deductive Reasoning, however stays elusive.

Note the idea of placing objects in different ontologies and examining the intersections, is meant to be analytically propitious.


First: It is not clear to me that our brains could not have an innate ability to do deductive reasoning from the moment we're born: like you say: it's early days in neuroscience, and the imprecise terms you mention may be more of a reflection of either just not knowing enough detail about how the brain functions, or of the fact that these imprecisions are 'located' at a different level than the 'deductive logical reasoning level'. What I mean by the latter is: if you go deep enough into the physics of a computer, we'll find imprecisions in the functioning there as well, but for all practical intents and purposes, at a 'higher', more s\abstract level of abstraction, the working of a computer is all exact

That said, if I had to guess, I would guess that the brain does in fact not have the innate capacity for deductive reasoning ... but that humans do have that innate capacity, and that we learn to in fact do this. What I mean is that when we reason, we use more than just our brain: we also use specific systems of symbols (logic! math!), and using those symbol systems, we can reason deductively. The role of the brain is 'merely' to 'manage' the symbol manipulations, but in combination with those symbol systems, deductive reasoning is taking place. So, deductive reasoning was introduced as symbol systems were introduced ... and please note that I am not saying that we didn't reason deductively before we got those mathematical and formal logic symbol systems: through natural language we can of course set up deductive arguments as well: we just need some representational system that the brain can interact with and we're off and running.

  • The circuitry in a computer chip can be directly mapped to a formal logical language. Brains don't have that. – christo183 Jun 22 '18 at 4:05
  • I like how you envision the use of symbols. But that begs the question: What are the objects the symbols stand for? And where do they come from (ontologically)? – christo183 Jun 22 '18 at 4:15

Bram28 clearly exhibits an 'intuitional' grasp of the origin and nature of deductive reasoning. Once again it is Spinoza who clarifies the difference between deductive and inductive reasoning and selected the former as the only one to deliver certainty and truth. He explained that the subject matter of inductive reason, what he termed 'modalities' or what we term the sensible world, even as Hume understood it, can never deliver certainty because of two features: 1- The entire sensible world, including 'Higgs Boson' are contingencies; they include in their make-up no causality and any study of them will never deliver the 'truth of reality' since they contain no aspect of necessity or self-causation, and 2- The sensible world includes an infinity of objects so that the common practice in theoretical science of chasing after smaller and smaller entities in the hope of discovering a 'universal source element' is fruitless. Spinoza espoused on the contrary to begin at the highest macro-level possible, the entire system which 'created' the universe and to 'deduce' all other principles from that point. I suggest reading "The Foundation of Metaphysics in Science" by Professor Errol E. Harris, to flesh out this hypothesis. Sapere Aude, CS

  • Would you have references to Spinoza and quotes from him to illustrate his position on the two points you have listed? This would strengthen your answer and give the reader a place to go for more information. It also may be helpful to the reader to format this into multiple paragraphs. Welcome! – Frank Hubeny Mar 26 at 16:34
  • Thanks Frank, The first point is essentially taken from one of my works, Letters to No One in Particular- A Discussion and Illustration of Spinoza's 'Fragment'-The second point is from the 'Fragment' better known as the TIE, Tractatus Emendatione Intellectus. It's only 43 pages long but is where Baruch exhorts us to begin our investigation with 'the most perfect being, Deus sive Natura'. – Charles M Saunders Mar 26 at 18:43

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