The whole premise of Hume’s An Enquiry Concerning Human Understanding was to delineate the limits of human understanding and put a rest to metaphysical speculation by grounding philosophical reasoning in experience rather than pure reason. From the outset Hume’s preferred method of inquiry is scientific, based on observation and experimentation, rather than purely abstract reasoning. He posits that any fruitful beliefs about the world must be rooted in experience rather than wholly reflective theorizing.
I will begin by briefly summarizing Hume’s primary claims regarding his empiricism, skepticism, and naturalism and illustrate his emphasis on each of these in an effort to show that his philosophy is consistent and equally supports all three. I will ultimately conclude that his account of naturalism is the least developed of the three. This paper will then examine the methods and their accuracy that he employs in developing each of these.
Hume begins in Section I by providing a framework of two types of philosophical thinking which he calls the “easy and obvious” philosophy and “accurate and abstract” philosophy. He characterizes the “easy and obvious” philosophy as pertaining to moral reasoning dealing with applied action and practical matters related to every day life. It is an ethical enterprise relying on sentiments, vice and virtue, appealing to the commonsense of daily life and right and good living. In contrast, the accurate and abstract philosophy is rooted in abstract reasoning and reflection where particular instances are generalized through inference. The problem that Hume saw with accurate and abstract thinking was that it is conclusions could rarely be applied to practical every day matters. The upside that Hume saw was that accurate and abstract thinking honed the ability to reason accurately when applied to practical matters.
After establishing this framework between the “easy and obvious” philosophy and “accurate and abstract” philosophy, Hume establishes another dichotomy in Section IV between “matters of fact” and “relations of ideas”. By “matters of fact” Hume refers to the a posteriori knowledge induced by experience at a given time through the impressions made by the sensible qualities of bodies. These sensible qualities are ascertained by abstract reasoning as we identify a bodies color, extension, solidity, and the like. Hume contends that matters of fact are neither true nor false, but only probable since no proposition regarding a matter of fact can produce a contradiction since a negation of a fact may always exist. “Relations of ideas” are those analytical propositions that are necessarily true by definition, such as those found in geometry and algebra. These propositions can be said to be demonstrably true or false based on a contradiction of the truths of necessary definitions.
Hume says that while the mind is capable of producing inferences, it is impossible to reason the cause and effect of matters of fact without experience. Any effect we observe is bound to a cause that is only discoverable through observation. Hume shows that, despite the efforts of great thinkers throughout history, no one has been able to discover a secret power or ultimate cause within substance that shows a necessary connexion between its cause and effect. The corollary of his reasoning is that, since we cannot reason about the effects of matters of fact without experiencing their causes, any metaphysical speculation cannot be rationally justified and pursued. Instead, Hume says the appearance of cause and effect is the result of the mind conjoining associated phenomena, so that cause and effect is more correlative of similar outward impressions based on custom and habit rather than the result of some inward necessary connexion. However, the custom and habit that we rely on to reason the cause and effect of matters of fact utilizes an inductive method which must suppose a principle where the past resembles the future. Because all matters of fact are subject to the possibility of change, and since there can be no necessary cause for any effect to be certain of, the inductive method yields knowledge claims in terms of probability rather than the certainty of true and false.
In developing his empiricism Hume is primarily concerned with showing that reason alone is insufficient for determining knowledge claims about the world. According to him, all reasoning of cause and effect is a result of the principles of connexion, which conjoin the associated phenomena of bodies by similar resemblance, contiguity and causation, rather some inherent secret power that produces necessary connection. His main contention is that the limits of human understanding about the natural world are constrained by experience, that our knowledge about “matters of fact” is dependent and bound by perceived sensations. Reason that infers matters of fact without experience of their causes leads to obscure and unworkable conclusions. He argues that a priori assumptions of pure reason are superfluous and arbitrary since there is nothing within nature that makes them and their inferences necessarily true. The primary aim of fruitful inquiry, then, is to root matters of fact in experience through a scientific method of experimentation and observation in order to produce a consistency which may yield principles and laws.
Throughout the Enquiry Hume applied a skeptical approach that differed from his predecessors. Instead of characterizing his type of inquiry as skeptical, he preferred to see himself as being philosophically curious, so as to not to fully overextend merit of skeptical thinking. This characterization reflects his motives throughout the Enquiry as being primarily pragmatic and concerned with keeping his philosophy relevant and applicable. As such, Hume utilized skepticism as a means of uncovering the limits of human reasoning by doubting how it is we arrive at knowledge. He understood the merits of skeptical doubt, but also saw its shortfalls. His aim was to progress understanding and knowledge without giving too much weight to man’s ability to form conclusions based on reason alone.
In Section XII Hume identified two kinds of skepticism, namely antecedent and consequent skepticism, and further distinguishes as each possessing a moderate and extreme form. The skepticism demonstrated by Descartes, which Hume calls extreme antecedent skepticism, subjects all sensations and judgments to universal doubt in order to first derive some a priori, foundational principles. The corollary of this skepticism, according to Hume, is that there is no first principle which is inescapable from doubt. He further contends that, even in the event that a principle was discovered, any conclusions that follow would not be immune to doubt. Furthermore, this extreme form leaves the mind with no firm conviction or direction on any subject. An inherent problem with antecedent skepticism is its use of reason to establish existence, as demonstrated by Descartes I think, therefore I am. This fails Hume’s standards because reason alone can not make existence claims by instantiating “matters of fact” through inference. Matters of fact are derived through by experience alone. Hume praises the moderate form of this antecedent skepticism which seeks to establish first principles by progressing incrementally. This moderate form continually calls into question the employed methods of reasoning by uncovering prejudices and shedding biases and inaccurate opinions in order to preserve impartiality.
Throughout the Enquiry Hume employs consequent skepticism to question customary conclusions and judgments and the ways in which they are ascertained. He argues that perceptions are the primary guide to experiencing an external world and that it is through our perceptions, which by natural instinct yield forceful and lively impressions of the sensible qualities of objects, that we suppose an external reality independent of the mind. In this way we justify our belief in an external world through experience. The problem with this reasoning is that, though we assume the reliability of the perceptions to render accurate representations, perceptions are prone to change with experience and subject to error. Hume claims that, while experience provides justification for belief in an external world, experience alone cannot allow us to transcend perceptions. This leads Hume to conclude that belief in an external world is ultimately irrational and unjustified.
Hume shows that utilizing the extreme form of consequent skepticism leads one to doubt the reliability of our senses to such a degree that one could not conceive the extensional and solidity qualities composing a body. In addition one would not be able to conceive causation since all rationally justified conclusions depend on observation. If this were the case we could not form any judgments about matter whatsoever and ultimately lead to complete inaction. While useful in excessive theorizing, this Pyrrhonist skepticism produces no fruitful conclusions for useful action and right thought. The natural instincts of man, and even of animals as Hume points out, do not allow us to apply this skeptical reasoning, and any doubts we may have are quickly amended as a matter of practicality and commonsense. As a result, Hume prefers a moderate consequent skepticism, or mitigated skepticism, which seeks to recognize and balance dogmatic and obstinate beliefs by subjecting them to counterpoising arguments and contrary methods. This moderate form allows for proper moral reasoning that recognizes the limitation of certain enquiries and appreciates the narrow capacity of human understanding. In this way Hume balances his task of developing an easy and obvious philosophy that is both accurate and exact by utilizing doubt to clarify and revise methods of belief for accuracy and exactness.
Because Hume placed so much emphasis on experience to render knowledge and doubt to make ensure impartial accuracy, he left little room for a fully developed account of his naturalism. Unobserved phenomena held little merit for Hume and speculations that could not be readily tested were pushed aside. His philosophy fully appreciates the reality that perceptions are inexact and fallible representations of external bodies, at best, that will never admit a definite and satisfactory accuracy about their nature and existence. As such, Hume doesn’t make absolute instantiations about the existence and nature of a material world outside what can be perceived. For Hume all we can do is subject our senses to experience and continually revise the way we organize how these senses are perceived by calling conventional methods and habits into scrutiny.
Hume’s empiricism and skepticism seem to be weightier and better supported when compared to his naturalism. His undertaking to devise a new philosophy grounded in experience was a matter of practicality. He wanted to put an end to what he considered fruitless metaphysical speculation that lead to obscurity. His philosophy emphasized the role of the cognition that is incapable of discovering anything about the necessity of nature. Nature does not exist without a mind to perceive it, and any speculation is an empty attempt to get at its objective independent truth. Laws and principles, he said, were a matter of habituation and custom alone, the conditioned expectations of cause and effect gained only after experience. For Hume, cause and effect is a matter of the mind associating two perceived phenomenon occurring in conjunction that lead us to believe in a necessary relationship. As a result, the mind’s ability to reason and ascertain natural knowledge is bound by experience rendered from habits of perception.
Hume is realistic in how he characterizes the limits of human understanding. He sees that while skepticism is a useful tool, it has limits. Since he is concerned with developing an easy and obvious philosophy that is accurate and exact, he concedes that, while it is impossible to know absolutely for certain that an external world exists independent of our perceptions, such a philosophy is untenable for progressing human understanding. Using a moderate consequent skepticism, he outlines what we can know realistically, namely matters of fact and their causes derived from experience, and delineates the limits of our methods for ascertaining these matters of fact, namely our ability to perceive the impressions which appear to our cognition. Since experience renders all matters of fact, Hume shows that the impetus for developing understanding is activity, whereby action quells doubt through applied observation and experimentation. Hume sees that the accurate and abstract philosophy is beneficial for refining inquiry and producing doubts by reflective scrutiny.
Hume’s views are thoroughly consistent and coherent through the Enquiry. In his formulation he allows for a philosophy that is unhampered with endless skeptical speculation common throughout metaphysical inquiry. His emphasis on naturalism and experience as the starting point for understanding and knowledge, and his dubiousness in our ability to accurately render relationships such as cause and effect within our experience, creates a very practical philosophy that is tenable even by today’s standards.