Hume’s Enquiry Concerning Human Understanding

After an introduction that discusses different approaches to doing philosophy–the easy and obvious approach taken by essays designed to affect people’s conduct (i.e., through appealing to their emotions and inciting their passions) and the accurate and abstruse approach that we must take when we are concerned to test, correct, and deepen our understanding–Hume focuses on what he calls ‘perceptions of the mind’.

These perceptions are divided into two kinds: Ideas and Impressions

Distinction between Ideas and Impressions

The characteristic by which we distinguish between Ideas and Impressions is their relative degree of force and vivacity

  • Less forcible and lively perceptions are thoughts or ideas.
  • More forcible and lively perceptions are impressions:

The other species want a name in our language and in most others, I suppose, because it was not requisite for any but philosophical purposes to rank them under a general term or appellation. Let us, therefore, use a little freedom and call them impressions, employing that word in a sense somewhat different from the usual.

By the term impression, then, I mean all our more lively perceptions when we hear, or see, or feel, or love, or hate, or desire, or will.

And impressions are distinguished from ideas, which are the less lively perceptions of which we are conscious when we reflect on any of those sensations or movements above mentioned. (A & W. p. 539, left column)

Relationship between Ideas and Impressions

Ideas are copies of impressions

Hume provides two arguments that are intended to establish this claim:

First argument:

Part I: analysis of ideas; analyze complex ideas, then find they resolves themselves into simple ideas; these simple ideas are copied from some prior feeling or sentiment. (God = infinitely intelligent, wise, and good being; reflect on our own mind and augment, without limit, the qualities of goodness and wisdom)

Part II: If you want to deny the UNIVERSALITY of the conclusion, produce a counter-example (an idea that is not derived from this source)—we will defend the view by producing the impression which corresponds to it.

Second argument:

Part I: A person who lacks one of the senses, won’t have any of the corresponding ideas (blind people don’t have ideas of colors, deaf people don’t have ideas of sounds).

Part II: Respond to possible counter-example—form an idea of x through comparison of impressions of things resembling x; have the idea of x, but it is not copied from an impression of x. Dismiss the counter-example and claim it does not force us to alter our GENERAL maxim.

With these claims on board, Hume then articulates a maxim or a principle for philosophical investigations like those he will carry out in the Enquiry.

When we entertain, therefore, any suspicion that a philosophical term is employed without any meaning or idea (as is but too frequent), we need but inquire, From what impression is that supposed idea derived? And if it is impossible to assign any, this will serve to confirm our suspicion. By bringing ideas into so clear a light, we may reasonably hope to remove all dispute which may arise concerning their nature and reality. (A & W, pp. 540-41)

The next thing Hume brings to our attention is the fact that ideas in the mind are connected in somewhat regular ways. They do not simply exist as individual ideas, but they also exists as members of chains of connected ideas that lead our thinking from one idea to another in predicatble and methodical ways. This association of ideas is something that Hume is interested in investigating: what are the particular ways in which ideas are associated with one another, and how do they get associated with one another in these particular ways?

Hume identifies three principles of association of ideas:

1. Resemblance (a picture leads to the idea of the original)
2. Contiguity (the idea of a part leads to the idea of other parts)
3. Cause or effect (the idea of bodily harm leads to the idea of pain)

It is this last kind of association that will be the main point of focus in Hume’s investigations into the human understanding, since it is the one that we make use of in reasoning to conclusions about the existence and characteristics of things and events that we do not immediately perceive.

General View of the Understanding

Humes general view of the understanding is outlined in the the two part section where he presents skeptical doubts concerning its use and a skeptical resolution of these doubts. The basic theses involved are:

  1. All reasoning about Matters of Fact is based on the relation of Cause and Effect
  2. Particular Knowledge of Cause and Effect is not arrived at through Reason but through Experience
  3. The fundamental basis for Inferences from Experience is not Reason, but Custom or Habit.

In other words, reasoning about what we do not directly experience is a process that is based on a general understanding of things that we have gained through experience. Experience teaches us about ‘how the world is set up’ and, once we have learned that sufficiently, we can use our understanding of the general order of things to ‘fill in the gaps’ left open by our immediate perception.  Experience provides the associations between ideas that we make use of when we follow out our chains of thinking and arrive at some conclusion about existing things.

If we think carefully about this mode of operation, however, we should realize that it rests on a rather significant presupposition; namely, the presupposition that the future will resemble the past, or, more generally, the presuppostion that what we do not experience is like what we do experience in ways that are sufficient for us to rely on the information provided by experience in drawing conclusions about things that are beyond our experience:

  • Under the presupposition that i) tomorrow will be relevantly similar to yesterday and all the days I have experienced prior to then, and ii) the sun has risen on each of these days: it is reasonable for me to conclude that the sun will rise tomorrow
  • Under the presupposition that i) the next swan I observe in nature will be relevantly similar to the other swans I have observed previously, and ii) the others I have observed have all been white: it is reasonable for me to conclude that the next swan I observe will be white

So, in addition to presupposing certain features of my previous experience (i.e., the sun always rising, swans always being white), I also have to presuppose a general principle about the similarities between known instances and (as yet) unknown instances:

This is a principle that I cannot possibly know through experience, since all my experience deals with known instances. I don’t have the access to unknown instances that would be necessary to establish that they are similar enough to known instances for me to make use of what I have learned from experience to reason correctly to conclusions about them.

This is a principle that I cannot possibly know a priori, since all a priori reasoning, according to Hume, concerns relations of ideas. The principle I am appealing to is a claim concerning a matter of fact (i.e., either the unknowns do, in fact, resemble the knowns or they do not, in fact, resemble the knowns).

I cannot directly perceive the truth of this general principle, and I cannot reason about it a priori, so the only way to decide the principle is true, and thus reliable, would be to reason about it on the basis of experience… but, what is the general principle we make use of every time we reason on the basis of experience? Oh, yeah, it is the very principle that is in question here…

This presents a problem for us, in Hume’s view, only if we insist that prior certainty concerning the truth of the principle is required for us to trust our use of it. That is, if we accept the Cartesian view that we should not trust our faculties unless we have independent verification of their reliability in leading us to truth, we might conclude that we cannot trust our reasoning about matters of fact at all. The more natural response, however, would be to conclude that we cannot trust our faculties completely, so we cannot trust the results of our reasoning about matters of fact completely, but that does not mean that all trust in them is misguided. We trust our understanding, not because we have independent verififcation of its reliability, but because it is all that we have to appeal to in circumstances like these.

Recognizing that our use of the understanding in reasoning about matters of fact is ultimately grounded in customory or habitual beliefs about the regularity of nature (that are themselves products of that regularity), rather than in rational insight concerning the necessary order of nature, is, for Hume, a way of humbling our pretensions and reminding ourselves that there are natural limits to the exercise of our capacities.


More Details about this General View

  • Reasoning about Relations of Ideas and Matters of Fact

Relations of Ideas = Cartesian Immutable Natures (logically necessary truths)

  • Claims in Geometry, Algebra, Arithmetic
  • Intuitively Certain (triangles have three angles and three sides–denial is a direct contradiction)
  • Demonstrably Certain (square of the hypotenuse is equal to the square of the two sides–follows from a chain of logical inferences that makes it such that denying the conclusion creates a contradiction with some step of the proof)
  • Discoverable by thought alone; i.e., without reference to any existing thing

Matters of Fact = Claims about Existing Things (logically contingent truths)

  • Claims in Astronomy, Physics, History
  • Not intuitively Certain (the sun will rise tomorrow–denying this claim may lead me to say something that is, in fact, false, but it doesn’t lead me to say something that is logically inconsistent. The truth or falsity of the claim depends on matters of fact concerning the sun and the earth and the future)

If we are going to treat it as being demonstrably certain, we can’t just start with things that are intuitively certain (e,g, spheres have these qualities, elliptical paths are described by this function, etc.) All of these mathematical truths hold independently of any existing things, so they can’t justify claims like ‘the earth spins on its axis while it traces an elliptical path around the sun’–these are all claims about matters of fact–not relations of ideas.
So, if we are going to have any kind of certainty concerning claims like this one, we have to discover another source for it.
We have sense experience and memory as sources of intuitive certainty concerning matters of fact. But, the claims of Astronomy, Physics, and History take us a long way away from our own sense experience and our own memories.
What is the evidence that assures of any matter of fact that we have not directly been witness to?

  • All reasoning about Matters of Fact is based on the relation of Cause and Effect

Intuitive knowledge about matters of fact is based on direct experience and memory.
All other knowledge about matters of fact is based on reasoning from matters of fact that we take to provide evidence for other matters of fact
A letter postmarked from Paris is taken as evidence that our friend is in Paris (though we are not there to see her, and to establish that on our own)
A watch on the beach is taken as evidence that some humans have been there before us (though we were not there to see them)
Hearing sounds that we can make sense of as linguistic expressions is taken as evidence for the presence of someone who is talking (though we don’t currently see that person)

Whenever we assent to the truth of claims about matters of fact that we do not directly experience, we do this on the basis of evidence following the formula:
y exists, and must have some cause x, which therefore also must exist and have the capacity to produce y.
(Sound familiar? Descartes? I exist with the idea of God, and must have some cause, who exists and is capable of producing me with this idea)
But, where do we get the knowledge of what particular things cause what particular other things that we have to have in order to plug in particular values for y and x here?
Why don’t I:
See a letter postmarked from Paris and take it as evidence that my dog is a terrier
See a watch on the beach and take it as evidence that watches grow in the sand around here
Hear sounds that I take to be linguistic expressions and conclude that tomorrow is Tuesday

  • Particular Knowledge of Cause and Effect is not arrived at through Reason but through Experience

Our knowledge of what particular things in nature cause other particular things in nature is a product of our experience with particular things in nature.
We can’t simply take some natural object, look at it carefully, and deduce a whole bunch of things about what effects it has.
We come to an understanding of how to connect particular causes and particular effects through repeated experience with things of similar kinds–the effect of the motion and impact of billiard balls is not something I can anticipate purely through reason–it is something that I know about through having played billiards and noting what happens when one ball impacts another.
I don’t know that people make watches just by knowing what a person is and deducing it from there. I have experience that leads me to understand what watches are and that and how they are made by people.

  • The fundamental basis for Inferences from Experience is not Reason, but Custom or Habit.

Inferences from experience rely on accepting a fundamental principle concerning the relation between past experience and future experience:
In my experience x’s have always caused y’s

Therefore, x’s will continue to cause y’s
(The future will resemble the past).
Okay, so let’s say this is actually what we assume whenever we are reasoning about matters of fact.
How do we justify this assumption?
Can we demonstrate that it is true?

Hume’s Skeptical Naturalism Concerning the Understanding

Internalism vs. Externalism in Explanation and Justification for Belief

Cartesian Internalism: There are intrinsic features of ideas that explain our assent to their truth, or our belief (i.e., clarity and distinctness); We are naturally prone to assent when certain C & D conditions are met, but we can also ask about the status of our natural habit to assent under these conditions. Does the explanation also provide a justification (i.e., can it go beyond telling us why we believe, or how we come to believe, and allow us to show that it is also what we ought to believe; e.g., because its true or because it is useful). Maybe we have been set up with unreliable gear–we can’t help but to believe when these conditions are met; yet, we have no guarantee that these beliefs track reality or that it really does pay to follow them (this is the hyperbolic or metaphysical doubt that Descartes entertains with respect to mathematics through invoking the idea of an evil genius).

For an internalist about justification, there is an objectively satisfactory solution to this worry; i.e., one that takes the form of a rational justification for our habits of believing. We come to grasp through the intellect that our capacities are, in fact, reliable and that we can be sure to get it right, when we exercise our will appropriately (Descartes finds this guarantee in the conviction that there is a perfect God who sets us up to be able to discover truth and who would not deceive us). When we abstain from assenting intellectually, and we keep considering the matter to be theoretically unresolved as long as our ideas remain obscure and confused, we can avoid error. This doesn’t mean we suspend all practices that are shaped by our belief–e.g., our habits of doing things like jerking our hand away when we feel intense pain, eating bread when we feel hungry, drinking when we feel thirsty, etc. It just means that we do these things with a different attitude towards our beliefs and our behaviors than we have, e.g., when we solve problems in algebra, or give geometrical proofs.

Concern with Cartesian View for Physics:
A common concern about this model of justification is that it seems to be much more compelling when it comes to dealing with logic and mathematics than it does when it comes to dealing with knowledge of the natural world. We rarely, if ever, have ideas of naturally existing things that don’t require us to suspend judgment in many ways, if we want to avoid error, and that don’t involve us in considering probabilities and sorting through a mess of particulars that we are looking to order and relate to one another.

The bodies we find in nature do resemble geometrically described figures in some ways, but it is a long way from there to treating physics as nearly identical with geometry–the more pure geometry involved in our models of nature, the greater clarity and distinctness will be involved, and the more we might like to think that the great book of nature is written in the language of mathematics. The more we look at the book itself, and the more we reflect on our capacities to read everything that is written in it, however, the further we get from the kind of questions where geometry proves to be most helpful.

One of the biggest differences between Newtonians and Cartesians is that Newton and his followers don’t treat bodies as being merely extended and causally inert–in addition to bodies extended in three dimensions, Newton includes fundamental attractive and repulsive forces that explain the causal powers of bodies; the overall systematic effects of the exercise of these natural powers are what Newton is concerned to formulate mathematically with his laws of motion. For Newton, we know about these forces through their effects, but we don’t have any further insight into their operation–we can explicate the machinery through which the cause achieves it effect (e.g., when we have a system of pulleys that allows us to overcome more easily the effects of the attraction between the piano we are moving and the earth) but that is where our explanations cease.

Locke tries to provide a justification for appeals to forces in Newtonian physics by way of a somewhat Cartesian view of mind. Like Descartes, he thinks we have an immediate awareness of our mental powers that gives us a unique perspective into substance, causality, and power in general. From there we can construct views of the essential powers of bodies through relying on these impressions of the mind, and thinking about what it is in a body that explains its capacity to affect my sensory state according to an analog with our own mental powers.

Hume is skeptical about this supposed power of introspection through which we know the self as a substance that acts through some kind of intellectual powers in causing certain effects.

Humean Externalism: There are intrinsic features of our perceptions that explain our assent to them (i.e., force and vivacity). We are naturally prone to assent when certain F & V conditions are present, but we can also ask about the status of our natural habit to assent under these conditions. Does the explanation also provide a justification (i.e., can it go beyond telling us why we believe, or how we come to believe, and allow us to show that it is also what we ought to believe; e.g., because its true or because it is useful). Maybe we have been set up with unreliable gear–we can’t help but to believe when these conditions are met; yet, we have no guarantee that these beliefs track reality or that it really does pay to follow them.

For an externalist about justification here, there are no internal grounds upon which we can confirm that beliefs explained by natural processes really do track reality in a way that would provide a general justification for their acceptance. The intellect cannot guarantee that our belief system in general is truth-reliable; the intellect conceives things from the standpoint of possibility (relations between ideas) not from the standpoint of existence (matters of fact); we can conceive of beings who always (or generally) get it right when they rely on their habits, properly refined, for forming beliefs in natural philosophy, but we cannot know for certain that we are these beings. That is an empirical question we cannot answer through the intellect alone.

If we are going to justify our habits of empirical belief formation, or justify our trust in the senses and reflection for delivering us with knowledge, we need to appeal to experience. We have an acceptable description of belief by way of the force and vivacity of impressions, but we need an account of 1) how we make use of impressions in coming to have beliefs in the case of ideas and of 2) whether or not we are justified in forming our beliefs in these ways.

The justification for an idea, on this view, is provided in terms of an explanatory relationship between the idea and some impression or set of impressions that provides its material content. (It is not provided by reference to some intrinsic feature of the idea… ideas are never forceful and vivid enough to bring our assent to them on their own.).

Any idea that is introduced into a discourse without an account of this explanatory relationship is suspect–no matter how clearly we seek to define an idea or concept, we have no guarantee concerning its use in describing and explaining matters of fact, unless we can connect it to some empirical conditions.

So, experience provides both the source of our impressions and the touchstone or proving ground for our use of ideas, specifically in making claims about the existence and properties of things other than these impressions; i.e., for claims that do not simply report the contents of our mental states, but say something true or false about things other than these states.
What experience can do is provide a way of letting us see whether or not these claims about things are well-grounded. Do the conclusions we reach through our reasoning even make sense? Are we actually asserting something that could be true (or false)? We don’t know that if we cannot specify any impression or impressions that lead us to accept the terms in which the claims are offered.

What experience cannot do is provide any guarantee that claims that are well-grounded in experience and reflection are also TRUE; repeated experience can reveal that we do not have any good reason to reject these beliefs (at least not yet), but we never get any complete and systematic inventory of our beliefs and we never have any independent way of verifying a match between our beliefs about some class of existing things and the things-in-themselves whose properties determine whether or not the beliefs we have formed about them are TRUE.

From the General View to Questions about Particular Ideas 

Example of a Scenario in which experience can play an important role for our reasoning:

P: Do flibbits live in trees?

R: Well, I don’t know. What is a flibbit?

P: Oh, it’s a cross between an owl and a frog.

R: Uh huh, well, owls live in trees, so maybe flibbits do as well. But, then again, some frogs don’t live in trees, so maybe flibbits don’t. SInce almost all owls do, and at least some frogs do, I’m going to say that it is likely that flibbits do live in trees.

We can define our terms in any way we want, but the definition alone does not guarantee that the term refers to anything real. If there are no crosses between owls and frogs, there are no flibbits, and if there are no flibbits, then the question about whether they live in trees is not really a question about some matter of fact. It is no more likely than unlikely that they do. It is false to say that they do live in trees, but we cannot conclude from that that they must live elsewhere. What appears to be a meaningful question turns out not to be so meaningful, after all, since the question isn’t really about anything.

We can think about Hume’s approach as one that requires of us that we have some ground for thinking that there really are existing objects that are referred to by our ideas, before we take any questions that are formulated in terms of these ideas to be serious questions about real existence and matters of fact.


Similar Kinds of Questions 

  • What powers are involved in changing the state of motion or rest in bodies?
  • Are these powers the same as the powers responsible for the transformation of a seed into an oak?
  • Can any natural power explain a caterpillar being changed into a butterfly?
  • Does the necessary connection between cause and effect render the outcome of any and every event necessary?
  • Does the necessary connection between motives for acting and actions make those actions themselves necessary?
  • Does the necessary connection between action and reaction, or between stimulus and response, mean that no other outcomes are even possible?

If we start reasoning in order to come up with answers to these questions in the same way we started reasoning about flibbits, we might come up with any number of different answers that might seem more or less reasonable or probable on the basis of the lines of thinking we employ.

But, wait a minute, ‘flibbits’ wasn’t a genuine idea (or at least it is still under suspicion). How can we go about determining exactly what these questions are or are not asking?

Well, what do we mean by ‘power’, what do we mean by ‘necessary connection’? What makes us so sure that there are such things that we can even ask these questions about? Maybe the terms we use are precisely defined (a power is that in virtue of which something acts; a necessary connection is one that cannot fail to obtain) without actually describing anything that really exists; i.e., we have articulated what something would have to be in order to count as a power or a necessary connection (relations of ideas), but we aren’t sure that there are any such things (as a matter of fact).

Instead of heading down the road of speculative reasonings on the basis of well-defined concepts, we might decide to start by considering the empirical basis for accepting that we can even ask questions and seek answers concerning things that we refer to with terms like ‘power’ and ‘necessary connection’.

Once we have established the source of the ideas involved, we can then ask meaningful questions about the things we are thinking and reasoning about through those ideas.

The source of our idea of power or necessary connection:

External Objects–sense experience of bodies?: No–all we perceive is one state, followed by another state. We do not perceive any supposed connection between these states.

Exercise of mental control over the body?: No–all we perceive is the will or desire to move some part of the body, followed by the movement of that part of the body. We do not perceive any supposed connection between these two.

Exercise of mental control over thoughts?: No–all we perceive is the will or desire to call up some idea, followed by the idea. We do not perceive any supposed connection between these two.

So, maybe we have no idea of connection or power at all…


The impression from which the idea is copied is the feeling of being compelled (or forced) to expect one thing to follow from another, after we have observed similar things to be conjoined through some number of previous cases.

We do not get an impression of power or necessary connection from any single observation of our mind in relation to our own body

We do not get an impression of power or necessary connection from any single observation of our mind in relation to our thoughts and perceptions

We get an impression of power or necessary connection:

when many uniform instances appear, and the same object is always followed by the same event; we then begin to entertain the notion of cause and connexion. We then feel a new sentiment or impression, to wit, a customary connexion in the thought or imagination between one object and its usual attendant; and this sentiment is the original of that idea which we seek for.  (Sect. VII, Part II)

Necessity and Liberty

The source of the idea of necessity:

  • constant conjunction of similar objects
  • mind determined by custom to infer one thing from the appearance of another.

This is what emerges from our experience of inert bodies.

Leads to the view:

“that matter, in all its operations, is actuated by a necessary force, and that every natural effect is so precisely determined by the energy of its cause that no other effect, in such particular circumstances, could possibly have resulted from it”

This is all that we ascribe to matter in terms of necessity (i.e., like events have like causes/effects)

This is also what emerges from our experience of human beings

Human behavior is not, in principle, any less predictable than is the behavior of inert bodies.

We assume constant principles in human nature (ambition, self-love, friendship, generosity, etc.) that provide motives for action in particular situations. For someone to act completely contrary to what our experience suggests that people would do in some particular circumstance, would seem to be just as much a violation of natural laws as if an inert body in motion stopped its own motion or an inert body at rest got up and danced a jig.

Voluntary action does not rule out necessity–nor does a necessary connection between cause and effect rule out causes that act voluntarily (i.e., in accordance with a will, or with a desire for the good that is represented in some action or in its effects).

The source of the idea of liberty:

IDEA = a power of acting or not acting according to the determinations of the will

SOURCE= If we choose to remain at rest, we may; if we choose to move, we also may.

Compatibility of the Two:

The compatibility of the two was never really an issue for the practice of science and the practice of making moral judgments.

Both involve the idea of necessity and causal reasoning concerning matters of fact; moral judgments also involve the idea of liberty–motives and incentives are involved and are contrasted with external forces or constraints–as part of the causal story in relation to which we understand what happened and why, who was responsible, and what should be done in response.

No problem arises there…

It’s only when we get involved in disputes that make use of these ideas in ways that cannot be grounded in experience and common practice that we run into the appearance of incompatibility.

For example:
We go beyond constant conjunction and the determination of the mind to infer cause from effect (or vice versa) to some supposed idea of necessity that warrants claims about the absolute necessity of some existing thing, the absolute necessity of its determinations, the absolute necessity with which effects follow from it, etc. (i.e., Spinoza). That is when we begin to despair concerning the everyday practical conception of ourselves and others as willing, as acting voluntarily, and as responsible for the outcomes of our actions.

We go beyond the lack of external constraint in acting from our desires to some supposed idea of liberty that warrants claims about powers to determine one’s will (or desires) in complete independence from prior causes and external circumstances. That is when we begin to despair concerning the everyday practical conception of ourselves and others as connected with other beings in our desires and actions, and as responsible to them for the outcomes of our actions.

In doing this, we are not making use of well-grounded concepts or ideas for reasoning about matters of fact. We are transforming our well-grounded ideas into absolutes that we can then draw conclusions from simply by using logic to parse out the relations between ideas; however, the results of this enterprise have no real bearing on our actual practices or their legitimacy. The ideas of these absolutes cannot be traced back to impressions, so they lose their connection to proper modes of reasoning concerning real existence and matters of fact.

Brief Reflection before heading into Sections IX -XII
In the section on Liberty and Necessity we really see Hume’s skeptical naturalism taking shape. One of the first things people appeal to in arguing against a thoroughgoing naturalism is human liberty–if this liberty implies the possession of free will, and this is a power that distinguishes the human soul from other causes in nature, then liberty provides a first step beyond natural causes. If liberty does not distinguish human beings from other causes in nature, however, then this step is blocked.

Of the Reason of Animals

There is no difference in kind between human reason and the kinds of cognitive functioning we see in animals.
There is a difference in degree, just as there is a difference in degree between one human and another, but there doesn’t appear to be any good reason to attribute to human beings some power or faculty that is entirely lacking in other animals.
The same principles that appear to account for the behaviors of animals can also account for the behaviors of humans; i.e., Natural Instincts, feelings of pleasure and displeasure, experience of regularities in nature, inferences from past experience to future expectations.
“it is impossible, that this inference of the animal can be founded on any process of argument or reasoning, by which he concludes, that like events must follow like objects, and that the course of nature will always be regular in its operations. For if there be in reality any arguments of this nature… (106)


What is Hume up to here?

Is he arguing against the possibility of miracles? (Why not?)

Is he arguing that we shouldn’t have any beliefs concerning supernatural things? (Why not?)
What do the final paragraphs of the section indicate to us?

“I am the better pleased with the method of reasoning here delivered, as I think it may serve to confound those dangerous friends or disguised enemies to the Christian Religion, who have undertaken to defend it by the principles of human reason. Our most holy religion is founded on Faith, not on reason; and it is a sure method of exposing it to put it to such a trial as it is, by no means, fitted to endure.” (130)
“… we may conclude, that the Christian Religion not only was at first attended with miracles, but even at this day cannot be believed by any reasonable person without one. Mere reason is insufficient to convince us of its veracity: And whoever is moved by Faith to assent to it, is conscious of a continued miracle in his own person, which subverts all the principles of his understanding, and gives him a determination to believe what is most contrary to custom and experience.” (131)

So, the target here appears to be someone who thinks that miracles provide evidence for religious beliefs; i.e., someone who thinks that reasoning consistently on the basis of the evidence for miracles leads us to beliefs about supernatural forces or entities, and that these beliefs are well-grounded in experience and understanding.

p1) Outcome x occurs in situation A

p2) The laws of nature determine that not-x should be the outcome of situation A

C1) Therefore, the occurrence of x in A is a violation of the laws of nature

def.) A miracle is a violation of the laws of nature

C2) Therefore, the occurrence of x in A is a miracle

p3) If miracles occur, then I am rationally justified in believing in supernatural powers

C3) I am rationally justified in believing in supernatural powers

Hume’s point here is not about the belief in miracles per se. Instead, it is about our rational warrant for believing any reports of miracles.

If we read about a miracle in the Bible, or in some other religious text, or we hear someone claiming to have witnessed some miracle, our reasoning about the case at hand, according to our common methods of evaluating evidence, will inevitably prevent us from believing the report.

If we decide to believe the report and accept the testimony, then it has to be that we are depending on something other than our experience and understanding in our decision. So, anyone who doesn’t find it simply absurd to accept the truth of these reports, must already be oriented towards determining grounds for belief other than those provided by experience and understanding.

It would, then, be false for such a person to claim that his or her belief in the miracles of Christianity is grounded solely in these things; i.e., that any fair and impartial judge would be led by the evidence to conclude that these claims about miracles must be true.

So, why is this, according to Hume?

  • Relying solely on experience and understanding, we operate with the assumption that whatever happens follows the course of nature.
  • When some event occurs that violates our expectations, we look first for other natural explanations of the event (e.g., something we didn’t notice in forming that expectation)
  • We don’t go directly to the claim that what occurred violates the laws of nature (remember, our grasp of these laws is based on experience and experiment, and every new experience potentially adds to our understanding of what the laws of nature are)
  • In order for us to accept that some miracle has occurred, the evidence for its occurrence has to outweigh all the contrary evidence–it has to be so convincing that it forces us to give up the assumption that whatever happens follows the course of nature.
  • If we aren’t willing to give up this assumption, we can always use it to discount the testimonial evidence we are given for the occurrence of a miracle.
    • From my perspective, on the basis of my experience and understanding, I know that people sometimes make up stories, or misinterpret what they are seeing.
    • From my perspective, on the basis of my experience and understanding, I do not know that miracles sometimes occur.
    • Accordingly, when I weigh the probability that the person reporting the event is making up a story or has misinterpreted what they saw vs. the probability that a miracle has actually occurred, I am always going to come down on the side of the testimony being false in some way.

If my trust is entirely in my experience and understanding, then there will never be a witness that I deem to be so trustworthy as to allow myself to be convinced concerning their testimony (at least not when accepting it would conflict with beliefs that I have formed through my trusted sources).

Okay, so the person who chooses to be guided only by experience and understanding will never come to accept Christianity on the basis of an appeal to miracles.

Are there other ways of convincing such a person? What about convincing them of at least some of the basic claims by appeal to the order of nature itself? Does the order of nature imply the existence of a supreme being? Does it imply that this being is wise and good? Does it imply a moral order and/or a future life for human being?

Hume on the Existence of God and the Immortality of the Soul

Claims about the existence of God and the immortality of the soul are claims about matters of fact (i.e., they concern whether or not there is some existing thing that has some quality or qualities).

Reasoning about matters of fact requires that we use the relation of cause and effect

The knowledge concerning causes and effects that we need in order to reason from the existence of one thing to the existence of some other thing is a product of experience

The source of our reasoning about what we don’t experience on the basis of what we have experienced is not some clear insight concerning the necessity that these things resemble each other; it is the habit or custom of expecting something or anticipating something–which is more than just having an idea of it–it is having an idea of it that is forceful and vivid enough that we don’t even imagine any alternate outcomes (despite the fact that reason doesn’t allow us to rule out these other outcomes–i.e., they remain logically possible outcomes). It is having an idea that compels our assent (the sun will rise; the fire will burn; the billiard ball will move)

When we consider what beliefs concerning matters of fact a reasonable person will have, they fall into two general categories:

  1. Those concerning objects of their own experience
  2. Those based on reasonings that start from objects of experience and proceed according to relations of cause and effect that are grounded in experience

If we think about the existence of God and the immortality of the soul along these lines, we could rely on:

  1. Our own experience of these things
  2. Reasoning about them that is grounded in our own experience

If we have 1), that’s great. We have no doubts for ourselves. But what about people who have doubts? Can they be convinced of these things through reason, as Descartes insisted that they could be?

Miracles: Particular events that appear to defy the laws of nature
Reason is always going to come down on the side of natural causes and natural ignorance when it comes to dealing with particular events. Did the bush really speak? I wasn’t there, so I am going to reason about the claim that it did… other possible explanations are never going to be ruled out if I stick to principles of sound reasoning. Maybe it was a hallucination; maybe the actual story has been modified; maybe the whole thing was made up. If I already have faith, I might allow more authority to the Bible than I do to my own experience and reasoning, but the question was about someone who didn’t already have faith.


The order of nature: The beauty and regularity of particular natural arrangements
Reason may lead us to think of some cause of these features of nature that works in ways different from the random motions, collisions, and aggregations of atoms. It does not, however, allow us to conclude anything about this cause for which there is not sufficient evidence discovered in nature.

This means that the argument from design doesn’t get us anywhere near the conclusions that it is offered to justify:

  • We can reason about nature according to the idea of an intelligent, powerful, and good cause, but we cannot conclude that this cause is omniscient, omnipotent, or omnibenevolent.
  • If the world were experienced to be perfectly beautiful and perfectly regular we might then be entitled to conclude that its cause is perfect; but, it isn’t. There is beauty and ugliness; there is regularity and chaos; there is justice and injustice.
  • This imperfection in the effect should lead us to conclude that there is imperfection in the cause (again, if we are sticking with rules of reasoning).

But, what if we were to say, “okay, but we only perceive parts of the whole–the whole is, in fact, perfect, and as such, its cause must be perfect”.

  • If the order of nature is imperfect; if there is no perfect correspondence between being good and being rewarded, and between being evil and being punished, in nature there must be another order of created things where justice is served.
  • This means that the death of the body in the natural course of things is not necessarily the death of the person–perhaps the person is destined to live on in some state that lacks the imperfections of the natural world.

The reply to this would be to remind ourselves that the only grounds for our claims about the whole in this case are provided by our experience of the parts. We could hypothesize that the whole may be perfect, but that isn’t something we arrive at through reasoning on the basis of experience and legitimate inferences concerning cause and effect. Again, if this commitment is operative in our own thinking and believing, it must have some source other than experience and reason.

Hume on Skepticism

Antecedent–can’t be carried as far as Descartes claims to, but is a good methodology for rational inquiry. No need to worry about pernicious effects.

Consequent–scientific view of the world undermines common sense views; undermines belief in liberty and moral accountability; undermines belief in authority, etc. This kind of scepticism cannot be maintained when it comes to action–we all live as dogmatists, even if we become sceptics when we do philosophy; the natural inclinations to believe and act always overcome theoretical and speculative considerations–even in those who are most prone to take an interest in them. So, again, no need to worry about effects.

Mitigated (academic)–when nature has freed us from our most extreme doubts, we have a clearer sense of our abilities and their limits, and of the need to rely on things other than direct experience and scientifically legitimate reason for everyday living.


Questions about Hume’s Enquiry

Why start there?
Perceptions of the Mind = Impressions and Ideas; distinguished by reference to force and vivacity; Ideas are copies of impressions

The distinction is an intuitively plausible one (e.g., when I perceive something hot, I have an impression of the thing and an impression of heat that are forceful and vivid; I can then do things like recall that experience and perceive the same state of affairs in a much less forceful and vivid way–the latter can be called having an idea, okay)

There is also some historical precedent for it.

But, what about the view makes it philosophically compelling?

Why insist that the idea is a perception of the mind? If the mind is recalling the state of affairs, and then we have the object before the mind in a way that is so different than the way we experience it when we are actually having a sensible impression, then couldn’t we say the mind is engaged in act of thinking?

Maybe there isn’t such a great difference between perceiving and thinking; but if that’s the case, then we might need to appeal to the mind as something more substantive that is capable of doing both, instead of treating both in a way that makes it seem more like something is happening to us.

What does it mean for an idea to be a copy of an impression?

Again, in general, we can make sense of one thing being a copy of another; we can even make sense of one thing being copied from another and, yet, being fainter and less vivid than the original.

But, what does it mean for one perception of the mind to be a copy of another perception of the mind? If they are events, I can understand that there is some resemblance between them, but how can an event be a copy of another event? If they are actions, the same question arises.

Why should we accept that ideas or representations that present things to us as being complex are themselves complex ideas or representations?

Do representations have parts in the same way that we think of bodies as having parts?

Can we analyze a representation into its constituent parts, hang on to these parts, and then combine them with other parts in different ways?

This assumption is one that Locke and others also make, but maybe it is one that we are better of not accepting. Conscious awareness and representations of objects clearly have a variety of modes or aspects, but it is not at all clear that they have distinct parts that correspond to the different parts of the objects we perceive and/or think about.

Why isn’t Hume simply begging the question against Descartes concerning the origin of our ideas?

Descartes claims that some ideas cannot be generated in the way Hume claims they are. Where is Hume’s argument that shows us that Descartes is wrong about that? (Or are we just supposed to accept that Descartes shouldn’t be taken seriously here?) Whence this capacity for unlimited augmentation of qualities? (look at the argument he offers… p. 19)


At bottom, it isn’t clear that Hume’s model of the mind is sophisticated enough for him to be able to account for all the features of our experience that he takes for granted.

Without any explanation of how, he assumes that we have experience of spatially and temporally ordered series of events of similar kinds, through which we come to develop habits of anticipation. We can determine what happens first, then what happens, next, etc… How does this come about simply through impressions? Can’t I have some series of impressions where the order in which I perceive things does not correspond to an objective order of events? How do we distinguish between the subjective order of our impressions and the (supposed) objective order of the events we take ourselves to know about through these?

He assumes that we do this in such a way that habits or customs of perceiving explain the judgments we make concerning matters of fact in particular cases, and then provide the framework for reasoning about other cases. Again, how these behaviors can be explained by reference to impressions and ideas is not entirely clear.

Are these questions/criticisms fair to Hume?
Maybe he isn’t trying to provide an account of these things. They do occur; we cannot give an account of how they occur; the best we can do is recognize that certain ideas and patterns of thinking become available to us at particular times in our experience, describe this process to some extent, and use this awareness as a way of guarding against false security concerning the status of these ideas and ways of thinking.

But, if that is the case, does Hume really have the right to deny any of the claims of other philosophers that differ from his own? For example, can he rule out the possibility that there are basic functions of judgment that are features of the way minds work and, as such, cannot be derived from experience? The fact that I first become aware of something at time T2, through my experience, does not necessarilly mean that it did not already exist prior to then, at T1, and play a role in making the experience through which I become aware of it possible… does it?