John Locke Empiricism

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					John Locke‟s Empiricism

A Theory of Knowledge in Contrast
  to Descartes‟ Rationalism and
                John Locke
• John Locke (1632-1704) also lived during the
  Scientific Revolution.
• However, Locke was not an impressed with the
  geometric method as a model for knowledge as
  Descartes was.
• Rather, Locke was influenced by the experimental
  method of the „new‟ sciences as used by thinkers
  like Robert Boyle and Isaac Newton.
• Locke does not mean quite the same thing we
  do when he speaks of „ideas‟:
• “Whatsoever the mind perceive in itself or is
  the immediate object of perception, thought, or
  understanding, that I call „idea‟.”
• Sometimes we will use „idea‟, „sensation‟,
  „perception‟, and „sense perception‟
  interchangeably; although Locke also includes
  the content of thoughts as „ideas‟.
                 Innate Ideas
• Unlike Descartes, Locke argues that we do not
  have any innate ideas. At birth, our minds are like
  “white paper, void of all character without any
• This applies both to what he calls “speculative”
  principles (those pertaining to the nature of
  reality) and “practical” principles (moral truths).
• Locke‟s argument against innate ideas begins by
  considering the innateness of necessary truths like
  the Law of Non-Contradiction.
              Innate Ideas
• The Law of Non-Contradiction says that the
  same statement cannot be both true and
• This is just the kind of principle that
  Descartes took to be self-evident and known
  through intuition.
• But Locke wants to know what evidence
  there is that the Law of Non-Contradiction
  is innate.
               Innate Ideas
• He considers three possibilities:
• First, the fact that they are universally
  agreed to is evidence that they are innate.
• Second, their innateness implies that they
  are understood to be true by children.
• Third, the fact that they are known only
  through reason is evidence of their
                 Innate Ideas
• Locke denies that principles like the Law of Non-
  Contradiction are universally agreed to.
• But even if they were universally agreed to, that
  wouldn‟t make them innate.
• That‟s because we can all agree that some
  principles are true even though those principles
  are only known through experience (like the
  principle that the earth revolves around the sun).
              Innate Ideas
• Second, Locke argues, if these principles
  were innate, then they‟d be understood to be
  true by children; but Locke says this
  obviously isn‟t the case.
• Finally, the fact that such principles are
  known only through reason does not show
  that they are innate.
                 Innate Ideas
• For one thing, if everything known through reason
  alone were innate, then all mathematical truths
  would be innate because they are all known
  through reason.
• But even rationalists would agree that not all
  mathematical truths are innate (if they were, then
  subjects like calculus and differential equations -
  and even yet-to-be-discovered subjects - would all
  be innately known).
           The Origin of Ideas
• So, Locke dismisses the claim that we are born
  with some ideas.
• He replaces this claim with another: that all of our
  ideas originate in experience.
• But Locke thinks there are different kinds of ideas,
  and that they have different sources.
• While Locke‟s complete taxonomy of ideas is
  very complex, we can discuss two of his most
  important distinctions.
       Sensation and Reflection
• According to Locke, our ideas come from
  experience in two ways.
• First, ideas enter the mind through our senses.
  Locke calls this sensation.
• Second, our we have experiences of our minds‟
  own operations (like thinking, willing, believing,
  and desiring). Locke calls this reflection.
• All of our ideas ultimately come from sensation
  and reflection - including knowledge of our own
    Simple and Complex Ideas
• Locke also distinguishes between simple and
  complex ideas.
• A simple idea is “uncompounded, contains
  nothing but one uniform appearance or
  conception in the mind, which is not
  distinguishable into different ones.”
• A complex idea is composed of simple ideas.
• The idea RED is a simple idea, whereas „red
  shoe‟ is a complex idea.
                Abstract Ideas
• The simple ideas received from sensation are
  always particulars: We perceive this particular
  shape or that particular color.
• We also have a capacity that Locke calls
  abstraction (recall Aquinas).
• This is the mental ability to convert particular
  simple ideas into universal or general ideas - an
  idea of a triangle in general or of tables in general.
          Ideas and Qualities
• The challenge for Locke is to explain how
  our ideas (which are only in our minds) give
  us knowledge of objects that exist beyond
  them - ordinary physical objects such as
  tables and chairs - as well as scientific
• He explains this by arguing that our ideas
  represent real qualities of things.
• For Locke, a Quality is a property of an
  external object.
• A Primary Quality is an intrinsic property of
  any material object, whether or not it is
  perceived. These qualities are “utterly
  inseparable from the body in what sate soever
  it may be.”
• A Secondary Quality is the power of objects to
  produce certain ideas in our minds “by the
  operation of insensible particles on our
• Examples of primary qualities are shape,
  extension, solidity, motion and number.
• Examples of secondary qualities are colors,
  sounds, tastes, smells, and textures.
• Secondary qualities are not in the objects
  themselves but are merely “the power to
  produce various sensations in us by their
  primary qualities.”
 Representation & Resemblance
• According to Locke, ideas represent qualities by
  resembling them.
• The ideas of primary qualities resemble the
  qualities themselves, but the ideas of secondary
  qualities resemble nothing in objects themselves.
• Our ideas of colors and sounds do not resemble
  the secondary qualities, nor do they resemble the
  primary qualities that are the ground of these
  secondary qualities.
   Knowing the External World
• But if our ideas of colors, tastes, sounds,
  odors and textures do not resemble the real
  qualities of external objects, how can the
  former give us knowledge of the latter?
• Locke gives at least four arguments for the
  claim that our sensory experiences provide
  us with evidence for the existence of
  external objects and their characteristics.
    Knowing the External World
Locke‟s first argument is the following:
  “First, because we cannot have ideas of sensation but by the inlet of
  the senses. It is plain those perceptions are produced in us by exterior
  causes affecting our senses: because those that want the organs of any
  sense, never can have the ideas belonging to that sense produced in
  their minds. This is too evident to be doubted: and therefore we cannot
  but be assured that they come in by the organs of that sense, and no
  other way. The organs themselves, it is plain, do not produce them: for
  then the eyes of a man in the dark would produce colours, and his nose
  smell roses in the winter: but we see nobody gets the relish of a
  pineapple, till he goes to the Indies, where it is, and tastes it.” (E
• Locke‟s argument here can be
  reconstructed as follows:
  1. If visual experiences were caused by the eyes
     (or, presumably, by the mind) of the person
     having them, then blind people would have
     visual experiences.
  2. Blind people do not have visual experiences.
  3. Therefore, visual experiences are not caused
     by the eyes (or the mind) of the person having
• Locke intends similar arguments to apply
  to all other sensory modalities.
    Knowing the External World
• Locke‟s second argument is as follows:
  “Secondly, Because we find that an idea from actual sensation, and another
  from memory, are very distinct perceptions. Because sometimes I find that I
  cannot avoid the having those ideas produced in my mind. For though, when
  my eyes are shut, or windows fast, I can at pleasure recall to my mind the
  ideas of light, or the sun, which former sensations had lodged in my memory;
  so I can at pleasure lay by that idea, and take into my view that of the smell of
  a rose, or taste of sugar. But, if I turn my eyes at noon towards the sun, I
  cannot avoid the ideas which the light or sun then produces in me. So that
  there is a manifest difference between the ideas laid up in my memory, (over
  which, if they were there only, I should have constantly the same power to
  dispose of them, and lay them by at pleasure,) and those which force
  themselves upon me, and I cannot avoid having. And therefore it must needs
  be some exterior cause, and the brisk acting of some objects without me,
  whose efficacy I cannot resist, that produces those ideas in my mind, whether I
  will or no.” (E IV.xi.5)
Locke‟s argument here may be
reconstructed as follows:
1. If I have a visual experience, then it must have
   a cause.
2. If I caused my visual experience, then I can
   control which visual experiences I have.
3. I cannot always control which visual
   experiences I have.
4. Therefore, I do not cause all of my visual
5. Therefore, some of my visual experiences
   must have an external cause.
   Knowing the External World
• Locke‟s third argument is as follows:
  “Thirdly, because pleasure or pain, which accompanies actual
  sensation, accompanies not the returning of those ideas without the
  external objects. Add to this, that many of those ideas are produced in
  us with pain, which afterwards we remember without the least offence.
  Thus, the pain of heat or cold, when the idea of it is revived in our
  minds, gives us no disturbance; which, when felt, was very
  troublesome; and is again, when actually repeated: which is occasioned
  by the disorder the external object causes in our bodies when applied
  to them: and we remember the pains of hunger, thirst, or the headache,
  without any pain at all; which would either never disturb us, or else
  constantly do it, as often as we thought of it, were there nothing more
  but ideas floating in our minds, and appearances entertaining our
  fancies, without the real existence of things affecting us from abroad.”
  (E IV.xi.6)
This argument can be reconstructed as
1. If there is a difference between having a
   headache and remembering a headache, then
   they must have different causes.
2. There is a difference between having a
   headache (which is painful) and remembering
   a headache (which is not painful)
3. Therefore, they have different causes (an
   external cause when having it, my mind when
   remembering it).
    Knowing the External World
• The fourth and last argument Locke gives is as
  “Fourthly, because our senses assist one another's testimony of the
  existence of outward things, and enable us to predict. Our senses in
  many cases bear witness to the truth of each other's report, concerning
  the existence of sensible things without us. He that sees a fire, may, if
  he doubt whether it be anything more than a bare fancy, feel it too; and
  be convinced, by putting his hand in it. Which certainly could never be
  put into such exquisite pain by a bare idea or phantom, unless that the
  pain be a fancy too: which yet he cannot, when the burn is well, by
  raising the idea of it, bring upon himself again.” (E IV.xi.7)
   This last argument may be reconstructed
   as follows:
1. Repeated observation has shown me that
   ideas of different senses that I experience
   as closely correlated likely have the same
   cause (and since I know that I didn‟t cause
   them, they have an external cause).
2. Therefore, the closely correlated ideas of
   different senses that I currently experience
   likely have the same external cause.