Lecture 4 The Paleolithic period (or Old Stone Age) is The Paleolithic period (or Old Stone Age) is

the earliest period of human development. the earliest period of human development. Dating from about 2 million years ago, and Dating from about 2 million years ago, and ending in various places between 50,000 and ending in various places between 50,000 and 10,000 years ago, it is roughly co-extensive 10,000 years ago, it is roughly co-extensive with the geologic period known as the with the geologic period known as the Pleistocene, an epoch which was marked by Pleistocene, an epoch which was marked by continuous cooling, which resulted in several continuous cooling, which resulted in several ice ages. During the period, hominids become ice ages. During the period, hominids become increasingly advanced in terms of fire and tool increasingly advanced in terms of fire and tool making, and modern humans emerge.making, and modern humans emerge.

Lecture 4 Evidence of Cro-Magnon humans (one of several Evidence of Cro-Magnon humans (one of several

varieties of modern humans that lived during the varieties of modern humans that lived during the period) indicates they lived some 50,000-10,000 period) indicates they lived some 50,000-10,000 years ago. Anatomically the same as today’s years ago. Anatomically the same as today’s Homo Homo sapienssapiens and fossil remains, graves, artifacts, and and fossil remains, graves, artifacts, and dwellings have been found throughout Europe.dwellings have been found throughout Europe.

It is believed that their arrival in Europe, when they It is believed that their arrival in Europe, when they encountered another hominid species, the encountered another hominid species, the Neanderthals, resulted in the extinction of the latter.Neanderthals, resulted in the extinction of the latter.

In a recent article in “The Science Times,” a regular In a recent article in “The Science Times,” a regular feature of feature of The New York TimesThe New York Times’ Tuesday addition, it ’ Tuesday addition, it was hypothesized that Cro-Magnons were so startled was hypothesized that Cro-Magnons were so startled to be confronted with another bi-pedal, tool using to be confronted with another bi-pedal, tool using (and much larger!) hominid, that they developed the (and much larger!) hominid, that they developed the practice of designing beads that would identify them. practice of designing beads that would identify them.

Lecture 4

Which of the following examples that Which of the following examples that scientists cited in the film as evidence of the scientists cited in the film as evidence of the existence of modern humans at particular sites existence of modern humans at particular sites did you find convincing? Unconvincing (a did you find convincing? Unconvincing (a stretch)? Or you’re unsure? Consider both the stretch)? Or you’re unsure? Consider both the physical evidence and the reasoning from it to physical evidence and the reasoning from it to a hypothesis about the birth of the human a hypothesis about the birth of the human mind, human creativity, and/or human mind, human creativity, and/or human expression?expression?

The discovery of what scientists call “beads”The discovery of what scientists call “beads” The differences in the treatment that humans and The differences in the treatment that humans and

Neanderthals provided the dead?Neanderthals provided the dead? Cave paintings?Cave paintings? Fossil evidence (particularly skulls) of Neanderthals and Fossil evidence (particularly skulls) of Neanderthals and

humans?humans? Real and relatively quick innovations (in, for example, Real and relatively quick innovations (in, for example,

spears and spear heads)?spears and spear heads)? Migrations of early humans across Europe?Migrations of early humans across Europe? Cave instruments and music?Cave instruments and music? Biological changes in the brain?Biological changes in the brain? Comparison of humans and chimpanzees?Comparison of humans and chimpanzees? The emergence and significance of language?The emergence and significance of language? Cultural forces overriding biological forces?Cultural forces overriding biological forces?

Demarcation: Ayer and “verifiabiliity” Although Ayer doesn’t single out science (his Although Ayer doesn’t single out science (his

immediate target is a form of metaphysics), his immediate target is a form of metaphysics), his criterion of “verifiability” was adopted for a time by criterion of “verifiability” was adopted for a time by scientists and philosophers of science as a criterion of scientists and philosophers of science as a criterion of demarcation between science and “pseudo-science” demarcation between science and “pseudo-science” (and “non-science” – e.g., the arts)(and “non-science” – e.g., the arts)

A statement (hypothesis or theory) is genuinely A statement (hypothesis or theory) is genuinely meaningful (genuinely scientific) only if it is able to meaningful (genuinely scientific) only if it is able to be verified by experience.be verified by experience.

His immediate goal: to show that statements His immediate goal: to show that statements (hypotheses or theories) that are not verifiable are (hypotheses or theories) that are not verifiable are “nonsense” (pseudo-scientific).“nonsense” (pseudo-scientific).

Demarcation: Ayer and “verifiabiliity” As claims about a so-called transcendental As claims about a so-called transcendental

reality are, in principle, not empirical (based reality are, in principle, not empirical (based on sensory experience), why not just go after on sensory experience), why not just go after the kinds of the kinds of argumentargument that are supposed to that are supposed to support them?support them?

For one thing, one might be willing to say that For one thing, one might be willing to say that one’s statements are not based on sensory one’s statements are not based on sensory experience … but are rather the product of the experience … but are rather the product of the cognitive capacity of “intuition”cognitive capacity of “intuition”

So they refuse to accept the grounds of the So they refuse to accept the grounds of the objection.objection.

Demarcation: Ayer and “verifiabiliity” For another, one cannot demonstrate that an For another, one cannot demonstrate that an

argument is argument is invalidinvalid by demonstrating that its by demonstrating that its conclusion is conclusion is falsefalse..

Remember that validity does not rule out false Remember that validity does not rule out false premises or false conclusions, only arguments premises or false conclusions, only arguments in which in which it is possibleit is possible for the premises to be for the premises to be true and the conclusion false.true and the conclusion false.

Valid argumentsValid arguments can have true premises and a can have true premises and a true conclusion; false premises (one or more) true conclusion; false premises (one or more) and a false conclusion; false premises (one or and a false conclusion; false premises (one or more) and a true conclusion.more) and a true conclusion.

Demarcation: Ayer and “verifiabiliity” A valid argumentA valid argument

All men are green.All men are green. Socrates is a man.Socrates is a man.

-------------------------------------------- Socrates is green.Socrates is green.

An invalid argumentAn invalid argument All men are mortal.All men are mortal. Socrates is mortal.Socrates is mortal.

---------------------------------------------- Socrates is a man.Socrates is a man.

Demarcation: Ayer and “verifiabiliity” So the most useful way to demonstrate that some So the most useful way to demonstrate that some

statement (or hypothesis or theory) is not meaningful statement (or hypothesis or theory) is not meaningful (cognitively significant) or is nonsense is to show that (cognitively significant) or is nonsense is to show that it cannot be verified by any sensory experiences.it cannot be verified by any sensory experiences.

Verifiable: a statement is verifiable only if we can Verifiable: a statement is verifiable only if we can identify what observations would show a sentence to identify what observations would show a sentence to be true.be true.

Instead of arguing for or against the nature of the Instead of arguing for or against the nature of the mind, focus on “the literal significance of language”mind, focus on “the literal significance of language”

Metaphysicians fail to produce sentences which Metaphysicians fail to produce sentences which conform to the conditions under which alone a conform to the conditions under which alone a sentence can be “literally significant.”sentence can be “literally significant.”

Demarcation: Ayer and “verifiabiliity” Part of Ayer’s argument:Part of Ayer’s argument:

Distinguish between “propositions” and Distinguish between “propositions” and “sentences”“sentences”

Propositions are what sentences expressPropositions are what sentences express For example, sentences of different languages might For example, sentences of different languages might

express the same proposition (e.g., “It is currently express the same proposition (e.g., “It is currently raining here”)raining here”)

Demonstrate that some kinds of sentence do not Demonstrate that some kinds of sentence do not express a genuine proposition about “a matter of express a genuine proposition about “a matter of fact”.fact”.

Demarcation: Ayer and “verifiabiliity” Part of Ayer’s argument:Part of Ayer’s argument:

Distinguish between “practical verifiability” and Distinguish between “practical verifiability” and “verifiability in principle”“verifiability in principle”

An example: “There are mountains on the dark An example: “There are mountains on the dark side of the Moon.”side of the Moon.”

Another: “There is little red schoolhouse on the far Another: “There is little red schoolhouse on the far side of the Moon.”side of the Moon.”

Although neither is Although neither is practically verifiablepractically verifiable, both are , both are verifiable in principleverifiable in principle..

His criterion of “verifiability” appeals to His criterion of “verifiability” appeals to “verifiable in principle”“verifiable in principle”

Demarcation: Ayer and “verifiabiliity” Part of Ayer’s argument:Part of Ayer’s argument:

A distinction between a “strong” and “weak” sense A distinction between a “strong” and “weak” sense of “verifiable”of “verifiable”

The strong sense: show that a sentence is such that The strong sense: show that a sentence is such that (it or the proposition it expresses) can be shown to (it or the proposition it expresses) can be shown to be be truetrue..

The weak sense: show that a sentence is such that The weak sense: show that a sentence is such that (it or the proposition it expresses) can be shown to (it or the proposition it expresses) can be shown to be be probableprobable..

Some argue for the former, but that would rule out Some argue for the former, but that would rule out things like “laws of nature”.things like “laws of nature”.

Accordingly, he opts for the weak sense.Accordingly, he opts for the weak sense.