Ideas from 'Language,Truth and Logic' by A.J. Ayer [1936], by Theme Structure

[found in 'Language, Truth and Logic' by Ayer,A.J. [Penguin 1974,0-14-021200-0]].

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1. Philosophy / D. Nature of Philosophy / 3. Philosophy Defined
Philosophy is a department of logic
1. Philosophy / D. Nature of Philosophy / 4. Aims of Philosophy / e. Philosophy as reason
Philosophers should abandon speculation, as philosophy is wholly critical
1. Philosophy / E. Nature of Metaphysics / 6. Against Metaphysics
Humeans rejected the a priori synthetic, and so rejected even Kantian metaphysics
1. Philosophy / F. Analytic Philosophy / 5. Against Analysis
Critics say analysis can only show the parts, and not their distinctive configuration
1. Philosophy / G. Scientific Philosophy / 3. Scientism
Philosophy deals with the questions that scientists do not wish to handle
3. Truth / H. Deflationary Truth / 2. Deflationary Truth
We cannot analyse the concept of 'truth', because it is simply a mark that a sentence is asserted
6. Mathematics / C. Sources of Mathematics / 6. Logicism / a. Early logicism
Maths and logic are true universally because they are analytic or tautological
7. Existence / A. Nature of Existence / 1. Nature of Existence
Positivists regard ontology as either meaningless or stipulated
11. Knowledge Aims / B. Certain Knowledge / 1. Certainty
Only tautologies can be certain; other propositions can only be probable
11. Knowledge Aims / C. Knowing Reality / 2. Phenomenalism
Logical positivists could never give the sense-data equivalent of 'there is a table next door'
Material things are constructions from actual and possible occurrences of sense-contents
12. Knowledge Sources / A. A Priori Knowledge / 4. A Priori as Necessities
We could verify 'a thing can't be in two places at once' by destroying one of the things
12. Knowledge Sources / A. A Priori Knowledge / 5. A Priori Synthetic
Whether geometry can be applied to reality is an empirical question outside of geometry
12. Knowledge Sources / A. A Priori Knowledge / 7. A Priori from Convention
By changing definitions we could make 'a thing can't be in two places at once' a contradiction
12. Knowledge Sources / A. A Priori Knowledge / 8. A Priori as Analytic
To say that a proposition is true a priori is to say that it is a tautology
12. Knowledge Sources / B. Perception / 4. Sense Data / a. Sense-data theory
Positivists prefer sense-data to objects, because the vocabulary covers both illusions and perceptions
12. Knowledge Sources / B. Perception / 7. Causal Perception
Causal and representative theories of perception are wrong as they refer to unobservables
12. Knowledge Sources / C. Rationalism / 1. Rationalism
The main claim of rationalism is that thought is an independent source of knowledge
12. Knowledge Sources / D. Empiricism / 1. Empiricism
Empiricism lacked a decent account of the a priori, until Ayer said it was entirely analytic
All propositions (especially 'metaphysics') must begin with the senses
My empiricism logically distinguishes analytic and synthetic propositions, and metaphysical verbiage
12. Knowledge Sources / D. Empiricism / 4. Pro-Empiricism
It is further sense-experience which informs us of the mistakes that arise out of sense-experience
12. Knowledge Sources / D. Empiricism / 5. Empiricism Critique
Empiricism, it is said, cannot account for our knowledge of necessary truths
14. Science / C. Induction / 2. Aims of Induction
The induction problem is to prove generalisations about the future based on the past
14. Science / C. Induction / 3. Limits of Induction
We can't use the uniformity of nature to prove induction, as that would be circular
15. Nature of Minds / A. Nature of Mind / 4. Other Minds / b. Scepticism of other minds
Other minds are 'metaphysical' objects, because I can never observe their experiences
15. Nature of Minds / A. Nature of Mind / 4. Other Minds / c. Knowing other minds
A conscious object is by definition one that behaves in a certain way, so behaviour proves consciousness
16. Persons / E. Self as Mind / 4. Associated Self
If the self is meaningful, it must be constructed from sense-experiences
16. Persons / F. Self as Body / 1. Role of the Body
Two experiences belong to one self if their contents belong with one body
Empiricists can define personal identity as bodily identity, which consists of sense-contents
17. Mind and Body / A. Mind-Body Dualism / 8. Dualism of Mind Critique
The supposed 'gulf' between mind and matter is based on the senseless concept of 'substances'
19. Language / B. Meaning / 3. Meaning as Verification
Tautologies and empirical hypotheses form the entire class of significant propositions
A sentence is factually significant to someone if they know how to verify its proposition
Factual propositions imply (in conjunction with a few other premises) possible experiences
22. Metaethics / C. Sources of Ethics / 3. Intuitionism
Moral intuition is worthless if there is no criterion to decide between intuitions
22. Metaethics / C. Sources of Ethics / 4. Expressivism
To say an act is wrong makes no further statement about it, but merely expresses disapproval
28. God / A. Divine Nature / 4. Divine Contradictions
A person with non-empirical attributes is unintelligible.
28. God / C. Proofs of Reason / 2. Ontological Proof critique
When we ascribe an attribute to a thing, we covertly assert that it exists
28. God / E. Attitudes to God / 4. Atheism
If theism is non-sensical, then so is atheism.
29. Religion / A. Religious Thought / 3. Religious Verification
The 'truths' expressed by theists are not literally significant