Ideas of A.J. Ayer, by Theme

[British, 1910 - 1989, Born London. Taught by Gilbert Ryle. Visited Vienna Circle in early 1930s. Professor at Universities of London and Oxford.]

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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
2. Reason / E. Argument / 3. Analogy
You can't infer that because you have a hidden birth-mark, everybody else does
2. Reason / F. Fallacies / 1. Fallacy
Induction assumes some uniformity in nature, or that in some respects the future is like the past
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
5. Theory of Logic / F. Referring in Logic / 1. Naming / d. Singular terms
Russell rewrote singular term names as predicates
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
7. Existence / D. Theories of Reality / 10. Ontological Commitment / b. Commitment of quantifiers
It is currently held that quantifying over something implies belief in its existence
9. Objects / D. Essence of Objects / 3. Individual Essences
We see properties necessary for a kind (in the definition), but not for an individual
11. Knowledge Aims / B. Certain Knowledge / 1. Certainty
Only tautologies can be certain; other propositions can only be probable
11. Knowledge Aims / B. Certain Knowledge / 6. Cogito Critique
Knowing I exist reveals nothing at all about my nature
To say 'I am not thinking' must be false, but it might have been true, so it isn't self-contradictory
'I know I exist' has no counterevidence, so it may be meaningless
11. Knowledge Aims / C. Knowing Reality / 2. Phenomenalism
Modern phenomenalism holds that objects are logical constructions out of sense-data
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
No one has defended translational phenomenalism since Ayer in 1940
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
The concept of sense-data allows us to discuss appearances without worrying about reality
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
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / c. Empirical foundations
Basic propositions refer to a single experience, are incorrigible, and conclusively verifiable
14. Science / A. Basis of Science / 6. Falsification
We only discard a hypothesis after one failure if it appears likely to keep on failing
14. Science / C. Induction / 2. Aims of Induction
The induction problem is to prove generalisations about the future based on the past
Induction passes from particular facts to other particulars, or to general laws, non-deductively
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
Maybe induction could never prove the existence of something unobservable
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
The argument from analogy fails, so the best account of other minds is behaviouristic
Originally I combined a mentalistic view of introspection with a behaviouristic view of other minds
Physicalism undercuts the other mind problem, by equating experience with 'public' brain events
The theory of other minds has no rival
16. Persons / C. Self-Awareness / 2. Self-Knowledge
Self-consciousness is not basic, because experiences are not instrinsically marked with ownership
16. Persons / C. Self-Awareness / 3. Undetectable Self
We identify experiences by their owners, so we can't define owners by their experiences
16. Persons / D. Self and Body / 5. Role of the Body
Consciousness must involve a subject, and only bodies identify subjects
People own conscious states because they are causally related to the identifying body
Bodily identity and memory work together to establish personal identity
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
16. Persons / E. Self as Mind / 1. Self and Memory
Not all exerience can be remembered, as this would produce an infinite regress
16. Persons / E. Self as Mind / 3. Psychological Self critique
Temporal gaps in the consciousness of a spirit could not be bridged by memories
16. Persons / E. Self as Mind / 4. Associated Self
Memory is the best proposal as what unites bundles of experiences
If the self is meaningful, it must be constructed from sense-experiences
Personal identity can't just be relations of experiences, because the body is needed to identify them
Qualia must be united by a subject, because they lead to concepts and judgements
Is something an 'experience' because it relates to other experiences, or because it relates to a subject?
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'
17. Mind and Body / E. Mind as Physical / 1. Physical Mind
Why shouldn't we say brain depends on mind? Better explanation!
19. Language / A. Nature of Meaning / 5. Meaning as Verification
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
Tautologies and empirical hypotheses form the entire class of significant propositions
A statement is meaningful if observation statements can be deduced from it
Directly verifiable statements must entail at least one new observation statement
The principle of verification is not an empirical hypothesis, but a definition
19. Language / D. Propositions / 1. Propositions
Sentences only express propositions if they are meaningful; otherwise they are 'statements'
19. Language / D. Propositions / 6. Propositions Critique
Talk of propositions is just shorthand for talking about equivalent sentences
22. Metaethics / C. Ethics Foundations / 1. Nature of Ethics / b. Defining ethics
Some people think there are ethical facts, but of a 'queer' sort
A right attitude is just an attitude one is prepared to stand by
22. Metaethics / C. Ethics Foundations / 1. Nature of Ethics / d. Ethical theory
Moral theories are all meta-ethical, and are neutral as regards actual conduct
Moral judgements cannot be the logical consequence of a moral philosophy
22. Metaethics / C. Ethics Foundations / 2. Source of Ethics / c. Ethical intuitionism
Moral intuition is worthless if there is no criterion to decide between intuitions
I would describe intuitions of good as feelings of approval
22. Metaethics / C. Ethics Foundations / 2. Source of Ethics / h. Expressivism
To say an act is wrong makes no further statement about it, but merely expresses disapproval
Approval of historical or fictional murders gives us leave to imitate them
Moral judgements are not expressions, but are elements in a behaviour pattern
22. Metaethics / C. Ethics Foundations / 2. Source of Ethics / i. Prescriptivism
Moral approval and disapproval concerns classes of actions, rather than particular actions
26. Natural Theory / C. Causation / 3. General Causation / d. Causal necessity
The attribution of necessity to causation is either primitive animism, or confusion with logical necessity
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