02 Truth and Rationality
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02 Truth and Rationality. Philosophy. Part I: Sentences and Propositions. 2. Consider the following two sentences: (1) “snow is white” (2) “snow is white” Are these the same sentence?. 3. Consider the following two sentences: (1) “snow is white” (2) “snow is white”

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02 Truth and Rationality

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02 truth and rationality

02 Truth and Rationality

Philosophy


02 truth and rationality

Part I: Sentences and Propositions

2


02 truth and rationality

Consider the following two sentences:

(1) “snow is white”

(2) “snow is white”

Are these the same sentence?

3


02 truth and rationality

Consider the following two sentences:

(1) “snow is white”

(2) “snow is white”

Are these the same sentence?

Yes and No.

4


02 truth and rationality

Consider the following two sentences:

(1) “snow is white”

(2) “snow is white”

They are different “tokens” of the same sentence “type”.

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02 truth and rationality

Consider the following two sentences:

(1) “snow is white”

(2) “snow is white”

They are different “tokens” of the same sentence “type”. They are two different physical instances of the same one abstract pattern of symbols.

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02 truth and rationality

The distinction between a type and its tokens is a metaphysical distinction between a single abstract thing and its many concrete and particular instances.

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02 truth and rationality

The distinction between a type and its tokens is a metaphysical distinction between a single abstract thing and its many concrete and particular instances.

Tokens are individual physical things that exist at a time and place and are composed of thinks like ink, chalk, vibrations in sound, and so on.

.

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02 truth and rationality

The distinction between a type and its tokens is a metaphysical distinction between a single abstract thing and its many concrete and particular instances.

Tokens are individual physical things that exist at a time and place and are composed of thinks like ink, chalk, vibrations in sound, and so on.

Types aren't composed of anything. They are not physical nor do they exist in time. They are abstract.

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02 truth and rationality

EXAMPLE: The number of words in the Gertrude Stein line from her poem Sacred Emily:

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02 truth and rationality

EXAMPLE: The number of words in the Gertrude Stein line from her poem Sacred Emily:

Rose is a rose is a rose is a rose.

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02 truth and rationality

EXAMPLE: The number of words in the Gertrude Stein line from her poem Sacred Emily:

Rose is a rose is a rose is a rose.

In one sense of ‘word’ we may count three different words; in another sense we may count ten different words.

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02 truth and rationality

EXAMPLE: The number of words in the Gertrude Stein line from her poem Sacred Emily:

Rose is a rose is a rose is a rose.

In one sense of ‘word’ we may count three different words; in another sense we may count ten different words.

Three different types, ten different tokens.

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02 truth and rationality

Consider the following two sentences:

(1) “snow is white”

(2) “neigh est blanc”

Are these the same sentence?

14


02 truth and rationality

Consider the following two sentences:

(1) “snow is white”

(2) “neigh est blanc”

They are different sentence tokens and types. However, they do have something in common.

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02 truth and rationality

Consider the following two sentences:

(1) “snow is white”

(2) “neigh est blanc”

They are different sentence tokens and types. However, they do have something in common. They share the same “meaning”.

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02 truth and rationality

Consider the following two sentences:

(1) “snow is white”

(2) “neigh est blanc”

They are different sentence tokens and types. However, they do have something in common. They share the same “meaning”

(a.k.a. They express the same “proposition”).

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02 truth and rationality

The distinction between a sentence and its meaning is a distinction between the proposition someone is expressing and the mere physical sentence token they are using to express it.

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02 truth and rationality

The distinction between a sentence and its meaning is a distinction between the proposition someone is expressing and the mere physical sentence token they are using to express it.

Sentences are individual physical things (sentence tokens) that are instances of a certain language's pattern (sentence types).

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02 truth and rationality

The distinction between a sentence and its meaning is a distinction between the proposition someone is expressing and the mere physical sentence token they are using to express it.

Sentences are individual physical things (sentence tokens) that are instances of a certain language's pattern (sentence types).

Propositions aren't composed of anything nor are they in any language. They are not physical nor do they exist in time. They are abstract. Propositions don't have tokens, but they can be “expressed” by sentence tokens.

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02 truth and rationality

Consider the following sentences:

(1) “Jane is taller than Ann.”

(2) “Jane is taller than Ann.”

(3) “Ann is shorter than Jane.”

(4) “Jane est plus grand que Ann.”

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02 truth and rationality

Consider the following sentences:

(1) “Jane is taller than Ann.”

(2) “Jane is taller than Ann.”

(3) “Ann is shorter than Jane.”

(4) “Jane est plus grand que Ann.”

How many sentence tokens?

How many sentence types?

How many propositions are expressed?

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02 truth and rationality

Consider the following sentences:

(1) “Jane is taller than Ann.”

(2) “Jane is taller than Ann.”

(3) “Ann is shorter than Jane.”

(4) “Jane est plus grand que Ann.”

How many sentence tokens? Four.

How many sentence types? Three.

How many propositions are expressed? One.

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02 truth and rationality

Consider the following sentences:

(1) “I am hungry.”

(2) “I am hungry.”

(3) “He is hungry.”

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02 truth and rationality

Consider the following sentences:

(1) “I am hungry.”

(2) “I am hungry.”

(3) “He is hungry.”

How many sentence tokens? Three.

How many sentence types? Two.

How many propositions are expressed? ???

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02 truth and rationality

Sentence types do not literally express propositions (i.e. sentence types do not have meanings).

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02 truth and rationality

Sentence types do not literally express propositions (i.e. sentence types do not have meanings).

Only sentence tokens express propositions (i.e. have meanings).

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02 truth and rationality

Consider the following sentences:

(1) “I am hungry.”

(2) “I am hungry.”

(3) “He is hungry.”

How many sentence tokens? Three.

How many sentence types? Two.

How many propositions are expressed? ???

28


02 truth and rationality

Consider the following sentences:

(1) “I am hungry.”

(2) “I am hungry.”

(3) “He is hungry.”

How many sentence tokens? Three.

How many sentence types? Two.

How many propositions are expressed? ???

To know the propositions expressed we need the “context” of each of the three sentence tokens.

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02 truth and rationality

Consider the following sentences:

(1) “I am hungry.”

(2) “I am hungry.”

(3) “He is hungry.”

30


02 truth and rationality

Consider the following sentences:

(1) “I am hungry.”

(2) “I am hungry.”

(3) “He is hungry.”

It is only from the context in which each of the three sentence tokens occurred that we can determine who is being said to be hungry and when it is being claimed that they are hungry.

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02 truth and rationality

Consider the following sentences:

(1) “I am hungry.”

(2) “I am hungry.”

(3) “He is hungry.”

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02 truth and rationality

Consider the following sentences:

(1) “I am hungry.”

(2) “I am hungry.”

(3) “He is hungry.”

Can you imagine a context for these three sentence tokens such that they all express the same proposition? What about a context where they all express different propositions?

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02 truth and rationality

What feature of the context in which the following sentences are said could help you determine what proposition they express?

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02 truth and rationality

What feature of the context in which the following sentences are said could help you determine what proposition they express?

(a)“I am sleepy.”

(b) “You will not be here tomorrow.”

(c) “It is sunny today.”

(d) “We will not tolerate any more of your abuse.”

(e) “Tiffany will be here by noon.”

(d) “No.”

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02 truth and rationality

Consider the following sentences:

(1) “Jane is taller than Ann.”

(2) “Jane is taller than Ann.”

(3) “Ann is shorter than Jane.”

(4) “Jane est plus grand que Ann.”

How many sentence tokens?

How many sentence types?

How many propositions are expressed?

36


02 truth and rationality

Consider the following sentences:

(1) “Jane is taller than Ann.”

(2) “Jane is taller than Ann.”

(3) “Ann is shorter than Jane.”

(4) “Jane est plus grand que Ann.”

How many sentence tokens? Four.

How many sentence types? Three.

How many propositions are expressed? ???

37


02 truth and rationality

Terminology

- Type / Token

-Sentence

-Proposition

-Meaning

-Context

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02 truth and rationality

39


02 truth and rationality

Part I: Sentences and Propositions

Part II: Propositional Attitudes

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02 truth and rationality

Sentence tokens express propositions, but sentence tokens aren't the only thing that involve propositions (a.k.a. meanings).

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02 truth and rationality

Sentence tokens express propositions, but sentence tokens aren't the only thing that involve propositions (a.k.a. meanings).

We can also hope that a proposition is true, wish that a proposition were true, believe a proposition is true, wonder if a proposition is true, imagine a proposition is true, etc.

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02 truth and rationality

Belief, wondering, imagining, hoping, wishing, etc. are all examples of “mental states” that are called “propositional attitudes”. That is, they are mental states about a proposition.

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02 truth and rationality

Belief, wondering, imagining, hoping, wishing, etc. are all examples of “mental states” that are called “propositional attitudes”. That is, they are mental states about a proposition.

By contrast feeling pain, seeing red, hearing a high pitched sound, etc. are all mental states that aren't about propositions. They are not propositional attitudes.

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02 truth and rationality

EXAMPLE:

Experiencing the feeling of pain after being stabbed and wishing that I hadn't been stabbed.

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02 truth and rationality

EXAMPLE:

Experiencing the feeling of pain after being stabbed and wishing that I hadn't been stabbed.

Both are mental states. But the feeling of pain from the stabbing isn't about a proposition while the wish is about the proposition “I've been stabbed.”

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02 truth and rationality

EXAMPLE:

Experiencing the feeling of pain after being stabbed and wishing that I hadn't been stabbed.

Both are mental states. But the feeling of pain from the stabbing isn't about a proposition while the wish is about the proposition “I've been stabbed.”

Pain is just a feeling/experience, but a wish is always a wish about a proposition. When I wish, I always that a proposition. But I don't pain that a proposition.

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02 truth and rationality

At this point we know that a belief is (1) a mental state, and (2) a propositional attitude.

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02 truth and rationality

At this point we know that a belief is (1) a mental state, and (2) a propositional attitude.

So, like wishing and experiencing pain, belief is a mental state. Unlike pain but similar to a wish, a belief is a propositional attitude. That is, like a wish, a belief is about a proposition.

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02 truth and rationality

So what is unique about the mental state/propositional attitude of belief? How does belief differ from other mental states/propositional attitudes like wishing, imagining, wondering, hoping, and so on?

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02 truth and rationality

When someone thinks a proposition is true, that means they believe that proposition. A belief is the mental state of thinking that a proposition is true.

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02 truth and rationality

When someone thinks a proposition is true, that means they believe that proposition. A belief is the mental state of thinking that a proposition is true.

And thinking a proposition is true ranges from just barely thinking a proposition is more likely true than false (51% likelihood) up to being absolutely certain that it is (100% likelihood).

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02 truth and rationality

Furthermore, since belief covers the range from thinking a proposition is just barely more likely to be true than false all the way up to being absolutely convinced that it is true rather than false (51-100% likelihood), we should note that belief really comes in degrees.

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02 truth and rationality

Furthermore, since belief covers the range from thinking a proposition is just barely more likely to be true than false all the way up to being absolutely convinced that it is true rather than false (51-100% likelihood), we should note that belief really comes in degrees.

We don't just believe or don't believe, we believe to a certain degree.

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02 truth and rationality

Lastly, we should note that once I consider a proposition I must then either belief it (think that it has a 51-100% likelihood of being true), disbelief it (think that it has a 0-49% likelihood of being true; that it is likely false), or suspend belief about it (think that it is 50-50% whether it is true or false).

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02 truth and rationality

Lastly, we should note that once I consider a proposition I must then either belief it (think that it has a 51-100% likelihood of being true), disbelief it (think that it has a 0-49% likelihood of being true; that it is likely false), or suspend belief about it (think that it is 50-50% whether it is true or false).

There are many propositions I don't believe, disbelieve, or even suspend judgment about. But those are only the propositions I have never considered.

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02 truth and rationality

Terminology

- Mental State

-Propositional Attitude

-Belief

57


02 truth and rationality

Part I: Sentences and Propositions

Part II: Propositional Attitudes

Part III: Truth

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02 truth and rationality

A belief is the mental state of thinking that a proposition is true.

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02 truth and rationality

A belief is the mental state of thinking that a proposition is true.

But thinking a proposition is true is one thing, that proposition being true is another.

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02 truth and rationality

A proposition is true when it “corresponds to” or “matches” the way the world is, otherwise the proposition is false.

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02 truth and rationality

A proposition is true when it “corresponds to” or “matches” the way the world is, otherwise the proposition is false.

Only propositions (a.k.a. meanings) are truth-bearers. That is, only propositions can be true or false. But we might informally call a belief a true belief if the proposition someone *thinks* is true also happens to be a true proposition.

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02 truth and rationality

A belief is the mental state of thinking that a proposition is true.

A true belief is the mental state of thinking that a proposition is true and that proposition matches the way the world is.

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02 truth and rationality

Suppose I tell you that I believe that “The Earth is spherical” but then say “But I have no idea if my belief is true.” Am I correct in saying this or am I confused?

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02 truth and rationality

Suppose I tell you that I believe that “The Earth is spherical” but then say “But I have no idea if my belief is true.” Am I correct in saying this or am I confused?

Well, whether my belief is true or not depends upon the shape of the Earth, and the Earth could be shaped differently than I believe or have evidence for.

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02 truth and rationality

Suppose I tell you that I believe that “The Earth is spherical” but then say “But I have no idea if my belief is true.” Am I correct in saying this or am I confused?

Well, whether my belief is true or not depends upon the shape of the Earth, and the Earth could be shaped differently than I believe or have evidence for.

But then again, if I believe a proposition, then I think that proposition is true. Therefore, I must also think that any belief in that proposition is a belief in a true proposition (“true belief”).

So, what's the answer;

Am I confused or not?

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02 truth and rationality

Suppose I tell you that I believe that “The Earth is spherical” but then say “But I have no idea if my belief is true.” Am I correct in saying this or am I confused?

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02 truth and rationality

Suppose I tell you that I believe that “The Earth is spherical” but then say “But I have no idea if my belief is true.” Am I correct in saying this or am I confused?

I must be confused. If I believe something, then of course I can't have “no idea” whether my belief is a true one.

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02 truth and rationality

Suppose I tell you that I believe that “The Earth is spherical” but then say “But I have no idea if my belief is true.” Am I correct in saying this or am I confused?

I must be confused. If I believe something, then of course I can't have “no idea” whether my belief is a true one.

I must believe that my original belief is true to the same degree as my original belief. If I believe very strongly that “The Earth is flat” then I also believe very strongly—and for the same reasons—that “A belief that the Earth is flat is a true belief.”

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02 truth and rationality

Suppose I tell you that I believe that “The Earth is spherical” but then say “But I have no idea if my belief is true.” Am I correct in saying this or am I confused?

I must be confused. If I believe something, then of course I can't have “no idea” whether my belief is a true one.

I must believe that my original belief is true to the same degree as my original belief. If I believe very strongly that “The Earth is flat” then I also believe very strongly—and for the same reasons—that “A belief that the Earth is flat is a true belief.” I don't believe 100% that the Earth is flat and so I can admit as an unlikely possibility that my belief could still be false, but that is very different than having “no idea” whether my belief is a true one.

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02 truth and rationality

A point worth noting about how beliefs work:

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02 truth and rationality

A point worth noting about how beliefs work:

If you believe that proposition P is true (think that P has a X% likelihood of being true, where X>50%), then you must also believe that any belief in proposition P is true (think that a belief in P has a X% likelihood of being true).

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02 truth and rationality

Why is this important?

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02 truth and rationality

Why is this important?

Because the fact that the truth of my beliefs isn't up to me and instead depends upon how the world is often leads people to be mistakenly timid in asserting, defending, or thinking that their own beliefs are true.

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02 truth and rationality

Why is this important?

Because the fact that the truth of my beliefs isn't up to me and instead depends upon how the world is often leads people to be mistakenly timid in asserting, defending, or thinking that their own beliefs are true.

Yes, we should realize that whether our beliefs are true or not depends upon how the world is and not upon what we think or have evidence for. But all this entails is that we should limit the degree of confidence with which we think anything is true; in considering whether our beliefs are true, we should still “believe our beliefs” to the same limited degree that we have those beliefs in the first place.

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02 truth and rationality

Terminology

- True / Truth

-False / Falsity

-Truth-bearer

-True Belief

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02 truth and rationality

Part I: Sentences and Propositions

Part II: Propositional Attitudes

Part III: Truth

Part IV: Rationality

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02 truth and rationality

A belief is the mental state of thinking that a proposition is true.

A true belief is the mental state of thinking that a proposition is true and that proposition matches the way the world is.

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02 truth and rationality

A belief is the mental state of thinking that a proposition is true.

A true belief is the mental state of thinking that a proposition is true and that proposition matches the way the world is.

Question: What beliefs should we have?

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02 truth and rationality

Question: What beliefs should we have?

The answer seems obvious: “true beliefs”.

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02 truth and rationality

Question: What beliefs should we have?

The answer seems obvious: “true beliefs”.

But whenever we think about what we “should” do in our actions or in our beliefs, we have to consider whether we can guide our actions or beliefs to live up to what we should do.

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02 truth and rationality

Question: What beliefs should we have?

The answer seems obvious: “true beliefs”.

But whenever we think about what we “should” do in our actions or in our beliefs, we have to consider whether we can guide our actions or beliefs to live up to what we should do.

Can I follow the rule: Only adopt true beliefs?

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02 truth and rationality

Question: What beliefs should we have?

The answer seems obvious: “true beliefs”.

But whenever we think about what we “should” do in our actions or in our beliefs, we have to consider whether we can guide our actions or beliefs to live up to what we should do.

Can I follow the rule: Only adopt true beliefs? No.

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02 truth and rationality

Question: What beliefs should we have?

What I can do, is ensure that I only adopt beliefs whose truth is supported by my evidence.

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02 truth and rationality

Question: What beliefs should we have?

What I can do, is ensure that I only adopt beliefs whose truth is supported by my evidence.

Whether my beliefs are true beliefs depends on how the world is and that isn't something I can check. But what I can do is make sure that the propositions I believe are ones I have evidence for their truth.

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02 truth and rationality

Question: What beliefs should we have?

I should believe propositions my evidence shows are probably true (51-100%), I should disbelieve those propositions my evidence shows are probably false (0-49%), and I should suspend judgment towards those propositions my evidence leaves it completely in the air whether they are true or false (50-50%).

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02 truth and rationality

A belief is the mental state of thinking that a proposition is true.

A true belief is the mental state of thinking that a proposition is true and that proposition matches the way the world is.

A rational belief is the mental state of thinking that a proposition is true and the likely truth of that proposition is supported by the person's evidence.

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02 truth and rationality

Truth is a relationship between a proposition and the world.

Rationality is a relationship between a proposition and a particular person's evidence.

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02 truth and rationality

Truth is a relationship between a proposition and the world.

Rationality is a relationship between a proposition and a particular person's evidence.

These are different relationships and while a proposition can have both, a proposition can also have one without the other.

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02 truth and rationality

Fallibilism and Improbable Truths

Let’s say you believe the procedure will work for mom.

Belief is rational because supported by evidence.

But, let’s imagine the worst: the procedure killed mom.

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02 truth and rationality

Fallibilism and Improbable Truths

Let’s say you believe the procedure will work for mom.

Belief is rational because supported by evidence.

But, let’s imagine the worst: the procedure killed mom.

Fallibilism: Rational beliefs can be false.

Also sad, but true: Irrational beliefs can be true.

Example: Given the odds, it is irrational for any contestant on American Idol to believe she will win. However, one irrational person will turn out to be right.

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02 truth and rationality

Rationality vs. Truth

Why try to have rational belief if rational belief can be false?

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02 truth and rationality

Rationality vs. Truth

Why try to have rational belief if rational belief can be false?

Rational beliefs are based on evidence that give us reason to think a proposition is true.

But evidence can’t guarantee the truth of a proposition.

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02 truth and rationality

Terminology

- Rational Belief

-Evidence

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02 truth and rationality

Part I: Sentences and Propositions

Part II: Propositional Attitudes

Part III: Truth

Part IV: Rationality

Part V: Relativism

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02 truth and rationality

Is truth the same for everyone or does it change from person to person, from time to time, from place to place, and so on?

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02 truth and rationality

Is truth the same for everyone or does it change from person to person, from time to time, from place to place, and so on?

Is a proposition true. Period. Full stop.

Or are propositions only true for a particular person, time, place, and so on?

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02 truth and rationality

We often talk about how truth can change relative to a time, place, or person. This is called “relativism about truth”.

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02 truth and rationality

We often talk about how truth can change relative to a time, place, or person. This is called “relativism about truth”.

However, this is a misconception about truth due to a failure to keep clear about the subtle distinctions we have been discussing.

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02 truth and rationality

Some of the confusion stems from overlooking the differences between belief, true belief, and rational belief.

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02 truth and rationality

A belief is the mental state of thinking that a proposition is true.

A true belief is the mental state of thinking that a proposition is true and that proposition matches the way the world is.

A rational belief is the mental state of thinking that a proposition is true and the likely truth of that proposition is supported by the person's evidence.

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02 truth and rationality

But some of the confusion stems from overlooking the difference between a sentence and a proposition.

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02 truth and rationality

A proposition is true just in case it describes things as they actually are. A proposition is false just in case it fails to describe things as they actually are. (A true proposition corresponds to the facts. A false proposition does not.)

Relativism is the claim that truth is relative to an individual person’s perspective or experiences, a particular time, or a particular place.

-Confusion between sentences and propositions.

-Confusion between belief and true belief.

-Confusion between true belief and rational belief.

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02 truth and rationality

Terminology

- Relativism about truth

- “True for...”

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02 truth and rationality

Part I: Sentences and Propositions

Part II: Propositional Attitudes

Part III: Truth

Part IV: Rationality

Part V: Relativism

Questions?

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