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Philosophy

<OpenstaxParagraph>
	<OpenstaxTerm>Global skepticism</OpenstaxTerm> is a view that questions the possibility of all knowledge. To make their case, global skeptics point to the lack of the possibility of certainty in our beliefs. Because we cannot know that our beliefs are true, we cannot know in general. Usually, global skepticism attempts to undermine the possibility of forming justified beliefs. Global skeptics target all beliefs, or all beliefs about the external world (which amounts to most beliefs). Most beliefs tacitly or explicitly assume the existence of an external world. When I have the experience of seeing a bird in a tree and think, “There is a bird in that tree,” I assume that there is an actually existing physical bird in an actually existing physical tree in an actually existing real world outside of me. <OpenstaxEm>There is</OpenstaxEm> means “there exists.” I believe the bird, tree, and world all exist independently of my thoughts. The global skeptic questions beliefs such as these.
</OpenstaxParagraph>
<OpenstaxH3>The Dream Argument</OpenstaxH3>
<OpenstaxParagraph>
	How many times have you realized that you were dreaming <OpenstaxEm>while</OpenstaxEm> you were dreaming? Most people believe that whatever they are dreaming is real during the dream. Indeed, the fact that people think dreams are real while dreaming is what makes nightmares so terrible. If you knew the content of a nightmare was a dream, then it would not be nearly as scary. Zhuang <OpenstaxTerm>Zhou</OpenstaxTerm> (c. 369–286 BCE) was a Chinese Taoist philosopher who argued that for all we know, we could currently be dreaming while thinking we are awake. Imagine dreaming that you are a butterfly, happily flitting about on flowers. When you wake, how can you determine whether you have just woken from dreaming you are a butterfly or you are a butterfly who has just started dreaming that you are human? Zhuang Zhou explains:
</OpenstaxParagraph>
<OpenstaxBlockquote>
	 
	<OpenstaxParagraph>
		While he is dreaming he does not know it is a dream, and in his dream he may even try to interpret a dream. Only after he wakes does he know it was a dream. And someday there will be a great awakening when we know that this is all a great dream. Yet the stupid believe they are awake, busily and brightly assuming they understand things, calling this man ruler, that one herdsman—how dense! Confucius and you are both dreaming! And when I say you are dreaming, I am dreaming, too. (Zhuangzi 2003, 43)
	</OpenstaxParagraph> 
</OpenstaxBlockquote>
<OpenstaxParagraph>
	Zhaung Zhou puts forward the possibility that all of what we take to be conscious experience is actually a dream. And if we are dreaming, then all our beliefs about the external world are false because those beliefs take for granted that our current experience is real.
</OpenstaxParagraph>
<OpenstaxFigure id="fig-00001" src="https://openstax.org/apps/archive/20240226.174525/resources/a24ea5536c4f8df79c1dcdd4c19a01686a1a67bf" alt="Chinese ink drawing depicting a seated man, who appears to be asleep, with a butterfly hovering above his head." mediaType="image/jpeg" width="800" height="617" />
<OpenstaxFigureText width="800">
	<strong>Figure 7.8</strong> Is this a picture of a man dreaming of a butterfly, or is it a picture of a butterfly dreaming of a man? The Chinese philosopher Zhuang Zhou asks us to consider the possibility that everything we consider waking experience might actually be a dream. (credit: “Zhuangzi-Butterfly-Dream” by Ike no Taiga/Wikipedia, Public Domain)
</OpenstaxFigureText>
<OpenstaxH3>The Evil Demon Argument</OpenstaxH3>
<OpenstaxParagraph>
	Nearly two millennia after Zhuang Zhou, René <OpenstaxTerm>Descartes</OpenstaxTerm> also proposed a dream hypothesis. Descartes argued that because dreams often incorporate experiences we have in real life, it is impossible to distinguish between dreaming and waking life (Descartes 2008). But Descartes eventually concludes that even if he could be dreaming, there are still some beliefs he can know, specifically arithmetic. Even in dreams, 1 + 1 = 2, and a square will always have four sides. And so, Descartes devises an even stronger skeptical hypothesis: what if we are being tricked by an evil demon?
</OpenstaxParagraph>
<OpenstaxParagraph>
	Descartes’s evil demon is powerful. It can make you believe things, and it can trick you by controlling your experience. The evil demon can make you believe you are currently eating a sandwich by directly feeding you the sensory experience of eating a sandwich (the sight, the smells, the taste, the feel). Under this scenario, you cannot tell the difference between actually eating a sandwich and merely believing you are eating one because the evil demon is tricking you. If we cannot reliably tell the difference between experiences caused by reality and experiences caused by an evil demon, then we cannot know anything. We can represent Descartes’s argument as follows:
</OpenstaxParagraph>
<OpenstaxOl>
	<OpenstaxLi>
		If I cannot rule out the possibility that an evil demon is tricking me, then I do not have any knowledge of the external world.
	</OpenstaxLi>
	<OpenstaxLi>
		I cannot rule out the possibility that an evil demon is tricking me.
	</OpenstaxLi>
	<OpenstaxLi>
		Therefore, I do not have knowledge of the external world.
	</OpenstaxLi>
</OpenstaxOl>
<OpenstaxParagraph>
	Why does <OpenstaxTerm>Descartes</OpenstaxTerm> claim we can’t have knowledge if we cannot rule out the evil demon hypothesis? If an evil demon is tricking us, then all our beliefs are wrong. And if we cannot rule out the possibility that we are wrong, then we are not justified. And if we are not justified in our beliefs, then we cannot have knowledge of them.
</OpenstaxParagraph>
<OpenstaxH3>Putnam’s Brain in a Vat</OpenstaxH3>
<OpenstaxParagraph>
	If you don’t like evil demons, then consider a more modern version of a skeptical hypothesis: the “<OpenstaxTerm>brain in a vat</OpenstaxTerm>” conceived of by American philosopher and mathematician Hilary <OpenstaxTerm>Putnam</OpenstaxTerm> (1926–2016). Imagine that while you were asleep last night, a group of scientists kidnapped you and took you to their lab. There, they surgically removed your brain and placed it in a vat of nutrients. The scientists then hooked up your brain to a sophisticated new computer system. They were able to download your memories so as to create new experiences. The result is a seamless experience of consciousness between yesterday and today. When you woke this morning, your life seemed to proceed without disruption. Can you prove that you are not a brain in a vat? No, you cannot. The scenario stipulates that your experience will seem exactly the same whether you are a brain in a vat or not. Other, similar skeptical scenarios are easy to come up with. Consider the possibility that you are caught in a virtual reality world or that you are trapped in the Matrix.
</OpenstaxParagraph>
<OpenstaxFigure id="fig-00002" src="https://openstax.org/apps/archive/20240226.174525/resources/ec7e7880c16d74845a40ac1404f741dd72615c32" alt="Sketch of a brain floating in a liquid-filled beaker, connected to a computer console by several electrodes. A thought bubble rising from the brain reads “I’m walking outside in the sun!!”" mediaType="image/jpeg" width="657" height="700" />
<OpenstaxFigureText width="657">
	<strong>Figure 7.9</strong> The “brain in a vat” scenario asks us to consider the possibility that our experiences are the result of deliberate manipulation of our mental processes. (credit: “Brain in a Vat” by Was a bee/Wikimedia, Public Domain)
</OpenstaxFigureText>
<OpenstaxH3>General Structure of Global Skeptical Arguments</OpenstaxH3>
<OpenstaxParagraph>
	Skeptical hypotheses and the arguments that they inspire all have a similar structure:
</OpenstaxParagraph>
<OpenstaxOl>
	<OpenstaxLi>
		If I cannot rule out the possibility of SH, then I cannot be justified in believing that P.
	</OpenstaxLi>
	<OpenstaxLi>
		I cannot rule out the possibility of SH.
	</OpenstaxLi>
	<OpenstaxLi>
		Therefore, I cannot be justified in believing that P.
	</OpenstaxLi>
</OpenstaxOl>
<OpenstaxParagraph>
	SH is a skeptical hypothesis. P is any proposition about the external world. Premise 1 is the skeptic’s challenge—that you must rule out skeptical hypotheses. Premise 2 relies on limitations within your perspective. The skeptic claims that you can rule out the possibility of whatever skeptical hypothesis is at hand only if you are able to construct an argument that defeats that hypothesis using the evidence you have (and a priori knowledge). As demonstrated, this is difficult to do. The nature of the skeptical hypotheses used for global skepticism limits your evidence to the contents of your thoughts. What you take to be evidence of the external world (that you perceive things that seem to be separate from yourself) is effectively neutralized by the possibility of a skeptical hypothesis.
</OpenstaxParagraph>

7.4.1 Global Skepticism

1 Introduction to Philosophy

1.1 What Is Philosophy?

1.1.1 Historical Origins of Philosophy

1.1.2 How It All Hangs Together

1.2 How Do Philosophers Arrive at Truth?

1.2.1 Sources of Evidence

1.2.2 Logic

1.2.3 Conceptual Analysis

1.2.4 Trade-offs

1.3 Socrates as a Paradigmatic Historical Philosopher

1.3.1 “The Life Which Is Unexamined Is Not Worth Living”

1.3.2 Human Wisdom Is Worth Little or Nothing

1.3.3 The Importance of Doing No Harm

1.4 An Overview of Contemporary Philosophy

1.4.1 What Can You Do with a Philosophy Major?

1.4.2 An Overview of Your Philosophy Textbook

2 Critical Thinking, Research, Reading, and Writing

2.1 The Brain Is an Inference Machine

2.1.1 The Brain’s Adaptive Ability to Plan Ahead

2.1.2 The Evolutionary Advantage of Shortcuts

2.2 Overcoming Cognitive Biases and Engaging in Critical Reflection

2.2.1 Critical Reflection and Metacognition

2.2.2 Cognitive Biases

2.3 Developing Good Habits of Mind

2.3.1 Strive for Objectivity

2.3.2 Adopt Epistemic Humility

2.4 Gathering Information, Evaluating Sources, and Understanding Evidence

2.4.1 Start with a Strong Foundation

2.4.2 The SIFT Method (Four Moves for Student Fact Checkers)

2.5 Reading Philosophy

2.5.1 Prepare to Read

2.5.2 Engaging with Philosophical Texts

2.5.3 Pre-reading

2.5.4 First Read

2.5.5 Close Read

2.6 Writing Philosophy Papers

2.6.1 Identify Claims

2.6.2 Collect Evidence and Build Your Case

2.6.3 Organize Your Paper

3 The Early History of Philosophy around the World

3.1 Indigenous Philosophy

3.1.1 Challenges in Researching Indigenous Philosophy

3.1.2 Indigenous African Philosophy

3.1.3 Indigenous North American Philosophical Thought

3.1.4 Mesoamerican Philosophy

3.2 Classical Indian Philosophy

3.2.1 The Vedic Tradition

3.2.2 Classical Indian Darshanas

3.3 Classical Chinese Philosophy

3.3.1 Early Chinese Philosophical Thought prior to Confucius

3.3.2 Confucianism

3.3.3 Daoism

3.3.4 Mohism

4 The Emergence of Classical Philosophy

4.1 Historiography and the History of Philosophy

4.1.1 Presentist Approach

4.1.2 Contextualist Approach

4.1.3 Hermeneutic Approach

4.2 Classical Philosophy

4.2.1 Egyptian Origins of Classical Philosophy

4.2.2 Ancient Greek Philosophy

4.2.3 The Presocratics

4.2.4 Socrates and Plato

4.2.5 Aristotle

4.2.6 Epicureans

4.2.7 Roman Philosophy

4.3 Jewish, Christian, and Islamic Philosophy

4.3.1 Defining Jewish, Christian, and Islamic Philosophy

4.3.2 Early Jewish Philosophy

4.3.3 Early Christian Philosophy

4.3.4 Islamic Philosophy

4.3.5 Late Medieval Philosophy in Christian Europe

4.3.6 Jewish Philosophers in the Christian and Islamic Worlds

4.3.7 The Rise of Reason in the Early Modern Era

5 Logic and Reasoning

5.1 Philosophical Methods for Discovering Truth

5.1.1 Dialectics and Philosophical Argumentation

5.1.2 The Use of Reason to Discover Truth

5.1.3 Testing Hypotheses

5.1.4 Laws of Logic

5.1.5 Normativity in Logic

5.2 Logical Statements

5.2.1 Conditionals

5.2.2 Universal Statements

5.3 Arguments

5.3.1 Getting to the Premises

5.3.2 The Difference between Truth and Logic

5.4 Types of Inferences

5.4.1 Deductive Reasoning

5.4.2 Inductive Inferences

5.4.3 Abductive Reasoning

5.5 Informal Fallacies

5.5.1 Fallacies of Relevance

5.5.2 Fallacies of Weak Induction

5.5.3 Fallacies of Unwarranted Assumption

5.5.4 Fallacies of Diversion

6 Metaphysics

6.1 Substance

6.1.1 Fundamentality: The One and the Many