7. Deducing

Detective work is an important tool in philosophy. ‘Deducing’ explains the difference between valid and sound arguments. An argument is valid if its premises are true but is only sound if the conclusion is true. The Greek philosophers identified disjunctive syllogism—the idea that if something is not one thing, it must be another. This relates to another philosophical concept, the ‘law of the excluded middle’. An abduction is a form of logical inference which attempts to find the most likely explanation. Modal logic, an extension of classical logic, is a popular branch of logic for philosophical arguments.

11. Conclusion

Philosophy is a science, interconnected with others and as autonomous as others. The Conclusion looks at the future of philosophy, and whether it will withstand the pressures on it to be something else—pop science, literature, or alternative religion. Humans are naturally curious—we wonder about things and ask questions, whether we are philosophers or not. This curiosity may help philosophy to survive, through an iterative human-led journey of improvement like the trajectory it has taken already. Philosophical methods can be improved, just as other scientific methods can be improved; the only remaining question is how.

5. Doing thought experiments

Reasonable true belief without knowledge is possible, but knowledge is not only justified true belief—so what is it? ‘Doing thought experiments‘ explores how human beings use their imagination and intuition to solve philosophical problems in imaginary scenarios. Thought experiments have played a major role in recent moral philosophy. Sometimes thought experiments are enacted in real life, whereas some can only be imagined. The challenge is to come up with a scenario interesting enough to prove. Through imagining something fully, we know that it is possible, but imagination is not infallible. What if we all gave the same verdict on a thought experiment, but were wrong?

4. Clarifying terms

The detection of ambiguity plays a central systematic role in philosophy. ‘Clarifying terms’ argues that an apparent dispute might mask an agreement and vice versa, depending on the words and concepts employed. If a concept is a dictionary definition, is a conception an encyclopaedia entry? One definition may be more useful than another, but not necessarily truer. Mathematics provides useful models. The view of Platonism is that there are such things as abstract objects that are non-physical, non-mental, and do not exist in space or time. Philosophers know that dictionary definitions are inadequate, but the clarity they seek aims towards questions, not indubitable answers.

3. Disputing

What has combat to do with the pursuit of truth? ‘Disputing’ explores the role of debate in philosophy, in which the question-and-answer session is as important as the lecture. The debate can be constructive as well as combative. There is a danger that quieter voices will be drowned out by bluster. Legal disputes are a useful comparison—two sides are not always equal but are more effective than a single magistrate. From Plato onwards, the spoken or written dialogue was an important philosophical tool, and medieval scholars formalized debate into logic games. Disputes can be challenging but preferable to environments where criticism is discouraged.

2. Starting from common sense

Can we escape our reliance on common sense? ‘Starting from common sense’ examines what common sense is, what it isn’t, and its usefulness as a check on philosophy. Aristotle, Thomas Reid, and G.E. Moore were all advocates of common sense—specifically, the common sense of their own time and place—whereas Bertrand Russell dismissed it as pre-scientific barbarism. There is a concern that common sense may become confused with common belief or used as a disguise for popular prejudice. Our evidence for philosophical experiments depends on common-sense methods of thinking. We have no choice but to start at common sense, but we do not have to end at it.

1. Introduction

The Introduction focuses on the history of philosophy and intersections between philosophy, common sense, natural science, and mathematics, exploring what it means to do philosophy well in practice. How do we confirm that the methods philosophers use are appropriate for answering their questions? How is philosophy related to science? From the ancient Greeks onwards, philosophy included the study of the natural world. Galileo and Newton were scientists, Descartes a mathematician. When natural science and mathematics grew apart and developed their distinct methodologies, why was philosophy not rendered obsolete? What can philosophical methods still do better than scientific and mathematical methods?

10. Model-building

Rather than spending their careers trying to prove universal laws or creating something proven but underwhelming, scientists build manageable models. ‘Model-building’ focuses on how this approach can be applied to philosophy. Model-building is an alternative to philosophy’s historical reliance on counterexamples, which tends towards falsification or artificiality. Returning to linguistics, Rudolf Carnap built a complete system of semantics for an artificial formal language, thus discovering new insights about language itself. Where good models are available, we may get our best results by using several methods as our hypothesis becomes stronger if they are independently pulling in the right direction. The model-building methodology’s potential is only just being realized.

9. Using other fields

‘Using other fields’ looks at the connections between philosophy and other fields of systemic enquiry, from psychology and history to physics, economics, and computer science. Reading history is the closest we get to conducting experiments in politics, creating theories of political philosophy. Social anthropology helps us understand different cultures, beliefs, and arguments. Linguistics matters, as language is the essential medium of philosophy and looking for valid patterns across words helps us to assess philosophical experiments. Connections and messages in computer science, hypotheses in economics and mathematics, and perceptions in the sciences, all combine to inform our understanding of philosophy.

8. Using the history of philosophy

Why is history more central to the study of philosophy than of mathematics or science? ‘Using the history of philosophy’ argues for the importance of history for giving students ideas to build on, whereas mathematics and science tend to focus on new ideas. Alan Turing invented his universal computing machines in response to a philosophical question. History gives us evidence of whether ideas were any good, through accounts of contemporary support or opposition, and how they have fared since. The battle of ideas between religious and scientific world views has been fought within philosophy. Has contemporary philosophy absorbed all the significant insights of earlier work?