Essentialism is the view that things have essences. Versions of that view have a long pedigree, going back into ancient Greek philosophy. It has represented mainstream philosophical (and scientific) orthodoxy until relatively recently. However, modern science has generally taken a more nominalistic view of reality, rejecting or abandoning ‘things’ like essences, that cannot be unambiguously observed in some way.
This book argues that that (modern scientific) approach is mistaken, as essences do in fact have a continuing role to play in philosophy and they can in fact be (sort of) observed in the observation of their instances. In any case, the author states, essences are answering a very different set of questions than a modern (materialistic) science are dealing with. So, it is unsurprising that modern sciences neither needs nor wants to engage with them. The question of essences (and by extension, metaphysics) is, to some extent, a question about whether there is more to reality than what is observable and measurable (by humans). The author thinks there is, and this is an account of what it is, and why it needs to be taken into account.
In the author’s opinion, essences provide better explanations of observable similarities in things. Modern science effectively side-steps the question of why things resemble each other, but the idea that there is an essence provides an attempt to explain precisely that point. There are complexities and issues raised by essences, but whether those issues are enough to warrant abandoning the idea is partially a question about what we think is an appropriate answer to questions about what we observe and why the world behaves as it does.
Part of what makes essentialism a controversial philosophy is that it claims that the ‘essences’ within things are a reality. They are not just ideas. And yet (as argued in this book) they are not platonic forms either, existing out there in their own realm, waiting to be discovered.
Those ideas lead inexorably to the problem of what we are to make of the existence of abstract entities like numbers (such as two or root -1). Do numbers have an essence, and does that essence have a real existence out there somewhere, independently of humans? Asking those kinds of questions is a good way of getting to grips with the core implications of theories like the essentialism argued in the book.
This book takes a broadly Aristotelian approach to those kinds of questions. It insists that abstract entities like numbers are ‘abstracted’ from concrete particulars, so numbers can only exist if there is stuff out there to thus ground the quantification which is numbering, or an eternal mind to carry the abstractions as potentialities for stuff.
Yes. But what does that mean, especially when it comes to abstractions like imaginary numbers? Unfortunately, the book does not press those kinds of questions. Indeed, it becomes worryingly vague at some of the most complex points. The author was surprisingly content to simply stop explanations while telling the reader that he did not have time or space to pursue matters further. For example he tells us that, ‘there is no space to examine this proposal…’ (p.126) and ‘…without having space for the details I contend that…’ (p.129).
One of the issues in philosophy is that the devil is all too often in the detail, so it is really not good enough to keep telling the reader that there is not time to pursue the devils in the details. If it really cannot be fitted into the book, then surely those kinds of issue can be dealt with in an article and referred to from the book. (Or perhaps the book could have had a narrower scope, with greater detail).
Overall, the book contains a lot of detail with a lot of argumentation, so it is a book that will be enjoyed most by professional philosophers. The book does well to take ancient and medieval ideas, and to explain them in terms of modern philosophers and modern terminology. So it is a useful summation and explanation of some important issues in philosophy. But the author sometimes assumes significant knowledge in the reader. For example, he tells us of Kripke and Putnam’s ideas that ‘the basic ideas are too well known to require restating here…’ (p.4). They may be well known to professional philosophers, but that kind of approach makes the book harder to access by readers approaching the issues from different disciplines.