Philosophy: the latest answers to the oldest questions, by Nicholas Fearn

To boldly go through inner space

Philosophers, Marx thought, had spent too much time trying to interpret the world: the point was to change it. But it's not clear that he was making a valid distinction. Philosophers' interpretations do change the world, in countless ways.

If an infertile couple gets IVF treatment on the NHS, or a teenage girl starts refusing to eat dead flesh, or a gay couple enters a civil partnership, their lives have been affected by current philosophical debates - about the status of the foetus, the moral distinctions between people and animals, the nature of equality. So knowing what is going on in modern philosophy is not just an academic matter.

While there is never any shortage of books simplifying the thinkers of the past, popular accounts of what the thinkers of today are getting up to are much rarer. Nicholas Fearn's Philosophy is an ambitious attempt to fill the gap - probably not a genuinely popular book, but well suited to the person who has some interest in philosophy but is too lazy to keep up. Like me.

The book falls into three sections, headed Who Am I?, What Do I Know?, and What Should I Do? The first part deals with questions of the self. Is the mind a kind of computer? Could computers ever think? Fearn deals efficiently with these debates, and manages to interview some of the biggest names in the field: Jerry Fodor, leading exponent of the "computational theory of mind", John Searle, Fodor's leading bugbear, and the charismatic Darwinist thinker, Daniel Dennett.

What Do I Know? deals with the perpetually vexed questions of truth, and whether the mind holds innate ideas. We hear from Noam Chomsky, the American pragmatist Richard Rorty, and Colin McGinn, leader of the "new mysterian" school - philosophical defeatists who hold that the structure of the mind makes us incapable of understanding deeper truths.

In What Should I Do?, Fearn talks to the late Bernard Williams about "moral luck" (is the driver whose momentary inattention kills a child more guilty than the driver whose momentary inattention squashes a tin can?), and to Peter Singer about animal liberation.

Though Fearn is by and large even-handed, his own prejudices emerge. He leans towards Anglophone empiricism (his dismissal of Jacques Derrida verges on the contemptuous). Fearn is attracted to the notion that many of our conceptual confusions stem from using nouns ("self", "consciousness") that don't refer to actual things.

Knowing where your interlocutor stands is useful, and I find Fearn's views sympathetic, but once or twice I worried that he doesn't give people a fair crack of the whip. Is Singer's case for animal liberation really as easily undermined as Fearn seems to think? He also puts too much faith in "thought experiments", like Derek Parfit's famous teleportation stories. Having had his body destroyed in one place and re-created elsewhere, is Captain Kirk still the same person? Fearn should have paid attention to a maxim of Dennett's: sometimes a practical impossibility can tell us more than a conceptual possibility.

A picture emerges of a field with its boundaries in constant flux, as advances in technology change the nature of the questions. That we can now see physical structures in the brain that support mental faculties inevitably alters our notion of mind. So Philosophy will fairly soon be out of date. For the moment, it remains a readable, challenging guide to the frontiers of thinking.