Not too long ago, I had a Twitter exchange with Philosophy Talk’s Joshua Landy about whether Sigmund Freud was a good philosopher. I took the position that Freud was a good philosopher (in fact, an excellent one) while Joshua expressed the opposite view. I left the conversation feeling perplexed. How could we have such wildly different assessments of the same guy? At first, I thought that one of us must be wrong, and started to worry that it was me. Then, reflecting further, it struck me that I’ve never given much thought to the question of what good philosophy is—and that maybe my dispute with Josh grew out of our having different background ideas about how to answer this question.

So, what is good philosophy? Is it just a matter of taste? Or are there guidelines for separating the wheat from the chaff?

One consideration is whether a piece of work is executed with technical proficiency. If a philosophical work is sloppy—for instance, because it relies on fallacious reasoning, out-and-out contradictions, or ignores counterexamples—this certainly might count against its being good philosophy. Technical correctness is an attractive criterion because it’s pretty black-and-white. Determining whether an argument is valid is, at least in principle, a purely objective matter. That’s why such judgments often take pride of place as a sieve through which journal submissions are passed when editors have to make a call about whether to accept or reject an article for publication.

But logic and precision aren’t everything, and there are several problems with leaning too heavily on this criterion. One is that it’s possible (and I dare say quite common) for a philosopher to argue impeccably and yet produce philosophical work that’s utterly vapid, not to mention the fact that overly conscientious efforts to plug every argumentative hole by anticipating every possible objection can bury an interesting thesis under a mudslide of qualifications. Another problem is that even the “great” philosophical works—the ones that are included in the canon—are far being entirely lucid fallacy-free, even though their devoted interpreters may have a penchant for papering over cracks in their arguments. And in some cases, the quest for technical expertise just seems irrelevant. Complaining that Nietzsche’s Thus Spoke Zarathustra is short on clear, explicit, logical argumentation simply misses the point.

So, what other guidelines can we turn to? One is that good philosophy is often transformative. It helps us to see the world in new ways, revealing aspects that were previously invisible. I’ve never heard anyone gush that a work of philosophy changed their life because all of its arguments are deductively valid. Rather, they say that it made a difference to them by shining a light in the darkness, making familiar things seem unfamiliar, or helping them attend to what’s truly important in life.

If transformativeness is a philosophical virtue, then there’s something irreducibly subjective about the goodness of philosophical work, because whether or not a piece of philosophy is transformative depends a lot on the receptivity of its consumers. There’s also an aesthetic element involved in this: the form of philosophical discourse is important as well as its content. Some kinds of writing are more likely to have greater impact on some people than other kinds have, even if they all express exactly the same ideas.

What about originality? Planting a new question on the intellectual landscape surely counts in favor of a work being an example of good philosophy. That’s true even if the originator doesn’t pursue an answer to the question very well (or even if they never try to answer it—think of Socrates). Originality is often tied to productivity. A philosophical work is productive to the extent that it spawns more philosophical work in an ongoing research tradition. Alfred North Whitehead’s famous remark that the European philosophical tradition consists of a series of footnotes to Plato epitomizes this idea. Works included in the philosophical canon are by definition highly productive—giving rise to whole philosophical traditions and counter-traditions, and vast, labyrinthine literatures.

But it’s important to recognize that the productivity of a philosophical work rests as much in the social, intellectual, and political milieu into which it is born as it does on the work’s inherent strengths. Copies of David Hume’s Treatise of Human Nature, which is one of Western philosophy’s biggest hits, didn’t immediately fly off the bookstore shelves. Instead, it “fell dead-born from the press, without reaching such distinction as even to excite a murmur among the zealots,” as Hume put it in an autobiographical sketch. If Simone de Beauvoir’s The Second Sex had been written in 14th century Paris, it would have had a rather different reception than it did in 1949. Whether a seed produces a plant depends in large measure on the soil upon which it falls.

To wrap up, it’s hard to spell out exactly what good philosophy boils down to. There’s a diverse tangle of considerations involved which can flow together or come apart, and no clear metric for weighing them against one another. Deciding what’s good philosophy is a messy, often subjective, and historically contingent business. Perhaps, then, there are many ways that works of philosophy can be good, and the fact that smart, well-informed people can disagree so vehemently about them should be celebrated as reflecting the richness and complexity of our peculiar discipline.