My Web of Opinions, FWIW:
Ontology and Epistemology: Philosophy is very much a matter of opinion. But that doesn't mean that one philosophical position is as good as another. Some are better than others - but not because they are better supported by reasons. "Support" has nothing whatever to do with the goodness of a philosophical position. Instead, positions should be judged by their merits as a vantage point. Philosophers shouldn't seek positions based on truth, they should seek positions based on fruitfulness.
Language and Logic: Bertrand Russell and W.V.O. Quine have much to answer for. Michael Dummett, Saul Kripke, and David Lewis have repaired some of the damage. Eliezer's naive realism and over-enthusiasm for reductionism set my teeth on edge. We need a more pluralist account of theories, models, and science. Type theory and constructivism are the wave of the future in foundational mathematics.
Ethics: Ethics answers the question "What actions deserve approval or disapproval?" (Not the question "What ought I to do?") The question is answered by Nash(1953) in the two-person case. Actions that do not at least conform to the (unique, correct) bargain deserve disapproval and punishment. Notice that the question presumes rational agents with perfect information - that is why what you ought (ethically) to do may sometimes differ from what you ought (practically) to do. Future utilities should be discounted at a rate of at least 1% per year (50% per lifetime).
Rationality and decision theory. I suspect that TDT/UDT are going in the wrong direction, but perhaps I just don't understand them yet. The most fruitful issues for research here seem to be in modeling agents as coalitions of subagents, creating models in which it can be rational to change one's own utility function, biology-inspired modeling using Price equations and Hamilton's rule, and the question of coalition formation and structure in multi-agent Nash bargaining. Oh yeah: And rational creation/destruction of one agent by another.
Futurism: The biggest existential risk facing mankind is uFAI. Trying to build a FOOMing AI which has the fixed goal of advancing extrapolated human values seems incredibly dangerous to me. Instead, I think we should try to avoid a singleton and do all we can to prevent the creation of AIs with long-term goals. But at this stage, that is just a guess. There is a 50%+ probability, though, that there is no big AI risk at all, and that super-intelligences will not be all that much more powerful than smart people and organizations.
Note: posting this feels very self-indulgent. Though I do see value in setting it down as a milestone for later comparison.
Perplexed,
I'm curious to know what you mean by saying that philosophy is a matter of opinion. From your paragraph, it appears you would say that even the most highly confirmed and productive theories of physics and chemistry are also matters of "opinion." For me, that's an odd way to use the term "opinion", but unfortunately, I don't own a trademark on the term! :)
Have I understood you correctly?
Every few months, I post a summary of my beliefs to my blog. This has several advantages:
To those who are willing: I invite you to post your own web of beliefs. I offer my own, below, as an example (previously posted here). Because my world is philosophy, I frame my web of beliefs in those terms, but others need not do the same:
My Web of Beliefs (Feb. 2011)
Philosophy
Philosophy is not a matter of opinion. As in science, some positions are much better supported by reasons than others are. I do philosophy as a form of inquiry, continuous with science.
But I don’t have patience for the pace of mainstream philosophy. Philosophical questions need answers, and quickly.
Scientists know how to move on when a problem is solved, but philosophers generally don’t. Scientists don’t still debate the fact of evolution or the germ theory of disease just because alternatives are (1) logically possible, (2) appeal to many people’s intuitions, (3) are “supported” by convoluted metaphysical arguments, or (4) fit our use of language better. But philosophers still argue about Cartesian dualism and theism and contra-causal free will as if these weren’t settled questions.
How many times must the universe beat us over the head with evidence before we will listen? Relinquish your dogmas; be as light as a feather in the winds of evidence.
Epistemology
My epistemology is one part cognitive science, one part probability theory.
We encounter reality and form beliefs about it by way of our brains. So the study of how our brains do that is central to epistemology. (Quine would be pleased.) In apparent ignorance of cognitive science and experimental psychology, most philosophers make heavy use of intuition. Many others have failed to heed the lessons of history about how badly traditional philosophical methods fare compared to scientific methods. I have little patience for this kind of philosophy, and see myself as practicing a kind of ruthlessly reductionistic naturalistic philosophy.
I do not care whether certain beliefs qualify as “knowledge” or as being “rational” according to varying definitions of those terms. Instead, I try to think quantitatively about beliefs. How strongly should I believe P? How should I adjust my probability for P in the face of new evidence X? There is a single, exactly correct answer to each such question, and it is provided by Bayes’ Theorem. We may never know the correct answer, but we can plug estimated numbers into the equation and update our beliefs accordingly. This may seem too subjective, but remember that you are always giving subjective, uncertain probabilities. Whenever you use words like “likely” and “probable”, you are doing math. So stop pretending you aren’t doing math, and do the math correctly, according to the proven theorem of how probable P given X is – even if we are always burdened by uncertainty.1
Language
Though I was recently sympathetic to the Austin / Searle / Grice / Avramides family of approaches to language, I now see that no simple theory of meaning can capture every use (and hypothetical use) of human languages. Besides, categorizing every way in which humans use speech and writing to have an effect on themselves and others is a job for scientists, not armchair philosophers.
However, it is useful to develop an account of language that captures most of our discourse systematically – specifically for use in formal argument and artificial intelligence. To this end, I think something like the Devitt / Sterelny account may be the most useful.
A huge percentage of Anglophone philosophy is still done in service of conceptual analysis, which I see as a mostly misguided attempt to build a Super Dictionary full of definitions for common terms that are (1) self-consistent, (2) fit the facts if they are meant to, and (3) agree with our use of and intuitions about each term. But I don’t think we should protect our naive use of words too much – rather, we should use our words to carve reality at its joints, because that allows us to communicate more effectively. And effective communication is the point of language, no? If your argument doesn’t help us solve problems when you play Taboo with your key terms and replace them with their substantive meaning, then what is the point of the argument if not to build a Super Dictionary?
A Super Dictionary would be nice, but humanity has more urgent and important problems that require a great many philosophical problems to be solved. Conceptual analysis is something of a lost purpose.
Normativity
The only source of normativity I know how to justify is the hypothetical imperative: “If you desire that P, then you ought to do Y in order to realize P.” This reduces (roughly) to the prediction: “If you do Y, you are likely to objectively satisfy your desire that P.”2
For me, then, the normativity of epistemology is: “If you want to have more true beliefs and fewer false beliefs, engage in belief-forming practices X, Y, and Z.”
The normativity of logic is: “If you want to be speaking the same language as everyone else, don’t say things like ‘The ball is all green and all blue at the same time in the same way.’”
Ethics, if there is anything worth calling by that name (not that it matters much; see the language section), must also be a system of hypothetical imperatives of some kind. Alonzo Fyfe and I are explaining our version of this here.
Focus
Recently, the focus of my research efforts has turned to the normative (not technical) problems of how to design the motivational system of a self-improving superintelligent machine. My work on this will eventually be gathered here. A bibliography on the subject is here.