If it helps, by "compatibilism" I mean classical compatibilism

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    Could you share a little more about the context? (What are you reading that made this problem interesting or important? What hypotheses have you formed? What has your research uncovered so far?)
    – Joseph Weissman
    Commented Jan 9, 2019 at 15:37
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    If you have a source where these terms "compatibilism" and "semi-compatibilism" are defined that might also help. Welcome to Philosophy! Commented Jan 9, 2019 at 18:35

1 Answer 1


If I take the following definition as canonical, the answer is clear:

This article [...] considers various strategies by which critics of [Frankfurt-type] examples have tried to rescue the Principle of Alternative Possibilities (PAP), or variations of it, and also considers various responses to these critics. It notes that moral responsibility does not require alternative possibilities, but also believes that freedom does imply alternative possibilities. The resulting view is called semicompatibilism.

(Abstract of Fischer, J. (2005-03-03): Frankfurt-Type Examples and Semi-Compatibilism. In Robert Kane (Ed.), The Oxford Handbook of Free Will. Oxford University Press)

In other words: (Classical) compatibilism assumes that freedom is compatible with determinism (i.e. at least in the physical world the impossibility of alternative possibilities). This is mostly, if not always, coupled with the view that moral responsibility is impossible without freedom. In other words: both freedom and moral responsibility are compatible with determinism.

Semi-compatibilism, on the other hand, holds that while freedom is, in fact, incompatible with determinism (in absence of PAP), moral responsibility is not. It argues for there being moral responsibility even in a world without freedom (of will). Hence semi- compatibilism, since it only endorses one half of what classical compatibilism argues for.

  • By freedom do you mean ability to do otherwise? Commented Jan 10, 2019 at 4:18
  • @user161005: Classically, there are two kinds of freedom distinguished: Firstly, freedom of choice, secondly, metaphysical freedom, i.e. the freedom to actually act otherwise. PAP is consistent with both. There are, in fact, weak versions of compatibilism that treat the mentalistic language of choice as allowing for the PAP without any impact on metaphysical/ontological determinism. They commonly talk about supervenience. This is not the same as semi-compatibilism since they assume that you can choose to do otherwise (even if you are unable to enact the choice), which determines morality.
    – Philip Klöcking
    Commented Jan 10, 2019 at 12:56
  • To be more precise, weak versions of compatibilism argue that you can meaningfully talk about freedom of choice. There are intricacies too subtle to discuss here that are intertwined with problems of semantic externalism. Many authors confuse semantic and ontological externalism (i.e. the view that meaningful propositions need to have extensions in the real world which they refer to vs. there really is the thing we indicate in the real world) which leads to confusions especially in the context of morality and freedom.
    – Philip Klöcking
    Commented Jan 10, 2019 at 13:05
  • For example, you could be perfectly fine with ascribing freedom of choice to persons (i.e. argue that freedom has extension in the world and is meaningful to talk about) without endorsing that there actually is metaphysical freedom in the world. This is one guise of weak compatibilism. On the other hand, you could reject all kinds of (strict/mere) externalism and open up for a lot of other possibilities.
    – Philip Klöcking
    Commented Jan 10, 2019 at 13:15

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