A minimalist understanding of projectivism sees it as a causal account of our moral experiences which results in moral properties appearing to be in the world. Blackburn pictures this nicely in Chapter 6 of ‘Spreading the Word’ where he describes genuine observed properties impinging on a persons existing habits, emotions, sentiments and attitudes causing that person to ‘see’ moral properties as existing in the world. Of course we do not literally see moral properties in the same way that we see colours but we in projecting our attitudes onto the world the world seems a certain way to us i,e, as containing moral properties. Projectivists commonly cite the following passage from David Hume as their inspiration:
Thus the distinct boundaries and offices of reason and of taste are easily ascertained. The former conveys the knowledge of truth and falsehood: the latter gives the sentiment of beauty and deformity, vice and virtue. The one discovers objects as they really stand in nature, without addition or diminution: the other has a productive faculty, and gilding or staining all natural objects with the colours, borrowed from internal sentiment, raises in a manner a new creation.
David Hume, Enquiries Concerning the Human Understanding and Concerning the Principles of Morals by David Hume, ed. L. A. Selby-Bigge, M.A. 2nd ed. (Oxford: Clarendon Press, 1902). Chapter: APPENDIX I. concerning moral sentiment.
Hume’s talk of ‘gilding and staining’ has been interpreted to be referring to talk about projecting our attitudes and feelings onto the world as opposed to discovering already existing features in the world. In matters of taste we can easily imagine being at a party with dishes from many nationalities and commenting on the various food dishes that ‘this tastes delicious’ and that ‘this tastes disgusting’. Such comments may be taken to be a projection of our own habits and cultivated tastes onto the food whereby we treat the food ‘as if’ it had these properties. The term ‘projection’ signifies that the food does not have these properties but it is our constitution that is, at least partly, if not in the main, responsible for how the food tastes.
However a word of caution is in order. Projection is not like projectile vomit. We do not literally see our own projections. Projection is metaphorical talk for our tendency to think about the world as having certain properties or qualities when in fact those properties or qualities do not exist in the world independently of ourselves but are in fact dependent on ourselves. As such it would seem that talk of projection is committed to seeing our way of thinking about the world as being in some kind of error i,e, due to our projecting our inner states onto the world and as a consequence if our language reflects our projections then talk of projection looks like it is going to entail that we are in some kind of error about how we describe the world.
This point is well put by John McDowell in his paper ‘Projection and Truth in Ethics’
In the case of the supposedly absolute or intrinsic property of disgustingness, what projection leads to is error: one takes what one in fact spreads onto the external world to be something that one finds in the world on to which one spreads it, something that is there anyway-that is there independently of human sentient responses to things.
So the purpose of invoking the metaphor of projection is to explain certain apparent features of reality as reflections of our own subjective responses to a world that really contains no such features. The Projectionist in morals holds that our moral thoughts and and behaviour are best explained by our reacting to a reality that contains nothing by the way of values, duties, rights and so forth. By contrast a realist in morals holds that our moral thought and behaviour is explained by our perceiving, cognizing, or intuiting an independent moral reality.
As such projectionism is standardly taken to be at odds with a realist approach to moral matters. However it is compatible with a number of difference meta-ethical views about how best to explain the content of moral judgement i,e, what makes our moral judgements true or false.