I have begun to see that with no concept in mind at all it is impossible to start. Defining "concept" though is loaded. For the sake of simplicity let's call it the "basic idea" behind a painting, coupled with the emotional response to that basic idea. So it's thinking and feeling followed closely by visualising. Because a painting is inherently visual.
Many artists move from a more representational (not necessarily "realist") point of view to a deeply felt abstract one. Pure abstraction has been equated with "Formalism" whereby - so the "experts" tell us it is the colour, line, form, texture, shape of the media on the surface which constitute a painting's value. In other words letting "visualising" lead. (You don't hear many painters say this by the way). It's actually not easy to find on the Internet a list of so called "Formalist" painters so I tried to work it out for myself. Rothko, for example, or the English painter Ben Nicholson started off somewhat representational (the latter with still life images and landscapes) but moved inevitably to what some would say was almost pure abstraction, very, very simple lines, shapes and colour. Picasso, Matisse, stayed more in the representational camp (a cow made out of bicycle handle bars is still quite clearly a cow). The work of Keith Vaughan (another English favourite of mine) shows a clear continuum from the representational to the abstract arrangement of shape on surface. But he could not rid himself like Nicholson and Rothko "appear" to have done of the demonstration of his inherent interest in the human form - and to some extent neither could Barbara Hepworth and her compatriot Henry Moore. But this is not to say Nicholson and Rothko were not demonstrating a facet of the human condition and I think it is dangerous to assume they were not. In a way I think they pushed as far as they could go, the concept of our relationship with the world around us. It sounds vague but I sense that those paintings could not "move" me (and they do) if there was not that underlying sensitivity to what it means to be essentially "human" on the part of their executors. Let's not forget that all Hopper wanted to do towards the end was to paint the slant of light upon a wall, yet he had spent his whole painting life depicting people. Maybe without the people there can have been no wall. Or not one we would have wanted to look at.
We must not forget there are two actors in all this - the painter and the viewer. A painter's deep seated "concept" may lie as much in their subconscious as conscious mind. But the painter's concept is one thing. The response of the viewer is a quite different thing. We might appreciate a Matisse precisely because of the harmony and courage of colour, shape and line and care little for his motivation but Matisse may have seen it quite differently. We don't know and a few give away quotes from the literature do not really prove anything.
The painter's dilemma is always first "what concept do I have at this moment in time?" If the concept is - let me see how far I can push that line; let's see how far I can extend that shape or obliterate that detail - then fine but the line and the shape cannot simply be mechanically formed on the canvas, however "beautiful" they may be. There has to be a history to them. There has to be some emotion or deep knowledge in the making of that line or that shape. For me painting has to be about an emotional response and to some extent that is what I am hoping for when I view the work of other painters. Does that painting move me in whatever whispered, subtle or outrageous way it is possible to be moved? My concept has to serve that end whichever stage of the journey I find myself on.
For the few people who will read this do not be dismayed if you say to yourself "not sure what point she is making" because I am not sure either, just that I know these are conversations that as painters we should be having, not least with ourselves.